Tag Archives: vitamin-d

Vitamin D: One of the Few Supplements Paleo Dieters May RequireOne of the most persuasive aspects of contemporary Paleo Diets is that you will not have to waste your hard earned dollars on supplements (1, 2).  Once you get going on this lifetime program of eating, except for Vitamin D and possibly fish oil, you will achieve all of the DRI’s recommended by governmental agencies from just the food you eat (1, 2).  Previously, I have extensively covered the calcium issue in a number of scientific publications (2-4), so in this blog, I want to re-emphasize the importance of vitamin D supplementation for health and well being.  As we come out of wintertime and into early Spring, the possibility exists that many of us may be vitamin D compromised or even Vitamin D deficient (5-11).

Why is this?  When we eat the foods that mother nature intended, why should we be deficient in any nutritional element?  Vitamin D is actually not a vitamin, but rather is a hormone naturally formed in our skins when we expose ourselves to the ultraviolet radiation of the sun.  In North America and in Europe, we receive scant little sunshine in the dead of winter, and consequently our body stores of this essential hormone become depleted as we go from Fall to Winter to early Spring (5-11).

Table 1 below lists the content of the 40 most concentrated sources of vitamin D in real, non-fortified foods.  Careful examination of this Table makes it clear that, except for salmon or fresh tuna (12), it is difficult or even impossible to achieve recommended vitamin D intakes (600 I.U. or greater per day) (10, 11) with real, non-fortified foods.

Table 1.  The 40 most concentrated sources of Vitamin D in real, non-fortified foods in the western diet.

Food 100 grams food Vit D I.U. kcal Vit D IU/kcal Vit D IU/100 kcal
Cod liver oil 100 10,000 902 11.09 1109
Catfish, Channel, Wild, Dry Heat 100 568 105 5.41 541
Tuna (bluefin), Fresh, wild, baked/broiled 100 920 184 5.00 500
Salmon, Coho (Silver), Wild,  Baked/Broiled 100 676 139 4.86 486
Salmon, Chinook (King), Wild, Baked 100 904 231 3.91 391
Fish eggs (roe), mixed species 100 484 143 3.38 338
Salmon, Sockeye, Wild Cooked Dry Heat 100 526 169 3.11 311
Oysters, Pacific, Steamed 100 320 163 1.96 196
Salmon, Atlantic Wild Baked 100 328 182 1.80 180
Halibut, Atlantic/Paciific, Baked 100 192 140 1.37 137
Salmon, Atlantic Farmed Baked 100 272 206 1.32 132
Mushrooms, Oyster raw 100 36 33 1.09 109
Herring 100 216 203 1.06 106
Tuna, (yellow fin/albacore), baked/broiled 100 140 139 1.01 101
Sardines in oil 100 193 208 0.93 93
Tuna, Canned in water 100 80 128 0.63 63
Mushrooms, Potabella raw 100 12 22 0.55 55
Mushrooms, Shiitake raw 100 18 34 0.53 53
egg yolks 100 187 351 0.53 53
Cod, Atlantic, Cooking dry heat 100 46 105 0.44 44
Beef, Kidney 100 68 159 0.43 43
Mackerel 100 104 262 0.40 40
Pork liver 100 52 134 0.39 39
Mushrooms, white 100 7 22 0.32 32
Beef liver 100 49 175 0.28 28
Cod, Pacific,  Cooking dry heat 100 24 85 0.28 28
Turkey liver 100 72 273 0.26 26
Salmon oil 100 177 902 0.20 20
Beef, Filet Mignon 100 36 211 0.17 17
Chicken liver 100 16 119 0.13 13
Pork loin 100 34 273 0.12 12
Lamb liver 100 16 139 0.12 12
Lamb, rib roast lean 100 24 232 0.10 10
Mushrooms, Enoki raw 100 4 44 0.09 9
Bacon 100 42 541 0.08 8
Catfish, Channel, Farmed, Dry Heat 100 10 144 0.07 7
Mussels 100 11.2 172 0.07 7
Pork kidney 100 8 151 0.05 5


At the top of the list for natural foods is cod liver oil, which at first appears to be a great source of vitamin D.  It is, but unfortunately it also contains high levels of vitamin A which competes with our bodies’ metabolism for vitamin D and may impair vitamin D metabolism (13).   A better choice is fish oil from the body of fish, rather than the liver.  It also contains vitamin D and the healthful long chain omega 3 fatty acids (EPA and DHA) without the higher concentrations of vitamin A which may impair vitamin D metabolism (13).  

But from an evolutionary perspective, fish oil whether derived from cod liver oil or only the body of fish, was known to have been consumed by the Vikings (circa 700s to 1100 AD) but was not commercially manufactured until relatively recent (200 – 300 years) times.

Accordingly, the Paleo Diet paradigm suggests that (as a species) if we consumed vitamin D from food, it must have come from other sources.  Table1 indicates that salmon is a concentrated source of vitamin D, and if we consume roughly ¼ pound of salmon or more per day (12), we may be able to achieve low level vitamin D balance.  But who do you know who eats a quarter pound or more of salmon a day (day in and day out) in the 21st century?

As you move on down the list of foods in Table 1 from salmon, it becomes increasingly obvious that with our modern tastes and diets, few people could achieve vitamin D balance on any normal diets before modern, fortified foods (milk, margarine and processed foods) were introduced in about the 1930’s and 1940’s.  Organ meats won’t do it, eggs won’t do it, shellfish won’t do it and meat won’t do it.  The obvious implications of Table 1 is that food never was or never could have been the primary source of the hormone, vitamin D, which is essential for optimal human health.  Before I leave this topic, let’s examine milk and dairy products.


Are Dairy Foods Good Sources of Vitamin D?

To even suggest that milk is a good source of vitamin D is a total stretch of the facts.  The Institute of Medicine Daily’s recommended intake for vitamin D is 600 IU per day for most people (14).  Although this advice represents a substantial increase from previous estimates, it still falls far short of human experimental evidence showing that at least 2,000 IU per day is required to keep blood levels of vitamin D at the ideal concentration of 30 ng/ml (6, 7, 10).  See Table 2 below.


Table 2.  Vitamin D Classifications in Blood.

Blood levels of vitamin D Category
less than 20 ng/ml Deficiency
21 to 29 ng/ml Insufficiency
greater than 30 ng/ml Sufficiency
60 ng/ml Maximal with sunlight exposure

An eight oz glass of raw milk (280 calories) straight from the cow without fortification gives you a paltry 3.6 IU of vitamin D.  At this rate, you’d have to drink a ridiculous 167 eight oz glasses of milk just to achieve the 600 IU daily recommendation.  Because most of the milk we drink is fortified with vitamin D, then an 8 oz glass typically yields 100 IU of this nutrient.   However, even with fortification, you would have to drink six 8 oz glasses (1,680 calories or ~ 75 % of your daily caloric intake) of milk to meet the daily requirement for vitamin D.  If you wanted to reach the 2,000 IU level as suggested by the world’s best vitamin D researchers, you would have to drink 20 eight oz glasses of fortified milk amounting to 5,600 calories.   No one in their right mind would drink 20 glasses of milk a day, even if they could.  

As you can see from these simple calculations, whether fortified or raw, milk is an abysmal source of vitamin D.   The best way to get your vitamin D is not by drinking milk, but rather by getting a little daily sun exposure as nature intended.


Sunlight Exposure

Lifeguards and other outdoor workers can achieve blood concentrations that top out at about 60 ng/ml.  But you really don’t need values this high. Most experts agree that values higher than 30 ng/ml will significantly reduce your risk for cancer and all of the other diseases associated with low vitamin D status (15-21).   The good news is that daily sunlight exposure in the summertime for short periods 15-30 minutes will rapidly boost your blood levels of vitamin D above 30 ng/ml.  Something that cannot be achieved with diet alone because almost all real foods, except salmon (12), that we commonly eat contain little or no vitamin D (Table 1).  


Vitamin D Supplementation

For most of us, regular sunlight exposure is a luxury that is difficult or impossible to come by on a year round basis.  Obviously, our hunter gatherer ancestors, living at low to moderate latitudes did not have this problem.  Consequently, you will need to supplement your diet with vitamin D3 capsules.  If we look at the official governmental recommendation for vitamin D intake (between 400 and 600 IU), it is woefully inadequate.  This policy represents a complete failure in public health policy.  The most recent human experiments show that blood levels of 30 ng/ml could never be achieved with vitamin intakes between 400 and 600 IU (6, 7, 10, 11). 400 IU does not help improve insufficient blood concentrations of vitamin D one iota. In fact, a recent series of articles and reviews published in Nutrients demonstrated that the 600 IU recommendation was based on a misinterpretation of the data and was an order of magnitude too low. A meta-analysis of existing studies conservatively estimated daily needs of 1885, 2802 and 6235 IU for normal weight, overweight, and obese individuals respectively (22-24).

The majority of men, women and children in the U.S. maintain blood levels of vitamin D which are either deficient or insufficient (6-11).  Hence, one of the best strategies you can take with adopting The Paleo Diet is to supplement daily with vitamin D3 if you are unable to get sunshine on a regular basis. Most vitamin D experts agree that daily supplementation of at least 2,000 IU of vitamin D3 daily is necessary to achieve healthful blood levels of 30 ng/ml or greater.  


[1] Cordain L. The Paleo Answer. John Wiley & Sons, New York, NY, 2012.

[2] Cordain L. The nutritional characteristics of a contemporary diet based upon Paleolithic food groups. J Am Neutraceut Assoc 2002; 5:15-24.

[3] Cordain L, Eaton SB, Sebastian A, Mann N, Lindeberg S, Watkins BA, O’Keefe JH, Brand-Miller J. Origins and evolution of the western diet: Health implications for the 21st century. Am J Clin Nutr 2005;81:341-54.

[4] O’Keefe JH, Bergman N, Carrera-Basto P, Fontes-Villalba M, DiNicolantonio JJ, Cordain L. Nutritional strategies for skeletal and cardiovascular health: hard bones, soft arteries, rather than vice versa.  Open Heart 2016;3: e000325. doi:10.1136/ openhrt-2015-000325 (in press).

[5] Binkley N, Novotny R, Krueger D, Kawahara T, Daida YG, Lensmeyer G, Hollis BW, Drezner MK. Low vitamin D status despite abundant sun exposure. J Clin Endocrinol Metab. 2007 Jun;92(6):2130-5.

[6] Holick MF, Chen TC: Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr. 2008 Apr;87(4):1080S-6S.

[7] Hollis BW. Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D. J Nutr. 2005 Feb;135(2):317-22.

