One of the numerous benefits from eating “Paleo” or switching to a contemporary Paleo Diet if you eat in the standard American way is that you and your spouse/partner/ will greatly improve your chances for successful conception, pregnancy and a healthy baby. Here’s the information you may want to become acquainted with, particularly if you have avoided meats and fish and have previously focused upon whole grain cereals, legumes and processed foods in your diet.
If you fail to regularly eat animal foods (eggs, meat, fish and seafood) you will become deficient in vitamin B12 because plant food sources contain no B12. Further plant foods do not contain the specific types of vitamin B6 which are readily absorbable in the human gut. Accordingly, diets devoid of or lacking in animal proteins, will invariably be deficient in vitamin B12 and vitamin B6. Deficiencies or insufficiencies in these vitamins ultimately increase the level of homocysteine in our blood.
Elevated blood concentrations of homocysteine result primarily from too little vitamin B12. B6 and folate in our diets. When adequate stores of these B vitamins are present from nutritious foods in our diet (e.g. meats, fresh fruits and veggies), then our cells can defuse the poisonous effects of homocysteine and convert it into less toxic compounds. However, when B12 is lacking or deficient, as it almost always is in vegetarian and vegan diets, then homocysteine builds up in our bloodstream and literally infiltrates nearly every cell in our bodies.
Healthy egg cells in women and healthy sperm cells in men are absolutely essential requirements for getting pregnant, staying pregnant and producing normal embryos, vigorous infants and healthy children. Vitamin B12 deficiencies can elevate blood levels of homocysteine and cause numerous adverse health problems in pregnant women, their unborn fetuses and nursing infants. In addition to these unfavorable effects, a diet deficient or marginal in vitamins B12, B6 and folate can severely reduce your chances for successful fertilization and conception.
Infertility is a huge problem in both the U.S. and Europe and affects at least 6 million people in the U.S. or more importantly about 7.4 % of the reproductive age population. Many environmental and genetic factors may be involved. However, one thing is certain, as a couple, if you or your partner’s blood levels of vitamin B12, B6 and/or folate are low and your homocysteine is elevated, your chances for normal conception will be significantly reduced.
It is becoming increasingly evident that the low vitamin B12, B6 and folate status responsible for elevated homocysteine is toxic to both sperm and egg cells and may represent a major, previously un-recognized risk factor for infertility. More than 30 years ago, at least one group of researchers pointed out that Indian vegetarian men maintained lower vitamin B12 concentrations in their sperm than non-vegetarians and attributed these values to their vegetarian diet. Additionally, a number of these earlier studies hinted that vitamin B12 supplementation could improve sperm function and vigor and even boost male fertility.
If we fast forward to the 21st century, in the past five years similar nutritional patterns have been discovered in western populations. In a recent (2009) study of 172 men and 223 women who were unable to conceive, 36 % of men and 23 % of women had vitamin B12 deficiencies. Almost 40 % of the infertile men had abnormal semen that was directly related to their vitamin B12 deficiencies. Other recent studies in men show that low dietary folate and vitamin B12 are associated with high blood concentrations of homocysteine that likely underlie abnormal sperm function. On the flip side of the equation, women with compromised dietary B12 and folate intakes frequently have elevated blood levels of homocysteine which prevent them from becoming pregnant. We are not completely sure how these blood chemistry changes impede successful pregnancies in women, but tissue studies suggest that egg cells infiltrated by homocysteine and deficient in vitamin B12 and folate make them fragile and unable to continue with a normal pregnancy once fertilized.
Menstrual Problems caused by Vegetarian and Low Meat Diets
In addition to B vitamin deficiencies and elevated blood concentrations of homocysteine, vegetarian/low meat diets are frequently associated with menstrual problems known to affect fertility. A total of five studies have compared the incidence of menstrual irregularities between vegetarians and meat eaters. Four out of these five studies demonstrated significantly higher rates of menstrual complications in vegetarians. Let’s take a look at the only randomized controlled trial investigating vegetarian diets on menstrual health.
Dr. Pirke and researchers at the University of Trier in Germany randomly divided 18 young women with normal menstrual periods into either vegetarian or non-vegetarian diet groups. After six weeks, 7 of the 9 women assigned to the vegetarian diet stopped ovulating, whereas only a single woman in the meat eating group experienced this problem. The results of this experiment are shocking – within only six weeks of consuming a vegetarian diet, 78% of healthy, normally cycling women ceased ovulating. The take home message is this: if you are trying to get pregnant, one of your best strategies is to avoid vegetarian diets. While you’re at it, make sure your husband or partner does the same.
