Vegetarians can't get all the B12 they need from plant sources

greenspun.com : LUSENET : Countryside : One Thread

http://www.mercola.com/2002/jan/26/vegetarianism_myths_02.htm

longyear@shentel.net), January 26, 2002

Answers

For some unknwn reason, my first post didn't include the article. You Can't Get All the Vitamin B12 You Need From Plant Sources By Stephen Byrnes, PhD, RNCP This article is one part of a series of articles that will run over several weeks. The article is actually a revision of an older article that we had previously posted on our site. You can find the original article here. Additionally, each article will be posted along with a rebuttal by Dr. Michael Janson. You can find the rebuttal to this article here. Part 2 of 15 (Previous) Myth #2: Vitamin B12 can be obtained from plant sources. Of all the myths, this is perhaps the most dangerous. While lacto and lacto-ovo vegetarians have sources of vitamin B12 in their diets (from dairy products and eggs), vegans (total vegetarians) do not. Vegans who do not supplement their diet with vitamin B12 will eventually get anemia (a potentially fatal condition) as well as severe nervous and digestive system damage; most, if not all, vegans have impaired B12 metabolism and every study of vegan groups has demonstrated low vitamin B12 concentrations in the majority of individuals (11). Several studies have been done documenting B12 deficiencies in vegan children, often with dire consequences (12). Additionally, claims are made in vegan and vegetarian literature that B12 is present in certain algae, tempeh (a fermented soy product) and Brewer's yeast. All of them are false as vitamin B12 is only found in animal foods. Brewer's and nutritional yeasts do not contain B12 naturally; they are always fortified from an outside source. There is not real B12 in plant sources but B12 analogues -- they are similar to true B12, but not exactly the same and because of this they are not bioavailable (13). It should be noted here that these B12 analogues can impair absorption of true vitamin B12 in the body due to competitive absorption, placing vegans and vegetarians who consume lots of soy, algae, and yeast at a greater risk for a deficiency (14). Some vegetarian authorities claim that B12 is produced by certain fermenting bacteria in the lower intestines. This may be true, but it is in a form unusable by the body. B12 requires intrinsic factor from the stomach for proper absorption in the ileum. Since the bacterial product does not have intrinsic factor bound to it, it cannot be absorbed (15). It is true that Hindu vegans living in certain parts of India do not suffer from vitamin B12 deficiency. This has led some to conclude that plant foods do provide this vitamin. This conclusion, however, is erroneous as many small insects, their feces, eggs, larvae and/or residue, are left on the plant foods these people consume, due to non- use of pesticides and inefficient cleaning methods. This is how these people obtain their vitamin B12. This contention is borne out by the fact that when vegan Indian Hindus later migrated to England, they came down with megaloblastic anaemia within a few years. In England, the food supply is cleaner, and insect residues are completely removed from plant foods (16). The only reliable and absorbable sources of vitamin B12 are animal products, especially organ meats and eggs (17). Though present in lesser amounts than meat and eggs, dairy products do contain B12. Vegans, therefore, should consider adding dairy products into their diets. If dairy cannot be tolerated, eggs, preferably from free-run hens, are a virtual necessity. That vitamin B12 can only be obtained from animal foods is one of the strongest arguments against veganism being a "natural" way of human eating. Today, vegans can avoid anemia by taking supplemental vitamins or fortified foods. If those same people had lived just a few decades ago, when these products were unavailable, they would have died. Please see the next issue of the newsletter for our continuation of this article. To read the rebuttal of the above article, please click here. DR. BYRNES' COMMENT: At the outset, something needs to be said regarding Dr. Janson’s frequent accusations that I “provide no references.” It is well-known that my paper is being published in SEGMENTS and, accordingly, not all of my references are revealed at one time, but they will be as more of the paper is published. His implications that my arguments have no foundation are therefore misleading, unfair, and deceptive to the reader. It needs to be re-emphasized to the reader that Dr. Janson’s advocated diet is NOT a vegetarian diet. Despite all of his double-talk to downplay the inclusion of animal foods in human diets, the point is that he still includes them. He states that humans only “need a small amount of [animal foods] to provide adequate vitamin B12 to cover basic human needs.” Given the difficulty with which people absorb vitamin B12 and the many variable factors that affect its absorption (hydrochloric acid, intrinsic factor, thyroid hormone, and calcium), Dr. Janson’s advice is misleading at best and dangerous at worst, given the known consequences of vitamin B12 deficiency (1). He then states that any supposed inadequacies in B12 intake can be met, not by eating more animal foods, but by taking vitamin pills. Is this his answer