[8] Kumar J, Muntner P, Kaskel FJ, Hailpern SM, Melamed ML. Prevalence and associations of 25-hydroxyvitamin D deficiency in US children: NHANES 2001-2004. Pediatrics. 2009 Sep;124(3):e362-70.

[9] Melamed ML, Kumar J. Low levels of 25-hydroxyvitamin D in the pediatric populations: prevalence and clinical outcomes. Ped Health. 2010 Feb;4(1):89-97.

[10] Vieth R. Why the optimal requirement for vitamin D3 is probably much higher than what is officially recommended for adults. J Steroid Biochem Mol Biol 2004; 89-90:575-9.

[11] Bischoff-Ferrari HA. Optimal serum 25-hydroxyvitamin D levels for multiple health outcomes. Adv Exp Med Biol. 2008;624:55-71

[12] Lu Z, Chen TC, Zhang A, Persons KS, Kohn N, Berkowitz R, Martinello S, Holick MF. An evaluation of the vitamin D3 content in fish: Is the vitamin D content adequate to satisfy the dietary requirement for vitamin D? J Steroid Biochem Mol Biol. 2007 Mar;103(3-5):642-4. Epub 2007 Jan 30.

[13] Cannell JJ, Vieth R, Willett W, Zasloff M, Hathcock JN, White JH, Tanumihardjo SA, Larson-Meyer DE, Bischoff-Ferrari HA, Lamberg-Allardt CJ, Lappe JM, Norman AW, Zittermann A, Whiting SJ, Grant WB, Hollis BW, Giovannucci E.  Cod liver oil, vitamin A toxicity, frequent respiratory infections, and the vitamin D deficiency epidemic. Ann Otol Rhinol Laryngol. 2008 Nov;117(11):864-70.

[14] https://iom.nationalacademies.org/Reports/2010/Dietary-Reference-Intakes-for-Calcium-and-Vitamin-D.aspx

[15] Dobnig H, Pilz S, Scharnagl H, Renner W, Seelhorst U, Wellnitz B, Kinkeldei J, Boehm BO, Weihrauch G, Maerz W. Independent association of low serum 25-hydroxyvitamin d and 1,25-dihydroxyvitamin d levels with all-cause and cardiovascular mortality. Arch Intern Med. 2008 Jun 23;168(12):1340-9.

[16] Field S, Newton-Bishop JA. Melanoma and vitamin D. Mol Oncol. 2011 Feb 3. [Epub ahead of print]

[17] Forouhi NG, Luan J, Cooper A, Boucher BJ, Wareham NJ. Baseline serum 25-hydroxy vitamin D is predictive of future glycaemic status and insulin resistance: The MRC Ely prospective study 1990-2000. Diabetes. 2008 Oct;57(10):2619-25.

[18] Holick MF. Vitamin D and sunlight: strategies for cancer prevention and other health benefits. Clin J Am Soc Nephrol 2008;3:1548-54.

[19] Holick MF. Optimal vitamin d status for the prevention and treatment of osteoporosis. Drugs Aging. 2007; 24(12):1017-29.

[20] Plum LA, DeLuca HF. Vitamin D, disease and therapeutic opportunities. Nat Rev Drug Discov. 2010 Dec;9(12):941-55

[21] Sharief S, Jariwala S, Kumar J, Muntner P, Melamed ML. Vitamin D levels and food and environmental allergies in the United States: Results from the National Health and Nutrition Examination Survey 2005-2006. J Allergy Clin Immunol. 2011 Feb 15.

[22] Heaney, R., et al., Letter to Veugelers, P.J. and Ekwaru, J.P., A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients 2014, 6, 4472-4475; doi:10.3390/nu6104472. Nutrients, 2015. 7(3): p. 1688-1690.

[23] Veugelers, P.J. and J.P. Ekwaru, A Statistical Error in the Estimation of the Recommended Dietary Allowance for Vitamin D. Nutrients, 2014. 6(10): p. 4472-4475.

[24] Veugelers, P.J., T.M. Pham, and J.P. Ekwaru, Optimal Vitamin D Supplementation Doses that Minimize the Risk for Both Low and High Serum 25-Hydroxyvitamin D Concentrations in the General Population. Nutrients, 2015. 7(12): p. 10189-10208.

Vitamin D Omega 3 Supplements | The Paleo Diet

Choosing a Paleo diet and eating more in tune with how we’ve evolved provides the body with a robust amount of essential protein, healthy fats, gluten-free carbohydrates and nutrient dense veggies. An ancestral approach to eating also provides your body with key nutrients, vitamins and minerals the way nature intended. Does this mean that supplementation is unnecessary if you’re following a Paleo lifestyle? It’s a complicated question.

Most articles and blogs about supplements inevitably discuss the benefits or drawbacks of multi-vitamins. Research shows that if you eat a diet centered around the most nutrient dense foods – quality meats, veggies and fats – you’ll likely already be achieving a therapeutic dose for most vitamins and minerals. When intake is at a supra-physiological dose (that can never be found in nature), too many vitamins can actually put you at risk of chronic disease. Does this mean if you’re following a Paleo diet you don’t need any supplements?

Let’s look at the two most common instances where supplementation might still be a good idea, vitamin D and omega-3 fats. In both of these cases, although a Paleo diet is a great place to start, for many people this may not be enough.


Vitamin D is classically known as an essential nutrient for bone health and immunity, however new research shows this fat-soluble vitamin has much more profound impacts on your health and well-being.

How important is vitamin D? Dr. Michael Holick, physician and vitamin D expert sums it up. “Imagine what would happen if a drug company came out with single pill that reduces the risk of cancer, heart attack, stroke, osteoporosis, PMS, depression and various autoimmune conditions? There would be a media frenzy the likes of which has never been seen before! Such a drug exists… it’s the sun.”1, 2, 3

Vitamin D is different than other vitamins because it’s created under your skin when ultraviolet light from the sun interacts with a specific enzyme to form cholecalciferol or vitamin D3. However, exposure to daily sunlight is no longer the norm as we are cooped up in cubicles all day and the deeply ingrained ancestral benefits of light exposure are overlooked.

It’s estimated that up to 70% of the American population is deficient in vitamin D (defined as blood levels below 20ng/mL or 50 nmol/L), or suffering from vitamin D insufficiency, a level above a diagnosed deficiency but still not sufficient for good health (measured as 20-32 ng/mL or 50-80nmol/L). 4

If you live in a northern climate with a true winter season, or north of the 49th parallel, it’s very difficult to achieve the required blood levels of vitamin D from food alone. While cold-water fatty fish, eggs and mushrooms are good foods sources of vitamin D, in the dead of winter they’re likely not enough. Adding a supplement can be highly beneficial.

The standard medical recommendation for vitamin D drops is 1,000-2,000 IU per day, however in the darkest winter months you may need a higher dose. Remember, always get your blood levels tested and work with a doctor if you’re thinking of supplementing with more than the recommended dose. The normal range is typically between 32-50ng/mL (80-125nmol/L) and for athletes new research suggests achieving levels greater than 40ng/mL (100nmol/L) to support superior performance and recovery.5 Be sure to take your vitamin D supplement with a meal that includes fat for optimal absorption.


Extra long-chain fats eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the omega-3 ‘all-stars’ when it comes to supporting overall health and combating chronic disease. While most people know the benefits of omega-3 fats for cardiovascular health, many don’t realize they also help reduce the risk of diabetes and depression, protect against mental stress, and even support athletic performance by improving muscle protein synthesis and controlling excessive inflammation.

How important are omega-3 fats? In 2013, the Cardiovascular Healthy Study found that people with the highest omega-3 (e.g. EPA and DHA) levels in their blood had the lowest overall mortality rates.6 In short, the more omega-3 fats you consume, the less chance you have of dying from absolutely any cause. The good news is they are found in abundance in a Paleo diet (e.g. grass-fed meats, wild ocean fish, farm fresh eggs). However, modern day living and long, busy days might mean you’ll benefit from extra support.

If you’re prone to low mood or depression, or cope with regularly high stress levels fish oils could well be an important key to improving your brain health. A study in the Journal of Clinical Psychiatry found people experiencing depression had consistently lower levels of essential fatty acids in their blood. When subjects supplemented with fish oils they had significant improvements in their Hamilton Rating Scale, a recognized evaluation system for depression.7 The British Journal of Nutrition also discovered that supplementing with fish oils helps reduce the adrenal over-activation associated with high levels of mental stress.8

Rates of diabetes and pre-diabetes have never been higher, and constantly being on the go is just one factor that can lead to snacking on convenience foods that are high in processed carbs and sugars. A recent study of fish oil supplementation effects on blood sugar and insulin levels over a 3-week period found significant improvements in insulin function in those with elevated levels.9

Of course, it’s not enough just to increase your omega-3 intake. It’s far too easy to obtain excessive amounts of omega-6 type fats in today’s world, whether from processed foods, restaurant eating, or convenience snacks. The beauty of adopting a Paleo diet is that it often naturally restores this common imbalance. However, the impacts of modern living may still leave you short.

Unless you’re eating 1-2 pieces of cold, deep-water fatty fish daily, it’s best to add an omega-3 supplement rich in EPA/DHA. Fish oil is the richest in EPA and DHA, however krill oil, sea oil, and sea algae are all viable options as well. Aim to supplement with 1,000-1,500mg of combined EPA and DHA daily.

If you’re an athlete and training intensely fish oil supplementation can be a game changer. Supplementation can lead to an amazing 50% increase in the up-regulation of mTOR, the genetic signaling pathway that stimulates lean muscle growth, leading to significant increases in muscle protein synthesis and muscular hypertrophy.10  If you’re serious about your training, adding extra omega-3 fats to your sports nutrition arsenal is important.

A Paleo diet is a great way to cover all your bases on the nutrition front. However, depending on your genetics, where you live, how busy you are, and your lifestyle, diet may not be enough to correct low or insufficient levels of vitamin D and omega-3 fats. Adding these two supplements into your regime, particularly throughout the winter months, may be the fix you need to improve your health, productivity at work and performance in the gym.


