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One 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.

References:

[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.

About The Author

Dr. Cordain is the founder of The Paleo Diet.

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