Zinc Deficiencies Impair Sperm Function
One of the most frequent nutritional shortcomings of vegetarian and vegan diets is that they fall short of recommended intakes for zinc. In the largest epidemiological study ever of vegetarians (The EPIC-Oxford Study) Dr. Davey and colleagues noted that vegans had “. . . the lowest intakes of retinol [vitamin A], vitamin B12, vitamin D, calcium and zinc. . .” when compared to meat and fish eaters. More importantly, with zinc it’s not just how much is present in your food, but how much is actually absorbed in your body. Although dietary zinc intakes in vegetarian diets sometimes appear to be adequate on paper – in the body they actually result in deficiencies because most of plant based zinc is bound to phytate and therefore unavailable for absorption. Phytate is an antinutrient found in whole grains, beans, soy and other legumes that prevents normal assimilation of many minerals. Laboratory experiments show that vegetarians only absorb about half as much zinc as meat eaters because zinc from animal food is much better assimilated than from plant foods.
Based upon this information, you might expect blood concentrations of zinc to be lower in vegetarians than meat eaters. Sometimes scientists have found this to be the case, but not always. The problem here has to do with where zinc ends up in our bodies after we ingest it. Most zinc finds its way into the interior of cells and does not accumulate in the liquid portion (plasma) of blood. Consequently, unless scientists examine zinc concentrations within cells, readings obtained in blood plasma frequently do not accurately reflect body stores of this essential mineral. In virtually every study of vegetarians which measured zinc levels inside various cells (red blood cells, hair cells and skin cells in saliva), plant based diets caused zinc deficiencies. In one study, 12 meat eating women were put on a lacto-ovo vegetarian diet, and after only 22 days Dr. Freeland-Graves and co-workers reported that zinc concentrations in the women’s salivary cells plunged by 27%. Similar results were described by Dr. Srikumar and colleagues from a longer term experiment in which 20 meat eating men and women adopted a lactovegetarian diet for an entire year. In this study, both hair cells and blood levels of zinc sharply declined and remained low throughout the 12 month experiment.
So, I’ve set the stage for zinc deficiencies and infertility problems. Because of their low zinc content and bioavailability, long term vegetarian diets almost always cause zinc deficiencies. Numerous epidemiological studies have shown that infertile men had poor sperm counts that were associated with reduced zinc levels in their semen. Virtually every well controlled experimental study ever conducted shows that men put on zinc deficient diets ended up with reduced sperm counts, impaired sperm health and often depressed blood testosterone levels. The good news is that these deleterious changes in male reproductive function can be reversed if zinc rich diets (e.g. The Paleo Diet) are consumed, or if zinc pills are supplemented. Dr. Steegers-Theunissen’s research group in the Netherlands showed dramatic improvements in the reproductive health of 103 sub-fertile men when zinc and folic acid were supplemented. Following the six month supplementation program, sperm counts increased significantly in the sub-fertile men while sperm abnormalities declined by 4 %. A similar study of 14 infertile men from India also indicated that zinc supplementation increased sperm health, sperm counts and shortly thereafter resulted in three successful conceptions by these men’s wives.
Whether you are a man or woman, if you want to sidestep infertility problems, the best advice I can give you is to abandon vegetarian/low meat diets and adopt the nutritional patterns that have sustained our hunter-gatherer ancestors for the past 2.6 million years. There are no known risks to adopting The Paleo Diet, and in fact, regular consumption of meat, seafood and fresh fruit and vegetables at the expense of cereals, dairy and processed foods will prevent vitamin B12 and folate deficiencies. In turn these essential vitamins will ensure that your blood levels of homocysteine will return to normal – effectively reducing your risk for cardiovascular, neurological, bone and reproductive diseases.
Loren Cordain, Ph.D., Professor Emeritus
Dr. Loren Cordain is Professor Emeritus of the Department of Health and Exercise Science at Colorado State University in Fort Collins, Colorado. His research emphasis over the past 20 years has focused upon the evolutionary and anthropological basis for diet, health and well being in modern humans. Dr. Cordain’s scientific publications have examined the nutritional characteristics of worldwide hunter-gatherer diets as well as the nutrient composition of wild plant and animal foods consumed by foraging humans. He is the world’s leading expert on Paleolithic diets and has lectured extensively on the Paleolithic nutrition worldwide. Dr. Cordain is the author of six popular bestselling books including The Real Paleo Diet Cookbook, The Paleo Diet, The Paleo Answer, and The Paleo Diet Cookbook, summarizing his research findings.
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