  1. Holick M.Vitamin D Deficiency:What A Pain It Is. Mayo Clin Proc 2003 78(12):1457-59
  1. Holick, M. Article Review: Vitamin D Deficiency. NEJM Medical Progress. 2007, 357:266-81.
  1. Holick, M. Shinning A Light On Vitamin D-Cancer Connection IARC Report. Dermato-Endocrinology, 2009 1(1):4-6
  1. Hanley D, Davison, K. Symposium: Vitamin D Insufficiency: A significant risk Factor in Chronic Disease and Potential Disease-Specific Biomarkers of Vitamin D Insufficiency: Vitamin D Insufficiency in North America. J Nutr 2005, 135:332-37.
  1. Koundourakis, N et al. Vitamin D and Exercise Performance in Professional Soccer Players. Plos One. 2014 Jul 3;9(7):e101659.
  1. Mozaffarian D, Lemaitre RN, King IB, et al. Plasma phospholipid long-chain omega-3 fatty acids and total and cause-specific mortality in older adults. A cohort study. Ann Intern Med 2013; 158:515-525.
  1. Su K, Huang S, Chiu C, Shen W. Omega-3 fatty acids in major depressive disorder. A preliminary double-blind, placebo-controlled trial. Eur Neuropsychopharmacol 2003;13(4):267-271.
  1. Delarue J et al. Fish oil attenuates adrenergic overactivity without altering glucose metabolism during an oral glucose load in haemodialysis patients. Br J Nutr. 2008 May;99(5):1041-7.
  1. Delarue J et al. Interaction of fish oil and a glucocorticoid on metabolic responses to an oral glucose load in healthy human subjects. Br J Nutr. 2006 Feb;95(2):267-72.
  1. Smith GI et al. Omega-3 polyunsaturated fatty acids augment the muscle protein anabolic response to hyperinsulinaemia-hyperaminoacidaemia in healthy young and middle-aged men and women. Clin Sci (Lond). 2011 Sep;121(6):267-78.

Vegetarian Diet | The Paleo Diet

Did you miss Vegetarian and Vegan Diets: Nutritional Disasters Part 1 or Part 2?
Read Part 1 HERE
Read Part 2 HERE

Vegetarian Diets: Other Nutritional Shortcomings

You don’t have to look any further than the ADA’s Position Statement28 or the USDA’s recommendations on vegetarian diets142 to discover additional nutrient shortcomings caused by plant based diets. The ADA matter of factly mentions that “…key nutrients for vegetarians include protein, n-3 fatty acids, iron, zinc, iodine, calcium, and vitamins D and B12..28 The USDA notes that “…vegetarians may need to focus on…iron, calcium, zinc, and vitamin B12.142 These subtle admissions of potential nutrient deficiency problems associated with vegetarian diets represent the tip of a nutritional nightmare. Just as was the case with vegetarian diets and vitamin B12 deficiency, there is little credible scientific evidence to show that people eating a lifelong plant based diet (without taking supplements or eating fortified foods) can achieve adequate dietary intakes of omega 3 fatty acids (EPA and DHA), iron, zinc, iodine, calcium, and vitamin D. To this list you can also add vitamin B6 and taurine, an amino acid.

Mineral Deficiencies and Vegetarian Diets

One of the major complications with the assessment of dietary nutrient adequacy in vegetarian diets, or for that matter, any diet has to do with whether or not the vitamins and minerals measured in certain foods actually get absorbed into our bodies. The bioavailability of vitamins and minerals in foods is just as important in how they impact our health as is the simple content of these nutrients in a food. By now you know that phytate is not a good thing because it prevents absorption of essential minerals. Whole grains and legumes are rich sources of phytate. Accordingly, our bodies have great difficulty extracting certain minerals from these foods because they are tightly bound to phytate. Phytate in whole grains impairs calcium absorption and may adversely affect bone health. Further, phytate also binds zinc, thereby interfering with its assimilation and incorporation into our cells. To this list you can add iron and magnesium. Because vegetarian diets are virtually impossible to follow without including lots of whole grains, beans, soy and legumes, they are inherently high in phytate. This is why it is difficult or impossible for vegetarians and vegans to maintain adequate body stores of calcium, zinc and iron.

Zinc Deficiencies in Vegetarian Diets

From the discussion above, you know that zinc is crucial for normal male reproductive function, but it is also required for good health and disease resistance in virtually every cell in our bodies, whether you are a man, woman or child.20, 41 Marginal zinc status impairs our immune system, slows wound healing, adversely affects glucose and insulin metabolism, and damages our body’s built in antioxidant system.16, 55 Without adequate dietary zinc we experience more upper respiratory illnesses that last longer. Zinc lozenges can slow or prevent common cold symptoms, and zinc oxide creams applied topically can speed healing. If you have ever experienced painful cracked heels or nose bleeds that just wouldn’t stop, try rubbing zinc oxide ointments on these wounds – you will be amazed at how rapidly zinc can heal these stubborn sores. How we got into this problem (marginal zinc status or deficiencies) in the first place originates directly from our diets. Anybody eating excessive whole grains and/or legumes and not eating meat, fish or animal products on a regular basis45, 59, 62 puts themselves at risk for all illnesses and health problems associated with borderline or deficient zinc intakes.

Iron Deficiencies in Vegetarian Diets

Your body stores of iron run hand in hand with zinc. The same types of diets that produce zinc deficiencies also create iron deficiencies. High phytate vegetarian diets based upon whole grains, beans, soy and other legumes invariably cause iron deficiencies5, 135 which are the most common nutrient deficit worldwide. In the U.S. 9% of all women between 12 and 49 years are iron deficient, while 4% of 3 to 5 year old children have insufficient stores of this crucial mineral.25 If you are pregnant, low iron status increases your risk of dying during childbirth, and frequently causes low birth weights and preterm deliveries. Even more disturbing is the potential for iron deficiencies to prevent normal mental development in our children and young adults.39, 90, 96 As a parent, I would never wish upon my child or for that matter anyone else’s, a diet causing nutritional deficiencies known to impair brain development and normal mental function. But this is just the case if you eat a vegetarian diet and impose it upon your children. Plant based diets not only increase the risk of impaired cognitive function in your children, but will hamper your own mental functioning. Numerous experimental studies show that inadequate iron stores in adults can slow or impair tasks requiring concentration and mental clarity.73

One of the most important outcomes of diets that cause iron deficiencies is that they make us fatigued and tired. If you are an athlete or have a demanding job requiring physical exertion, low iron stores will invariably reduce your performance. A recent (2009) experiment involving 219 female soldiers during military training showed that iron supplements improved blood iron stores, increased performance for a 2 mile run and enhanced mood.92 Similarly a study by Dr. Hinton and colleagues demonstrated that iron supplements in iron deficient male and female athletes improved endurance performance and efficiency.56 Whether you are an athlete, a laborer or even an office worker, your best nutritional strategy to improve iron stores, add vigor to your life and improve performance is to eliminate whole grains and legumes from your diet by adopting The Paleo Diet.

The burden of proof that vegetarian diets will not produce multiple vitamin and mineral deficiencies lies upon the governmental (USDA) and dietary organizations (ADA) that recommend these diets to us all and tell us that they are safe.28, 142 You might expect that the experimental evidence surrounding vegetarian diet recommendations would be convincing and overpowering. Nothing could be further from the truth, particularly when it comes to iron deficiencies and vegetarian diets.

As always the devil is in the details when it comes to getting correct answers to nutritional questions. Scientists who believe that vegetarian diets don’t adversely affect our iron stores often cite scientific papers showing no difference between blood iron concentrations in vegetarians and meat eaters. What they don’t tell us is how iron measurements were performed in the experiments they quote to support their viewpoint. This information is absolutely essential in knowing if iron deficiencies exist or not. Any study examining blood levels of iron in vegetarians using either measurements of hemoglobin (an iron carrying substance in red blood cells) or hematocrit (the concentration of red blood cells) are unreliable indicators of long term iron status. A much better marker is an iron carrying molecule called ferritin.75 Virtually all epidemiological (population) studies of vegans or ovo/lacto vegetarians show them to be either deficient or borderline iron deficient when blood ferritin levels are measured. Given this nearly unanimous finding from epidemiological studies, you might think that either the USDA or the ADA would become concerned and re-examine their endorsement of vegetarian diets. Unfortunately, we still live with governmental and institutional dietary recommendations that may do considerable harm to our health.

The most convincing type of experiments to reveal whether or not vegetarian diets may cause our iron stores to nosedive are called dietary interventions. Why not put a large group of non-vegetarians on a plant based diet for an extended period and see what happens to their blood iron levels? Wow what a great idea – unfortunately no such study has ever been conducted. The closest we have come to this experiment is a short term study (8 weeks) by Dr. Janet Hunt and co-workers at the Grand Forks Human Nutrition Research Center in North Dakota.63 The results of this experiment were anything but conclusive as the researchers made a fundamental blunder in the design of their experiment – they forgot to include a control group. Without a control group, it is impossible to interpret the outcome of this or any experiment.

Nevertheless, when women were placed on lacto/ovo vegetarian diets, their intestinal iron absorption was reduced by 70%; however, inexplicably, blood ferritin levels (a marker of their long-term iron status) did not decline for the group as a whole. It should be noted that nearly half of the subjects did experience drops in blood ferritin concentrations. Because the authors of this study failed to include a control group, then extraneous variables likely swayed the experiment’s outcome. You recall from earlier in this essay that vegetarian diets caused 7 out of 9 women to stop ovulating. With the cessation of menstrual periods, monthly blood loses also cease which in turn prevents monthly iron losses because blood is a rich source of iron. Hence, in any study evaluating blood iron stores in women, it is absolutely essential to know if their normal menstrual cycles were altered. Unfortunately, Dr. Hunt did not provide us with this information, thereby making the correct interpretation of her experiment difficult or impossible.

In order to once and for all know whether or not vegetarian diets cause iron deficiencies, we would need to perform Dr. Hunt’s experiment again, for at least a year with more subjects, a control group and monitor changes in menstrual periods. You would think that this kind of very basic experimental evidence would have already been in place before any governmental or institutional organization told us that vegetarian diets were safe and didn’t cause nutritional deficiencies. Unfortunately, these precautionary steps have never been taken, and millions of Americans who adhere to vegetarian diets with the mistaken belief that they will benefit health-wise will actually suffer.

Iodine Deficiencies in Vegetarian Diets

A number of studies have reported that vegetarian and vegan diets increase the risk for iodine deficiency.40, 77, 102, 153 One study from Europe demonstrated that 80% of vegans and 25% of ovo/lacto vegetarians suffered from iodine deficiency.77 Additionally, a dietary intervention by Dr. Remer and colleagues in 1999 confirmed this epidemiological evidence.102 After only five days on ovo/lacto vegetarian diets, iodine status and function became impaired in healthy adults.102 The primary reason why vegetarian diets cause iodine deficiencies is that plant foods (except for seaweed) are generally poor sources of iodine compared to meat, eggs, poultry and fish. Gross deficiencies of iodine cause our thyroid glands to swell producing a condition known as goiter, and in pregnant women result in severe birth defects called cretinism.141 Because salt is fortified with iodine, most people in the U.S. and Europe rarely develop gross iodine deficiencies.40, 140, 141 However moderate to mild iodine deficiencies appear in westernized countries, particularly among vegetarians and vegans.77, 102 Moderate iodine deficiency impairs normal growth in children and adversely affects mental development.140, 141, 152 A large meta analysis revealed that moderate childhood iodine deficiency lowered I.Q. by 12-13.5 points.153 Paleo Diets are not just good medicine for adults, but they also ensure normal physical and mental development in our children because of their high iodine content.