to the inadequacies of vegetarian and vegan diets? How did our ancestors survive before vitamin pills existed? By eating adequate animal foods, that’s how. Instead of recommending the natural solution to the B12 problem, he advises us to forsake healthful foods and pop pills--an unnatural solution, indeed. Dr. Janson’s comments on vegetarian diets and proneness to miscarriages deserve comment. In the first place, Dr. Janson seems to think that miscarriages are a “normal” occurrence for human females. Once again, is it really normal? The fact that Dr. Janson has had miscarriages in both the dilapidated health modern peoples suffer from. There is nothing “normal” or “routine” about this. It does, however, speak volumes about what women need to do to remedy the situation: eat more animal foods. Dr. Janson’s beliefs that vegetarian diets are better for women who are either pregnant or want to be pregnant are questionable. Studies have shown that vegetarian women suffer from greater menstrual irregularity than evenly matched omnivorous women. At the Milton S. Hershey Medical Center, only 4.9% of premenopausal omnivorous women suffered from menstrual irregularity, compared to a whopping 26.5% in vegetarian women (2). The probability of menstrual regularity was associated positively with protein and cholesterol intake and negatively with dietary fiber and magnesium intake. Such results are consistent with the hypothesis that premenopausal vegetarian women have circulating estrogen concentrations (3). Therefore, these women may also have decreased reproductive capacity (2). Another study at the Hershey Medical Center revealed that the frequency of menstrual irregularity was significantly higher in a lacto-ovo vegetarian group of women than in a matched group of nonvegetarian women (3). Furthermore, since studies have shown that vegetarians have higher homocysteine levels than non-vegetarians (4) and since homocysteine is a known cause of birth defects (5), it is certainly conceivable that vegetarian diets can and do predispose women to greater risks of miscarriages. Lastly, it is also known that vitamin B12 deficiency causes reproductive failure (6). Since vegans, in general, have impaired B12 metabolism and inadequate B12 intake (7), it is certainly likely that vegan women are more at risk for miscarriages. Dr. Janson’s statement that, “The body manufactures vitamin A from carotene, which is abundant in a diet high in fruits and vegetables,” shows his lack of knowledge on this subject. The carotene/vitamin A issue is dealt with further along in my article under myth #4 so I will not go into this too much here. Suffice it to say, that carotene is not vitamin A and that the conversion of carotenes into active vitamin A by the body is not an “automatic” occurrence as Dr. Janson implies. The conversion can only take place if several factors are present: bile, intestinal lipase, thyroid hormone, dietary fat, and proper liver function (8). Furthermore, diabetics and infants either cannot make the conversion, or do so very poorly. Lastly, it takes approximately six units of carotene to make just one unit of vitamin A--hardly an optimal conversion (8). This, of course, emphasizes the need to have adequate sources of vitamin A in our daily diets and this nutrient is only found in animal foods and fats. His attempt to compare gorilla physiology to human physiology is misleading: Humans are not gorillas. Furthermore, all primates eat meat (9), even gorillas. Gorillas will prefer more meat when in captivity, probably because more of it is available than in the wild (10). So Dr. Janson’s attempt to persuade readers to adopt a more gorilla-like diet is off-base. Dr. Janson’s warnings about mercury poisoning from fish are curious given that he himself eats fish and recommends the same to readers. He then, again, recommends supplements of fish oil over real food to get one’s EPA and DHA. I like to think that the health-conscious consumer will make the effort to obtain clean food sources of plants and animals and not have to rely on supplements to meet their nutritional needs. For the remainder of the rebuttal and the footnotes, go to the link: http://www.mercola.com/2002/jan/26/vegetarianism_myths_02.htm

longyear@shentel.net), January 26, 2002.

Good article. I've learned a lot from Dr. Mercola. Have been a veggie and experienced the bad results.

Some veggies use the excuse that animal food is too polluted for consumption. Well, they should support the naturally-raised products.

If everyone would just produce their own eggs, it would stop the incredible suffering of chickens who provide the store eggs. You'd think the SPCA would look into that.

I no longer buy the store eggs. If I need more eggs than my few chickens can produce, there are always neighbors who are selling.

-- HV (veggie@ourplace.com), January 26, 2002.


All I can say is there have been vegetarians who have lived to 90+ and there have been meat eaters who have lived to 90+. In my opinion how healthy you are and how long you live is all in your geans.

-- TomK(mich) (tjk@cac.net), January 26, 2002.

One can play whatever games one want to, but everyone succumbs to something. Take whatever consolation you like that life was ended by x and not y. My philosophy is: Die, and let die.

-- paul (primrose@centex.net), January 26, 2002.

Moderation questions? read the FAQ