One of the problems with plant based diets is that they may put into play a vicious cycle that makes iodine deficiencies worse. When the thyroid glands iodine stores become depleted, as often happens with vegetarian diets, then certain antinutrients found in plant foods can gain a foot hold and further aggravate iodine shortages. Soy beans and soy products are frequently a mainstay in vegetarian diets and may promote inflammation.66 Unfortunately soy contains certain antinutrients (isoflavones) that impair iodine metabolism in the thyroid gland,43, 95 but only when our body stores of iodine are already depleted. Other plant foods (millet, cassava root, lima beans, sweet potatoes, and cruciferous vegetables [broccoli, cauliflower, turnips, kale, cabbage]) also contain a variety of antinutrients which hinder normal iodine metabolism. So, plant based diets put us at risk for developing iodine deficiencies in the first place, and when this happens our bodies become vulnerable to plant antinutrients that worsen the pre-existing deficiency. The important point here is that antinutritional compounds have virtually zero effect upon our thyroid gland when our body stores of iodine are normal and fully replete. Because meats, fish, eggs and poultry are rich sources of iodine, you will never have to worry about this nutrient when you eat Paleo style.

Vitamin D and Vitamin B6 Deficiencies in Vegetarian Diets

In my paper, Cereal Grains: Humanity’s Double Edged Sword, I have pointed out how excessive consumption of whole grains adversely affects vitamin D status in our bodies.148 Hence it goes without saying that vitamin D deficiencies run rampant in vegetarians worldwide because it is nearly impossible to become a full-fledged vegetarian without eating lots of grains. In the largest study of vegetarians ever undertaken (The Epic-Oxford Study), Dr. Crowe and fellow researchers reported that blood concentrations of vitamin D were highest in meat eaters and lowest in vegans and vegetarians.29 Nearly 8% of the vegans maintained clinical deficiencies of vitamin D. Vitamin D is not really a vitamin at all, but rather a crucial hormone that impacts virtually every cell in our bodies.

By now, you are starting to get a pretty good picture of what a nutritional nightmare vegetarian diets really are. When we let the data speak for itself, the number of nutrient deficiencies and adverse health effects associated with plant based diets are appalling and far outweigh any supposed health effects of this unnatural way of eating. One of the biggest kept secrets about vegan or vegetarian diets is that they frequently cause vitamin B6 deficiencies. If you recall, neither the ADA,28 nor the USDA142 has given us any warning that meatless diets increase our risk for vitamin B6 deficiencies.

On paper, it would appear that vegetarian diets generally meet daily recommended intakes for vitamin B6. This assumption comes primarily from population surveys examining the foods that vegans and vegetarians normally eat. In contrast, when blood samples are analyzed from people relying upon plant based diets, they unexpectedly reveal that long term vegetarians and vegans frequently are deficient vitamin B6. A recent study of 93 German vegans by Dr. Waldman and colleagues showed that 58% of these men and women suffered from vitamin B6 deficiencies despite seemingly adequate intakes of this essential nutrient.131 It turns out that the type of vitamin B-6 (pyridoxine glucoside) found in plant foods is poorly absorbed.47, 103 The presence of pyridoxine glucoside in plant foods along with fiber has been reported to reduce the bioavailability of vitamin B6 so that only 20 to 25% is absorbed and completely utilized.47 In contrast, vitamin B6 found in animal foods is easily assimilated, and an estimated 75 to 100% fully makes its way into our bloodstreams.47

Compelling evidence that vegetarian diets relying upon the plant form of vitamin B6 adversely affect our body’s overall vitamin B6 stores comes from Dr. Leklem’s laboratory at Oregon State University.47 Nine women were put on diets either high or low in the plant form of vitamin B6 (pyridoxine glucoside). After only 18 days, the high pyridoxine glucoside diets consistently lowered blood concentrations and other indices of vitamin B6 status. Deficiencies in this vitamin elevate blood homocysteine concentrations and increase our risk for cardiovascular disease similar to shortages of folate and vitamin B12. Further, vitamin B6 is an important factor in normal immune system functioning149 and shortfalls of this crucial nutrient have been identified in depression150 and colorectal cancer.151

Omega 3 Fatty Acid Deficiencies in Vegetarian Diets

A few years ago I was involved in a series of experiments here at Colorado State University in which we were interested in determining how high and low salt diets affected exercise-induced asthma. Our working hypothesis was that high salt diets would make measures of lung function worse, and low salt diets would improve things. One of our concerns with this experiment was to somehow make sure our subjects had fully complied with either the high or low salt diets. Completely removing salt from your diet is not an easy thing to do, and if some of our subjects had decided to sneak in a piece of pizza or some Doritos, it would mess up the experiment’s outcome. Fortunately, there was an easy way to figure out if our subjects had been compliant with the prescribed diets. All we had to do was to spot check their urine, because measurement of urinary salt levels is an accurate gauge of dietary salt consumption. High urinary salt levels universally reflect high salt consumption, whereas low urinary salt concentrations indicate low salt consumption. Short of major disease, there is virtually no other way high amounts of salt in the urine don’t indicate high amounts of salt in the diet.

In a similar manner, there are equivalent telltale indicators of omega 3 fatty acids in our bloodstreams that tell us beyond a shadow of a doubt whether or not we have regularly consumed fish, seafood or other good sources these healthful fats. The three main types of omega 3 fatty acids we need to concern ourselves with are EPA, DHA and ALA. EPA and DHA are called long chain omega 3 fatty acids and are only found in high amounts in fish, seafood, certain meats, and other foods of animal origin. Plant foods contain no EPA or DHA. On the other hand, ALA is called a short chain fatty acid and is found in both plant and animal foods. Both EPA and DHA in our red blood cells are markers of these important fatty acids in our diet. Without good dietary sources of EPA and DHA such as are found in fish, seafood and certain meats, our blood levels of EPA and DHA will decline. Just like salt in our urine was an indicator for dietary salt, EPA and DHA concentrations in our red blood cells are markers for our dietary intake of these long chain omega 3 fatty acids. It is virtually impossible to achieve high blood levels of EPA and DHA without regularly consuming fish, seafood and certain meats and organ meats (particularly grass produced meats and organ meats).

One of the major nutritional shortcomings in vegans is that they obtain absolutely no EPA or DHA from their diets.108, 110, 111 Consequently, they are totally dependent upon plant based ALA, supplements or fortified foods to obtain these healthful long chain omega 3 fatty acids. Without supplements or fortified foods, all vegans will become deficient in EPA and DHA because plant based ALA is inefficiently converted into these long chain fatty acids in our bodies. The liver converts less than 5% of ALA into EPA and less than 1% of ALA into DHA.15, 97 Virtually every epidemiological study that has ever been published shows that vegans, who do not supplement or consume long chain omega 3 fortified foods, to be deficient in both EPA and DHA76, 88, 108, 110, 111 Lacto/ovo vegetarians don’t fare much better because milk and egg based vegetarian diets simply do not supply sufficient DHA or EPA to maintain normal blood concentrations.88, 111

There is little doubt that vegan or vegetarian diets cause reductions in blood concentrations of DHA and EPA, which in turn represent a potent risk factor for many chronic diseases. Perhaps the single most important dietary recommendation to improve your health and prevent illness is to increase your dietary intake of EPA and DHA. Thousands of scientific papers covering an assortment of diseases clearly show the health benefits of these fatty acids. In randomized clinical trials in patients with pre-existing heart disease, omega-3 fatty acid supplements significantly reduced cardiovascular events (deaths, non-fatal heart attacks, and non-fatal strokes).19, 48, 138 Omega-3 fatty acids lessen the risk for heart disease through a number of means including a reduction in heart beat irregularities called arrhythmias, a decrease in blood clots, and reduced inflammation which is now known to be an chief factor causing atherosclerosis or artery clogging.

In addition to lowering the risk for heart disease, regular consumption of fish or supplemental omega-3 fatty acids may be useful in averting, treating, or improving a wide range of diseases and disorders, including virtually all inflammatory diseases (any disease ending with “itis”): rheumatoid arthritis,99 inflammatory bowel disorders (Crohn’s disease, ulcerative colitis), periodontal disease (gingivitis). Also mental disorders (autism, depression),3, 84 postpartum depression, bi-polar disorder, borderline personality disorder, impaired cognitive development in infants and children) may respond favorably to these beneficial fatty acids. Further, acne, asthma, exercise induced asthma, many types of cancers,120 macular degeneration, pre-term birth, psoriasis, insulin resistance, type 2 diabetes, cancer cachexia, intermittent claudication, skin damage from sunlight, IgA nephropathy, lupus erythematosus, type 1 diabetes, multiple sclerosis, and migraine headaches also improve with omega 3 fatty acids.

Taurine deficiencies in Vegetarian Diets

Although the number of nutrients which are frequently lacking in vegetarian and vegan diets may seem endless to you, we are now at the end of the list. Taurine is an amino acid (actually a sulfonic acid because it lacks a carboxyl group) in our bloodstreams that has multiple functions in every cell of our body. Unfortunately, this nutrient is not present in any plant food and is found in low concentrations in milk (6 mg per cup).80 In contrast, all flesh foods are excellent sources of taurine.80 For example, ¼ pound of dark meat from chicken provides 200mg of taurine. Shellfish are even richer still with over 800mg per quarter pound. The daily taurine intake in non-vegetarians is about 150mg, whereas lacto/ovo vegetarians take in about 17mg per day, and vegans get none. Although our livers can manufacture taurine from precursor molecules, our capacity to do so is limited – so much so that this amino acid is regularly fortified in infant formulas. As you might expect, studies of vegans show that their blood taurine levels are lower than meat eaters.81, 100 How depleted blood concentrations of taurine affect our overall health, is not entirely understood. Nevertheless, shortages of this amino acid and omega 3 fatty acids (EPA and DHA) may cause certain elements (platelets) in our blood to clot more rapidly which in turn increase our risk for cardiovascular disease.85, 91 Despite their meat free diets, vegetarians almost always exhibit abnormal platelets that excessively adhere to one another. In one dietary intervention, Dr. Mezzano and colleagues demonstrated that after eight weeks of EPA and DHA supplementation normal platelet function was restored in a group of 18 lacto/ovo vegetarians.85 Obviously, compromised taurine status will never become a problem in Paleo Diets, because meat, fish, poultry and animal products are consumed at nearly every meal.

In summary, if you have adopted, or are considering adopting a plant based diet for reasons of improving your health, make sure you reread this chapter and look up all of the references I have provided you. The evidence that vegetarian and vegan diets almost always cause a multitude of nutritional deficiencies is overwhelming and conclusive. Over the course of a lifetime, vegetarian diets will not reduce your risk of chronic disease and will not allow you to live longer. Rather, this abnormal way of eating will predispose you to a host of health problems and illnesses. Vegetarianism is an unnatural way of eating that has no evolutionary precedence in our species. No hunter-gatherer society ever consumed a meatless diet, nor should you. The ADA has labeled The Paleo Diet a fad diet because it eliminates “two entire food groups” (grains and dairy). Yet hypocritically, they exempt vegan diets from this characterization despite also eliminating two food groups (dairy, meats and fish). If The Paleo Diet is a fad diet, then it is the world’s oldest.


Loren Cordain, Ph.D., Professor Emeritus


1. Alexander D, Ball MJ, Mann J. Nutrient intake and haematological status of vegetarians and age-sex matched omnivores. Eur J Clin Nutr. 1994 Aug;48(8):538-46.

2. Appleby P, Roddam A, Allen N, Key T. Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford. Eur J Clin Nutr. 2007 Dec;61(12):1400-6.

3. Appleton KM, Rogers PJ, Ness AR. Updated systematic review and meta-analysis of the effects of n-3 long-chain polyunsaturated fatty acids on depressed mood. Am J Clin Nutr. 2010 Mar;91(3):757-70

4. Baines M, Kredan MB, Davison A, Higgins G, West C, Fraser WD, Ranganath LR. The association between cysteine, bone turnover, and low bone mass. Calcif Tissue Int. 2007 Dec;81(6):450-4

5. Baines S, Powers J, Brown WJ. How does the health and well-being of young Australian vegetarian and semi-vegetarian women compare with non-vegetarians? Public Health Nutr. 2007 May;10(5):436-42.

6. Bhushan S, Pandey RC, Singh SP, Pandey DN, Seth P. Some observations on human semen analysis. Indian J Physiol Pharmacol. 1978 Oct-Dec;22(4):393-6.

7. Bennett M. Vitamin B12 deficiency, infertility and recurrent fetal loss. J Reprod Med. 2001 Mar;46(3):209-12.

8. Berker B, Kaya C, Aytac R, Satiroglu H. Homocysteine concentrations in follicular fluid are associated with poor oocyte and embryo qualities in polycystic ovary syndrome patients undergoing assisted reproduction. Hum Reprod. 2009 Sep;24(9):2293-302

9. Bissoli L, Di Francesco V, Ballarin A, Mandragona R, Trespidi R, Brocco G, Caruso B, Bosello O, Zamboni M. Effect of vegetarian diet on homocysteine levels. Ann Nutr Metab. 2002;46(2):73-9.

10. Bocherens H, Drucker DG, Billiou D, Patou-Mathis M, Vandermeersch B. Isotopic evidence for diet and subsistence pattern of the Saint-Cesaire I Neanderthal: review and use of a multi-source mixing model. J Hum Evol. 2005 Jul;49(1):71-87

11. Boivin J, Bunting L, Collins JA, Nygren KG. International estimates of infertility prevalence and treatment-seeking: potential need and demand for infertility medical care. Hum Reprod. 2007 Jun;22(6):1506-12.

12. Boxmeer JC, Smit M, Weber RF, Lindemans J, Romijn JC, Eijkemans MJ, Macklon NS, Steegers-Theunissen RP. Seminal plasma cobalamin significantly correlates with sperm concentration in men undergoing IVF or ICSI procedures. J Androl. 2007 Jul-Aug;28(4):521-7

13. Boxmeer JC, Brouns RM, Lindemans J, Steegers EA, Martini E, Macklon NS, Steegers-Theunissen RP. Preconception folic acid treatment affects the microenvironment of the maturing oocyte in humans. Fertil Steril. 2008 Jun;89(6):1766-70.

14. Boxmeer JC, Smit M, Utomo E, Romijn JC, Eijkemans MJ, Lindemans J, Laven JS, Macklon NS, Steegers EA, Steegers-Theunissen RP. Low folate in seminal plasma is associated with increased sperm DNA damage. Fertil Steril. 2009 Aug;92(2):548-56.

15. Brenna JT, Salem N Jr, Sinclair AJ, Cunnane SC. alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins Leukot Essent Fatty Acids. 2009 Feb-Mar;80(2-3):85-91.

16. Brown KH, Peerson JM, Baker SK, Hess SY. Preventive zinc supplementation among infants, preschoolers, and older prepubertal children. Food Nutr Bull. 2009 Mar;30(1 Suppl):S12-40.

17. Bucciarelli P, Martini G, Martinelli I, Ceccarelli E, Gennari L, Bader R, Valenti R, Franci B, Nuti R, Mannucci PM. The relationship between plasma homocysteine levels and bone mineral density in post-menopausal women. Eur J Intern Med. 2010 Aug;21(4):301-5

18. Bunn, HT, Kroll EM. Systematic butchery by Plio-Pleistocene hominids at Olduvai Gorge, Tanzania. Curr Anthropol 1986;20:365–398.

19. Calder PC, Yaqoob P. Omega-3 (n-3) fatty acids, cardiovascular disease and stability of atherosclerotic plaques. Cell Mol Biol (Noisy-le-grand). 2010 Feb 25;56(1):28-37.

20. Campbell-Brown M, Ward RJ, Haines AP, North WR, Abraham R, McFadyen IR, Turnlund JR, King JC. Zinc and copper in Asian pregnancies–is there evidence for a nutritional deficiency? Br J Obstet Gynaecol. 1985 Sep;92(9):875-85

21. Cappuccio FP, Bell R, Perry IJ, Gilg J, Ueland PM, Refsum H, Sagnella GA, Jeffery S, Cook DG. Homocysteine levels in men and women of different ethnic and cultural background living in England. Atherosclerosis. 2002 Sep;164(1):95-102.

22. Clarke R, Sherliker P, Hin H, Nexo E, Hvas AM, Schneede J, Birks J, Ueland PM, Emmens K, Scott JM, Molloy AM, Evans JG. Detection of vitamin B12 deficiency in older people by measuring vitamin B12 or the active fraction of vitamin B12, holotranscobalamin. Clin Chem. 2007 May;53(5):963-70

23. Clarke R. B-vitamins and prevention of dementia. Proc Nutr Soc. 2008 Feb;67(1):75-81.

24. Clarke R, Birks J, Nexo E, Ueland PM, Schneede J, Scott J, Molloy A, Evans JG. Low vitamin B-12 status and risk of cognitive decline in older adults. Am J Clin Nutr. 2007 Nov;86(5):1384-91.

25. Cogswell ME, Looker AC, Pfeiffer CM, Cook JD, Lacher DA, Beard JL, Lynch SR, Grummer-Strawn LM. Assessment of iron deficiency in US preschool children and nonpregnant females of childbearing age: National Health and Nutrition Examination Survey 2003-2006. Am J Clin Nutr. 2009 May;89(5):1334-42

26. Cordain L, Miller JB, Eaton SB, Mann N, Holt SH, Speth JD. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets.Am J Clin Nutr. 2000 Mar;71(3):682-92.

27. Cordain L, Campbell TC. The protein debate. Catalyst Athletics, March 19, 2008. http://www.cathletics.com/articles/article.php?articleID=50

28. Craig WJ, Mangels AR; American Dietetic Association. Position of the American Dietetic Association: vegetarian diets. J Am Diet Assoc. 2009 Jul;109(7):1266-82.

29. Crowe FL, Steur M, Allen NE, Appleby PN, Travis RC, Key TJ. Plasma concentrations of 25-hydroxyvitamin D in meat eaters, fish eaters, vegetarians and vegans: results from the EPIC-Oxford study. Public Health Nutr. 2011 Feb;14(2):340-6.

30. Dasarathy J, Gruca LL, Bennett C, Parimi PS, Duenas C, Marczewski S, Fierro JL, Kalhan SC. Methionine metabolism in human pregnancy. Am J Clin Nutr. 2010 Feb;91(2):357-65.

31. Davey GK, Spencer EA, Appleby PN, Allen NE, Knox KH, Key TJ. EPIC-Oxford: lifestyle characteristics and nutrient intakes in a cohort of 33 883 meat-eaters and 31 546 non meat-eaters in the UK. Public Health Nutr. 2003 May;6(3):259-69.

32. de Bortoli MC, Cozzolino SM. Zinc and selenium nutritional status in vegetarians. Biol Trace Elem Res. 2009 Mar;127(3):228-33.

33. de Heinzelin J, Clark JD, White T, Hart W, Renne P, WoldeGabriel G, Beyene Y, Vrba E. Environment and behavior of 2.5-million-year-old Bouri hominids. Science. 1999 Apr 23;284(5414):625-9

34. Dhonukshe-Rutten RA, van Dusseldorp M, Schneede J, de Groot LC, van Staveren WA. Low bone mineral density and bone mineral content are associated with low cobalamin status in adolescents. Eur J Nutr. 2005 Sep;44(6):341-7.

35. Dror DK, Allen LH. Effect of vitamin B12 deficiency on neurodevelopment in infants: current knowledge and possible mechanisms. Nutr Rev. 2008 May;66(5):250-5.

36. Ebisch IM, Peters WH, Thomas CM, Wetzels AM, Peer PG, Steegers-Theunissen RP. Homocysteine, glutathione and related thiols affect fertility parameters in the (sub)fertile couple. Hum Reprod. 2006 Jul;21(7):1725-33.

37. Ebisch IM, Pierik FH, DE Jong FH, Thomas CM, Steegers-Theunissen RP. Does folic acid and zinc sulphate intervention affect endocrine parameters and sperm characteristics in men? Int J Androl. 2006 Apr;29(2):339-45.

38. Elmadfa I, Singer I.Vitamin B-12 and homocysteine status among vegetarians: a global perspective. Am J Clin Nutr. 2009 May;89(5):1693S-1698S.

39. Falkingham M, Abdelhamid A, Curtis P, Fairweather-Tait S, Dye L, Hooper L.The effects of oral iron supplementation on cognition in older children and adults: a systematic review and meta-analysis. Nutr J. 2010 Jan 25;9:4.

40. Lightowler HJ, Davies GJ. Iodine intake and iodine deficiency in vegans as assessed by the duplicate-portion technique and urinary iodine excretion. Br J Nutr. 1998 Dec;80(6):529-35.

41. Fischer Walker CL, Ezzati M, Black RE. Global and regional child mortality and burden of disease attributable to zinc deficiency. Eur J Clin Nutr. 2009 May;63(5):591-7.

42. Food habits of a nation. In: The Hindu, August 14, 2006.

43. Fort P, Moses N, Fasano M, Goldberg T, Lifshitz F. Breast and soy-formula feedings in early infancy and the prevalence of autoimmune thyroid disease in children. J Am Coll Nutr. 1990 Apr;9(2):164-7.

44. Freeland-Graves JH, Ebangit ML, Hendrikson PJ. Alterations in zinc absorption and salivary sediment zinc after a lacto-ovo-vegetarian diet. Am J Clin Nutr. 1980 Aug;33(8):1757-66.

45. Freeland-Graves JH, Bodzy PW, Eppright MA. Zinc status of vegetarians. J Am Diet Assoc. 1980 Dec;77(6):655-61

46. Gilsing AM, Crowe FL, Lloyd-Wright Z, Sanders TA, Appleby PN, Allen NE, Key TJ. Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians and vegans: results from a cross-sectional analysis of the EPIC-Oxford cohort study. Eur J Clin Nutr. 2010 Sep;64(9):933-9

47. Hansen CM, Leklem JE, Miller LT. Vitamin B-6 status indicators decrease in women consuming a diet high in pyridoxine glucoside. J Nutr. 1996 Oct;126(10):2512-8

48. Harris WS, Kris-Etherton PM, Harris KA. Intakes of long-chain omega-3 fatty acid associated with reduced risk for death from coronary heart disease in healthy adults. Curr Atheroscler Rep. 2008 Dec;10(6):503-9.

49. Herbert V. Staging vitamin B-12 (cobalamin) status in vegetarians. Am J Clin Nutr. 1994 May;59(5 Suppl):1213S-1222S

50. Herrmann W, Obeid R, Schorr H, Geisel J. Functional vitamin B12 deficiency and determination of holotranscobalamin in populations at risk. Clin Chem Lab Med. 2003 Nov;41(11):1478-88.

51. Herrmann M, Widmann T, Colaianni G, Colucci S, Zallone A, Herrmann W. Increased osteoclast activity in the presence of increased homocysteine concentrations. Clin Chem. 2005 Dec;51(12):2348-53

52. Herrmann W, Schorr H, Obeid R, Geisel J. Vitamin B-12 status, particularly holotranscobalamin II and methylmalonic acid concentrations, and hyperhomocysteinemia in vegetarians. Am J Clin Nutr. 2003 Jul;78(1):131-6.

53. Herrmann M, Peter Schmidt J, Umanskaya N, Wagner A, Taban-Shomal O, Widmann T, Colaianni G, Wildemann B, Herrmann W. The role of hyperhomocysteinemia as well as folate, vitamin B(6) and B(12) deficiencies in osteoporosis: a systematic review. Clin Chem Lab Med. 2007;45(12):1621-32

54. Herrmann W, Obeid R, Schorr H, Hübner U, Geisel J, Sand-Hill M, Ali N, Herrmann M. Enhanced bone metabolism in vegetarians–the role of vitamin B12 deficiency. Clin Chem Lab Med. 2009;47(11):1381-7.

55. Heyland DK, Jones N, Cvijanovich NZ, Wong H. Zinc supplementation in critically ill patients: a key pharmaconutrient? JPEN J Parenter Enteral Nutr. 2008 Sep-Oct;32(5):509-19.

56. Hinton PS, Sinclair LM. Iron supplementation maintains ventilatory threshold and improves energetic efficiency in iron-deficient nonanemic athletes. Eur J Clin Nutr. 2007 Jan;61(1):30-9.

57. Hirwe R, Jathar VS, Desai S, Satoskar RS. Vitamin B12 and potential fertility in male lactovegetarians. J Biosoc Sci. 1976 Jul;8(3):221-7

58. Ho-Pham LT, Nguyen ND, Nguyen TV. Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis. Am J Clin Nutr. 2009 Oct;90(4):943-50.

59. Hotz C. Dietary indicators for assessing the adequacy of population zinc intakes. Food Nutr Bull. 2007 Sep;28(3 Suppl):S430-53.

60. Huang YC, Chang SJ, Chiu YT, Chang HH, Cheng CH. The status of plasma homocysteine and related B-vitamins in healthy young vegetarians and nonvegetarians. Eur J Nutr. 2003 Apr;42(2):84-90.

61. Humphrey LL, Fu R, Rogers K, Freeman M, Helfand M. Homocysteine level and coronary heart disease incidence: a systematic review and meta-analysis. Mayo Clin Proc. 2008 Nov;83(11):1203-12.

62. Hunt JR, Matthys LA, Johnson LK. Zinc absorption, mineral balance, and blood lipids in women consuming controlled lactoovovegetarian and omnivorous diets for 8 wk. Am J Clin Nutr. 1998 Mar;67(3):421-30.

63. Hunt JR, Roughead ZK. Nonheme-iron absorption, fecal ferritin excretion, and blood indexes of iron status in women consuming controlled lactoovovegetarian diets for 8 wk. Am J Clin Nutr. 1999 May;69(5):944-52

64. Hvas AM, Morkbak AL, Nexo E. Plasma holotranscobalamin compared with plasma cobalamins for assessment of vitamin B12 absorption; optimisation of a non-radioactive vitamin B12 absorption test (CobaSorb). Clin Chim Acta. 2007 Feb;376(1-2):150-4

65. Jathar VS, Hirwe R, Desai S, Satoskar RS. Dietetic habits and quality of semen in Indian subjects. Andrologia. 1976;8(4):355-8.

66. Jenkins DJ, Kendall CW, Connelly PW, Jackson CJ, Parker T, Faulkner D, Vidgen E. Effects of high- and low-isoflavone (phytoestrogen) soy foods on inflammatory biomarkers and proinflammatory cytokines in middle-aged men and women. Metabolism. 2002 Jul;51(7):919-24

67. Karabudak E, Kiziltan G, Cigerim N. A comparison of some of the cardiovascular risk factors in vegetarian and omnivorous Turkish females. J Hum Nutr Diet. 2008 Feb;21(1):13-22.

68. Katre P, Bhat D, Lubree H, Otiv S, Joshi S, Joglekar C, Rush E, Yajnik C. Vitamin B12 and folic acid supplementation and plasma total homocysteine concentrations in pregnant Indian women with low B12 and high folate status. Asia Pac J Clin Nutr. 2010;19(3):335-43.

69. Key TJ, Fraser GE, Thorogood M, Appleby PN, Beral V, Reeves G, Burr ML, Chang-Claude J, Frentzel-Beyme R, Kuzma JW, Mann J, McPherson K. Mortality in vegetarians and nonvegetarians: detailed findings from a collaborative analysis of 5 prospective studies. Am J Clin Nutr. 1999 Sep;70(3 Suppl):516S-524S.

70. Key TJ, Appleby PN, Rosell MS. Health effects of vegetarian and vegan diets. Proc Nutr Soc. 2006 Feb;65(1):35-41.

71. Key TJ, Appleby PN, Spencer EA, Travis RC, Roddam AW, Allen NE. Mortality in British vegetarians: results from the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford). Am J Clin Nutr. 2009 May;89(5):1613S-1619S

72. Key TJ, Appleby PN, Spencer EA, Travis RC, Roddam AW, Allen NE. Cancer incidence in vegetarians: results from the European Prospective Investigation into Cancer and Nutrition (EPIC-Oxford). Am J Clin Nutr. 2009 May;89(5):1620S-1626S

73. Khedr E, Hamed SA, Elbeih E, El-Shereef H, Ahmad Y, Ahmed S. Iron states and cognitive abilities in young adults: neuropsychological and neurophysiological assessment. Eur Arch Psychiatry Clin Neurosci. 2008 Dec;258(8):489-96. Epub 2008 Jun 20.

74. Koebnick C, Hoffmann I, Dagnelie PC, Heins UA, Wickramasinghe SN, Ratnayaka ID, Gruendel S, Lindemans J, Leitzmann C. Long-term ovo-lacto vegetarian diet impairs vitamin B-12 status in pregnant women. J Nutr. 2004 Dec;134(12):3319-26.

75. Knovich MA, Storey JA, Coffman LG, Torti SV, Torti FM. Ferritin for the clinician. Blood Rev. 2009 May;23(3):95-104

76. Kornsteiner M, Singer I, Elmadfa I. Very low n-3 long-chain polyunsaturated fatty acid status in Austrian vegetarians and vegans. Ann Nutr Metab. 2008;52(1):37-47

77. Krajcovicová-Kudlácková M, Bucková K, Klimes I, Seboková E. Iodine deficiency in vegetarians and vegans. Ann Nutr Metab. 2003;47(5):183-5.

78. Krivosíková Z, Krajcovicová-Kudlácková M, Spustová V, Stefíková K, Valachovicová M, Blazícek P, Nĕmcová T. The association between high plasma homocysteine levels and lower bone mineral density in Slovak women: the impact of vegetarian diet. Eur J Nutr. 2010 Apr;49(3):147-53

79. Kumar J, Garg G, Sundaramoorthy E, Prasad PV, Karthikeyan G, Ramakrishnan L, Ghosh S, Sengupta S. Vitamin B12 deficiency is associated with coronary artery disease in an Indian population. Clin Chem Lab Med. 2009;47(3):334-8.

80. Laidlaw SA, Grosvenor M, Kopple JD. The taurine content of common foodstuffs. JPEN J Parenter Enteral Nutr. 1990 Mar-Apr;14(2):183-8.

81. Laidlaw SA, Shultz TD, Cecchino JT, Kopple JD. Plasma and urine taurine levels in vegans. Am J Clin Nutr. 1988 Apr;47(4):660-3

82. Leboff MS, Narweker R, LaCroix A, Wu L, Jackson R, Lee J, Bauer DC, Cauley J, Kooperberg C, Lewis C, Thomas AM, Cummings S. Homocysteine levels and risk of hip fracture in postmenopausal women. J Clin Endocrinol Metab. 2009 Apr;94(4):1207-13

83. Lee-Thorp J, Thackeray JF, van der Merwe N. The hunters and the hunted revisited. J Hum Evol 2000; 39: 565–576.

84. Lin PY, Huang SY, Su KP. A meta-analytic review of polyunsaturated fatty acid compositions in patients with depression. Biol Psychiatry. 2010 Jul 15;68(2):140-7.

85. Mezzano D, Kosiel K, Martínez C, Cuevas A, Panes O, Aranda E, Strobel P, Pérez DD, Pereira J, Rozowski J, Leighton F. Cardiovascular risk factors in vegetarians. Normalization of hyperhomocysteinemia with vitamin B(12) and reduction of platelet aggregation with n-3 fatty acids. Thromb Res. 2000 Nov 1;100(3):153-60.

86. Molloy AM, Kirke PN, Brody LC, Scott JM, Mills JL. Effects of folate and vitamin B12 deficiencies during pregnancy on fetal, infant, and child development. Food Nutr Bull. 2008 Jun;29(2 Suppl):S101-11

87. Molloy AM, Kirke PN, Troendle JF, Burke H, Sutton M, Brody LC, Scott JM, Mills JL. Maternal vitamin B12 status and risk of neural tube defects in a population with high neural tube defect prevalence and no folic Acid fortification. Pediatrics. 2009 Mar;123(3):917-23.

88. Mann N, Pirotta Y, O’Connell S, Li D, Kelly F, Sinclair A. Fatty acid composition of habitual omnivore and vegetarian diets. Lipids. 2006 Jul;41(7):637-46

89. Mariani A, Chalies S, Jeziorski E, Ludwig C, Lalande M, Rodière M. [Consequences of exclusive breast-feeding in vegan mother newborn–case report]. Arch Pediatr. 2009 Nov;16(11):1461-3.

90. McCann JC, Ames BN. An overview of evidence for a causal relation between iron deficiency during development and deficits in cognitive or behavioral function. Am J Clin Nutr. 2007 Apr;85(4):931-45.

91. McCarty MF. Sub-optimal taurine status may promote platelet hyperaggregability in vegetarians.Med Hypotheses. 2004;63(3):426-33.

92. McClung JP, Karl JP, Cable SJ, Williams KW, Nindl BC, Young AJ, Lieberman HR. Randomized, double-blind, placebo-controlled trial of iron supplementation in female soldiers during military training: effects on iron status, physical performance, and mood. Am J Clin Nutr. 2009 Jul;90(1):124-31.

93. Michie CA, Chambers J, Abramsky L, Kooner JS. Folate deficiency, neural tube defects, and cardiac disease in UK Indians and Pakistanis. Lancet. 1998 Apr 11;351(9109):1105.

94. Misra A, Vikram NK, Pandey RM, Dwivedi M, Ahmad FU, Luthra K, Jain K, Khanna N, Devi JR, Sharma R, Guleria R. Hyperhomocysteinemia, and low intakes of folic acid and vitamin B12 in urban North India. Eur J Nutr. 2002 Apr;41(2):68-77.

95. Messina M, Redmond G. Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature. Thyroid. 2006 Mar;16(3):249-58.

96. Osendarp SJ, Murray-Kolb LE, Black MM. Case study on iron in mental development–in memory of John Beard (1947-2009). Nutr Rev. 2010 Nov;68 Suppl 1:S48-52. doi: 10.1111/j.1753-4887.2010.00331.x.

97. Plourde M, Cunnane SC. Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements. Appl Physiol Nutr Metab. 2007 Aug;32(4):619-34.

98. Pront R, Margalioth EJ, Green R, Eldar-Geva T, Maimoni Z, Zimran A, Elstein D. Prevalence of low serum cobalamin in infertile couples. Andrologia. 2009 Feb;41(1):46-50.

99. Proudman SM, Cleland LG, James MJ. Dietary omega-3 fats for treatment of inflammatory joint disease: efficacy and utility. Rheum Dis Clin North Am. 2008 May;34(2):469-79.

100. Rana SK, Sanders TA. Taurine concentrations in the diet, plasma, urine and breast milk of vegans compared with omnivores. Br J Nutr. 1986 Jul;56(1):17-27.

101. Refsum H, Yajnik CS, Gadkari M, Schneede J, Vollset SE, Orning L, Guttormsen AB, Joglekar A, Sayyad MG, Ulvik A, Ueland PM. Hyperhomocysteinemia and elevated methylmalonic acid indicate a high prevalence of cobalamin deficiency in Asian Indians. Am J Clin Nutr. 2001 Aug;74(2):233-41.

102. Remer T, Neubert A, Manz F. Increased risk of iodine deficiency with vegetarian nutrition. Br J Nutr. 1999 Jan;81(1):45-9.

103. Reynolds RD: Bioavailability of vitamin B-6 from plant foods. Am J Clin Nutr 1988;48:863-67.

104. Richards MP, Pettitt PB, Trinkaus E, Smith FH, Paunovic M, Karavanic, I. Neanderthal diet at Vindija and Neanderthal predation: The evidence from stable isotopes. Proc Natl Acad Sci 2000;97: 7663–7666.

105. Richards MP, Hedges REM, Jacobi R, Current, A, Stringer C. Focus: Gough’s Cave and Sun Hole Cave human stable isotope values indicate a high animal protein diet in the British Upper Palaeolithic. J Archaeol Sci 2000;27: 1–3.

106. Roe DA. History of promotion of vegetable cereal diets. J Nutr 1986;116:1355-1363.

107. Roed C, Skovby F, Lund AM. Severe vitamin B12 deficiency in infants breastfed by vegans]. Ugeskr Laeger. 2009 Oct 19;171(43):3099-101

108. Rosell MS, Lloyd-Wright Z, Appleby PN, Sanders TA, Allen NE, Key TJ. Long-chain n-3 polyunsaturated fatty acids in plasma in British meat-eating, vegetarian, and vegan men. Am J Clin Nutr. 2005 Aug;82(2):327-34.

109. Rush EC, Chhichhia P, Hinckson E, Nabiryo C. Dietary patterns and vitamin B(12) status of migrant Indian preadolescent girls. Eur J Clin Nutr. 2009 Apr;63(4):585-7. Epub 2007 Dec 19.

110. Sanders TA, Roshanai F. Platelet phospholipid fatty acid composition and function in vegans compared with age- and sex-matched omnivore controls. Eur J Clin Nutr. 1992 Nov;46(11):823-31.

111. Sanders TA. DHA status of vegetarians. Prostaglandins Leukot Essent Fatty Acids. 2009 Aug-Sep;81(2-3):137-41.

112. Sato Y, Honda Y, Iwamoto J, Kanoko T, Satoh K. Effect of folate and mecobalamin on hip fractures in patients with stroke: a randomized controlled trial. JAMA. 2005 Mar 2;293(9):1082-8.

113. Schneede J, Ueland PM. Novel and established markers of cobalamin deficiency: complementary or exclusive diagnostic strategies. Semin Vasc Med. 2005 May;5(2):140-55

114. Selhub J, Morris MS, Jacques PF. In vitamin B12 deficiency, higher serum folate is associated with increased total homocysteine and methylmalonic acid concentrations. Proc Natl Acad Sci U S A. 2007 Dec 11;104(50):19995-20000.

115. Shapin S. Vegetable love: the history of vegetarianism. New Yorker. 2007 Jan 22:80-4.

116. Singh K, Singh SK, Sah R, Singh I, Raman R. Mutation C677T in the methylenetetrahydrofolate reductase gene is associated with male infertility in an Indian population. Int J Androl. 2005 Apr;28(2):115-9.

117. Srikumar TS, Johansson GK, Ockerman PA, Gustafsson JA, Akesson B. Trace element status in healthy subjects switching from a mixed to a lactovegetarian diet for 12 mo. Am J Clin Nutr. 1992 Apr;55(4):885-90.

118. Stabler SP, Allen RH. Vitamin B12 deficiency as a worldwide problem. Annu Rev Nutr. 2004;24:299-326

119. Stephen EH, Chandra A. Declining estimates of infertility in the United States: 1982-2002. Fertil Steril. 2006 Sep;86(3):516-23.

120. Szymanski KM, Wheeler DC, Mucci LA. Fish consumption and prostate cancer risk: a review and meta-analysis. Am J Clin Nutr. 2010 Nov;92(5):1223-33.

121. Taneja S, Bhandari N, Strand TA, Sommerfelt H, Refsum H, Ueland PM, Schneede J, Bahl R, Bhan MK. Cobalamin and folate status in infants and young children in a low-to-middle income community in India. Am J Clin Nutr. 2007 Nov;86(5):1302-9.

122. te Velde E, Burdorf A, Nieschlag E, Eijkemans R, Kremer JA, Roeleveld N, Habbema D.
Is human fecundity declining in Western countries? Hum Reprod. 2010 Jun;25(6):1348-53.

123. Tikkiwal M, Ajmera RL, Mathur NK. Effect of zinc administration on seminal zinc and fertility of oligospermic males. Indian J Physiol Pharmacol. 1987 Jan-Mar;31(1):30-4.

124. van der Merwe NJ, Thackeray JF, Lee-Thorp JA, Luyt J. The carbon isotope ecology and diet of Australopithecus africanus at Sterkfontein, South Africa J Hum Evol 2003;44: 581–597.

125. van Meurs JB, Dhonukshe-Rutten RA, Pluijm SM, van der Klift M, de Jonge R, Lindemans J, de Groot LC, Hofman A, Witteman JC, van Leeuwen JP, Breteler MM, Lips P, Pols HA, Uitterlinden AG. Homocysteine levels and the risk of osteoporotic fracture. N Engl J Med. 2004 May 13;350(20):2033-41.

126. van Mil NH, Oosterbaan AM, Steegers-Theunissen RP. Teratogenicity and underlying mechanisms of homocysteine in animal models: a review. Reprod Toxicol. 2010 Dec;30(4):520-31.

127. Vegetarianism in American. Vegetarian Times Magazine, 2008. http://www.vegetariantimes.com/features/archive_of_editorial/667

128. Verkleij-Hagoort AC, Verlinde M, Ursem NT, Lindemans J, Helbing WA, Ottenkamp J, Siebel FM, Gittenberger-de Groot AC, de Jonge R, Bartelings MM, Steegers EA, Steegers-Theunissen RP. Maternal hyperhomocysteinaemia is a risk factor for congenital heart disease. BJOG. 2006 Dec;113(12):1412-8.

129. Vogel T, Dali-Youcef N, Kaltenbach G, Andrès E. Homocysteine, vitamin B12, folate and cognitive functions: a systematic and critical review of the literature. Int J Clin Pract. 2009 Jul;63(7):1061-7

130. Wald DS, Law M, Morris JK. Homocysteine and cardiovascular disease: evidence on causality from a meta-analysis. BMJ. 2002 Nov 23;325(7374):1202.

131. Waldmann A, Dörr B, Koschizke JW, Leitzmann C, Hahn A. Dietary intake of vitamin B6 and concentration of vitamin B6 in blood samples of German vegans. Public Health Nutr. 2006 Sep;9(6):779-84.

132. Wang Q, Yu LG, Campbell BJ, Milton JD, Rhodes JM. Identification of intact peanut lectin in peripheral venous blood. Lancet. 1998;352:1831-2

133. Werder SF. Cobalamin deficiency, hyperhomocysteinemia, and dementia. Neuropsychiatr Dis Treat. 2010 May 6;6:159-95

134. Whorton JC. Historical development of vegetarianism. Am J Clin Nutr 1994;59 (suppl) 1103S-9S.

135. Wilson AK, Ball MJ. Nutrient intake and iron status of Australian male vegetarians. Eur J Clin Nutr. 1999 Mar;53(3):189-94.

136. Wong WY, Merkus HM, Thomas CM, Menkveld R, Zielhuis GA, Steegers-Theunissen RP. Effects of folic acid and zinc sulfate on male factor subfertility: a double-blind, randomized, placebo-controlled trial. Fertil Steril. 2002 Mar;77(3):491-8.

137. Xavier D, Pais P, Devereaux PJ, Xie C, Prabhakaran D, Reddy KS, Gupta R, Joshi P, Kerkar P, Thanikachalam S, Haridas KK, Jaison TM, Naik S, Maity AK, Yusuf S; CREATE registry investigators. Treatment and outcomes of acute coronary syndromes in India (CREATE): a prospective analysis of registry data. Lancet. 2008 Apr 26;371(9622):1435-42.

138. Zhao YT, Chen Q, Sun YX, Li XB, Zhang P, Xu Y, Guo JH. Prevention of sudden cardiac death with omega-3 fatty acids in patients with coronary heart disease: a meta-analysis of randomized controlled trials. Ann Med. 2009;41(4):301-10.

139. Zhao JH, Sun SJ, Horiguchi H, Arao Y, Kanamori N, Kikuchi A, Oguma E, Kayama F.
A soy diet accelerates renal damage in autoimmune MRL/Mp-lpr/lpr mice. Int Immunopharmacol. 2005 Oct;5(11):1601-10.

140. Zimmermann MB. Iodine deficiency. Endocr Rev. 2009 Jun;30(4):376-408

141. Zimmermann MB. The adverse effects of mild-to-moderate iodine deficiency during pregnancy and childhood: a review. Thyroid. 2007 Sep;17(9):829-35.

142. United States Department of Agriculture (USDA). Choose My Plate. gov. Tips for Vegetarians, http://www.choosemyplate.gov/healthy-eating-tips/tips-for-vegetarian.html

143. Micha R, Mozaffarian D. Saturated fat and cardiometabolic risk factors, coronary heart disease, stroke, and diabetes: a fresh look at the evidence. Lipids. 2010 Oct;45(10):893-905.

144. Siri-Tarino PW1, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr. 2010 Mar;91(3):535-46.

145. Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Saturated fatty acids and risk of coronary heart disease: modulation by replacement nutrients. Curr Atheroscler Rep. 2010 Nov;12(6):384-90.

146. Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Saturated fat, carbohydrate, and cardiovascular disease. Am J Clin Nutr. 2010 Mar;91(3):502-9

147. Pirke KM, Schweiger U, Laessle R, Dickhaut B, Schweiger M, Waechtler M. Dieting influences the menstrual cycle: vegetarian versus nonvegetarian diet. Fertil Steril. 1986 Dec;46(6):1083-8.

148. Cordain L. Cereal grains: humanity’s double-edged sword. World Rev Nutr Diet. 1999;84:19-73.

149. Rall LC, Meydani SN. Vitamin B6 and immune competence. Nutr Rev. 1993 Aug;51(8):217-25.

150. Folstein M, Liu T, Peter I, Buell J, Arsenault L, Scott T, Qiu WW.The homocysteine hypothesis of depression. Am J Psychiatry. 2007 Jun;164(6):861-7.

151. Zhang XH, Ma J, Smith-Warner SA, Lee JE, Giovannucci E. Vitamin B6 and colorectal cancer: current evidence and future directions. World J Gastroenterol. 2013 Feb 21;19(7):1005-10

152. Bougma K1, Aboud FE, Harding KB, Marquis GS. Iodine and mental development of children 5 years old and under: a systematic review and meta-analysis. Nutrients. 2013 Apr 22;5(4):1384-416.

153. Zimmermann MB. The effects of iodine deficiency in pregnancy and infancy. Paediatr Perinat Epidemiol. 2012 Jul;26 Suppl 1:108-17

Wheat | The Paleo Diet

Dr. David Perlmutter, author of The New York Times bestselling Grain Brain, article in The Daily Beast is spot on: “Wheat Threatens All Humans.”  Nevertheless, wheat germ agglutinin or WGA has not yet been shown to appear in human blood following its ingestion.  Our research group actually performed the only experiment that has ever been conducted in humans with WGA consumption, published in the FASEB Journal and our poster presentation in 2010 at Experimental Biology, and we came up empty handed.  We collaborated with Franz Gabor’s group from Austria who had previously developed an ELISA for WGA, and we sent our frozen plasma samples to them for analysis.  We drew venous blood in 14 subjects over a 24 hr period following ingestion of 50 g of wheat germ (the highest natural dietary concentration of WGA) and found no WGA in plasma.

However, like Columbus sailing to the new world, we had absolutely no prior direction in our experiment.  We now believe our experiment was fatally flawed.  Notice in the poster that we presented the major proteins in plasma, and none of them bind WGA.  In fact of the more than 60  proteins found in plasma, only one binds WGA and that protein represents <0.1 % of all plasma proteins.

Accordingly, we were almost certainly looking in the wrong place for WGA.  When we spun down whole venous blood and threw out the formed elements (erthrocytes, WBCs and platelets), we threw out the baby with the bath water.  In all likelihood WGA breeches the gut barrier by first binding to the gut glycocalyx (which causes it to be shed) and  subsequently WGA now has access to the gut epithelial cells, dendritic cells and M cells.

At this point, it is unclear whether WGA takes a transcellular, paracellular (or both) journey allowing it to gain entry into lymph and then into venous blood, where it binds RBCs, WBCs, platelets and other formed elements and thereby gains access to virtually every cell in the body.  Arpad Pustzai group’s earlier work in animal models supports this concept, however they employed concentrations of WGA that could never be achieved via consumption of naturally occuring WGA in whole wheat bread or even wheat germ.

So, tantalizingly, the article still cannot be substantiated by any human experiments.  We would like to perform our experiment once again and analyze WGA in the blood formed elements — but unfortunately have no funding to do this experiment.  One of the most important nutritional/ health experiments for all of humanity has yet to be conducted.

On another note, not only does wheat contain gliadin, which upregulates zonulin, which increases intestinal permeability, it also contains an obscure compound (thaumatin like proteins) which also increase intestinal permeability.  Hence wheat represents a triple time bomb (gliadin, WGA and thaumatin like proteins) which maintain physical and physiological characteristics that almost certainly impair gut function, interact with our immune systems to produce low level inflammation, and impair vitamin D metabolism (not a vitamin at all, but a hormone having receptors in virtually every cell in the body).

In vitro studies show that WGA binds the nuclear pore and prevents vitamin D from causing its normal gene transcription — not a good thing as proper vitamin D metabolism is protective against osteoporosis, cancer, heart disease and all cause mortality.  Hence, as Dr. Perlmutter has suggested, it is likely that wheat consumption will eventually be recognized as a potent health risk for us all, similar to cigarette smoking which was first identified at the population level in the Surgeon General’s recommendations of the early 1960s.


Loren Cordain, Ph.D., Professor Emeritus

Fibromyalgia, Pregnancy, Calcium | The Paleo Diet

Hello Dr. Cordain,

I was wondering if you would tell me if I can start The Paleo Diet while pregnant? I’m coming up to 17 weeks and suffer from Fibromyalgia. My doctor recommended this diet regiment. He advised I cut out pulses, which I eat a lot of, and wheat, which I don’t often eat much of, and to cut dairy products. But, I thought calcium intake was very important during pregnancy? I also use soy milk in cereals and the soy shakes. I was told to stop consuming all of these foods for a month or so to see how I feel. My stomach feels less bloated and I feel better, but feel I may need longer than a month on this diet to relieve aches and pains induced by my condition. I know some people suffer terribly from Fibromyalgia everyday, but my symptoms come and go. I look forward to hearing from you.


Dr. Cordain’s Response:


The Paleo Diet excludes all grains, dairy, legumes, soy, sugar, unbalanced oils, and processed foods. The Paleo Diet emphasizes eating nutrient dense anti-inflammatory food that is derived from the earth in an unprocessed state. These foods include sustainably raised meat, fruit, vegetables, seeds, nuts, and healthy oils like coconut and olive.

Fibromyalgia is characterized by chronic and sometimes severe pain throughout the entire human body. Its exact cause has yet to be determined, but many people have had success healing their Fibromyalgia with The Paleo Diet.

I would strongly advise you to cut out wheat, dairy, and soy to treat your condition and to reduce overall inflammation in your body. Many people believe that soy milk is a healthy alternative to dairy-based milk for meeting the human calcium requirement. In reality, soy milk has many harmful properties that can actually inhibit absorption of calcium and other vital minerals and nutrients. Increasing you intake of fish is not only a good source of calcium, but it is also very rich in Omega-3 which is essential to development.

Many individuals who adopt The Paleo Diet question whether their calcium intake is sufficient, especially during pregnancy if dairy products are not permitted.

Foods that Naturally Contain High Levels of Calcium and Magnesium

  • Sardines
  • Salmon
  • Other small fish with soft cooked bones
Leafy Greens
  • Spinach
  • Kale
  • Lettuce chard
  • Arugula
Bone Broth
Dried Fruit
  • Apricots
  • Figs

All of the options above should provide your body with an adequate amount of calcium. It’s also worth mentioning that Vitamin D is an absolutely necessary component for synthesizing calcium and magnesium. Modern society emphasizes a lifestyle that is based on “indoor” activities. You can take all the calcium your heart desires, but if you are deficient in Vitamin D your calcium levels can still remain deficient!

The number one source of Vitamin D is sunlight. Spending only twenty minutes a day in full sunlight can provide your body with the necessary levels of vitamin D required for synthesizing calcium. If you live at a latitude that receives little sunlight, or if you lead a busy lifestyle that prevents you from getting outdoors, than you should take a Vitamin D supplement. A dosage of 2000 IU of Vitamin D per day is adequate for most adults. If you still feel that you are unable to meet your calcium requirements, you may want to consider taking a calcium supplement or drinking pure water that has been fortified with calcium.


Loren Cordain, Ph.D., Professor Emeritus

Affiliates and Credentials

Sign up for Email Newsletters!

We guarantee 100% privacy.
Your information will not be shared.