Being Vegetarian: Is It Good or Bad for You?

Vegetarianism is the practice of observing a diet that consists of vegetables, grains, fruits, and nuts, and excludes meat and fowl. Vegetarians hold differing views about fish and those foods derived from animal products, such as milk, eggs, butter, and cheese.

The word vegetarian was first used in the 1840’s, although the practice of vegetarianism goes back thousands of years. People are influenced to follow this diet for a number of reasons – religious and moral, hygienic and physiological. Certain Hindu and Buddhist groups, Seventh-Day Adventist, and some Roman Catholic orders are among the religious group abstaining from meat. Some people feel that life is sacred to all living creatures and that it is ethically wrong to shorten the life-span of any animal to obtain food. Some vegetarians believe that the flesh of dead animals may harbor disease-causing bacteria and other impurities, and that no animals flesh can be as pure as plants grown by nature.

Nutritionally, a diet without meat, fish, or dairy products could be lacking in in protein, an essential nutrient for body-building and tissue repair. Great care must be taken in such a diet to emphasized foods rich in protein, such as  nuts and the seeds of legumes (peas, beans, lentils). It is also possible to buy specially prepared food supplements. In 1847 the Vegetarian Society was established in Manchester, England, the first group of this kind. In the early 20th century the International Vegetarian union was founded. It has affiliated societies through out the world.

Vegetarian Lack the Vital Vitamin B12

B12 is found almost exclusively in animal foods such as liver, kidney, meat, fish, shellfish, milk products and eggs but the original source of B12 in nature is bacteria, the only creatures able to manufacture this vitamin. In humans and animals, these bacteria produce B12 in the colon; however, little if any is absorbed across the colon wall so we must get our B12 from animal foods. Bivalves such as clams, mussels and oysters contain high levels of B12 because they siphon large quantities of vitamin B12-synthesizing microorganisms from the sea.³ Production of B12 supplements involves fermentation procedures similar to those used for penicillin and other antibiotics.

Interestingly, while eggs contain B12, they also contain substances that block absorption,¹ a fact that leaves only milk as a good source of B12 for vegetarians. Some studies indicate that B12 is better absorbed from milk than from meat.² However, one source indicates that B12 in milk is destroyed by boiling.³ Analysis of B12 in pasteurized milk reveals only a 10 percent loss; however pasteurization deforms the milk proteins that aid in B12 absorption.⁴

Interestingly, some sources claim that fermentation of yoghurt from milk lowers B12 levels,⁵ although food tables indicate similar levels in commercial milk and yoghurt.

The vitamin B12 molecule is resistant to temperatures in excess of the boiling point, unless exposed to an alkaline medium. The molecule breaks down at 250^o C. Thus B12 is destroyed on the surface of grilled meat, but not in the interior. Eight percent of B12 in liver is lost by boiling for five minutes.⁶ Thus gentle braising or cooking steaks to rare or medium-rare best preserves B12 in meat.

Until recently, vegetarian and vegan literature claimed that certain plant foods could provide B12–seaweeds, fermented soybeans (tempeh ), spirulina, even unwashed vegetables that have been fertilized with manure. Proponents of vegetarianism pointed to inhabitants of India, who did not seem to exhibit signs of B12 deficiency in spite of very low levels of animal foods in the diet. Yet as early as 1974, an American study found that 92 percent of vegans, 64 percent of lactovegetarians, 47 percent of lacto-ovovegetarians and 20 percent of semi-vegetarians have blood levels below normal, that is, below the low range that marks the onset of pernicious anemia.⁷

Today, most vegetarian literature does warn about the very real possibility of depletion and recommends routine supplementation with B12. We now know that a source of B12 in the tropical, mostly vegetarian diet in India was insect excrement and parts in stored grains and legumes.⁸ These would have been an unavoidable feature of traditional diets in hot climates until the advent of modern sterilization and storage techniques.
Plant foods said to be sources of B12 actually contain B12 analogs (called cobamides)–substances that block the uptake of true B12 and increase the body’s need for the nutrient.⁹ A surprising source of cobamides is bacterial overgrowth in the small intestines, which can produce B12 analogs.¹⁰ The use of antibiotics, or a diet high in refined carbohydrates, can encourage the proliferation of bacterial overgrowth and lead to B12 deficiencies.

Yet another area for concern is multivitamin products! The late Victor Herbert, a noted B12 researcher, maintains that many multivitamin products contain spurious and even dangerous analogs of B12 possibly formed when crystalline B12 interacts with other nutrients in multivitamin products, such as vitamin C, iron and copper.¹¹

High levels of folic acid can accelerate neuropsychiatric complications in persons with B12 deficiency.¹² Since folic acid intakes of vegetarians tend to be high (from green vegetables and from grain products that have been fortified with folic acid), those following a vegetarian lifestyle may be at increased risk of neurological and psychological problems.

The body stores considerable B12 in the liver. Thus a delay of 5-10 years may separate the beginning of a vegetarian diet (or absorption problems) and the onset of deficiency symptoms. Interestingly, the body can recycle over 75 percent of the B12 it uses.¹³ Used B12 is excreted in bile and then reabsorbed in the small intestine by the same complex process described earlier. Some people have a more efficient recycling system than others and hence can go longer on a vegetarian diet without signs of deficiency. However, more B12 is excreted in the presence of high levels of fiber, a common feature of vegetarian diets.¹⁴

Vegan and vegetarian diets present a real danger for growing children because their stores are very low, especially if their mothers avoided animal foods during pregnancy and lactation. The scientific literature contains numerous case studies describing severe anemia, dramatic growth retardation, irritability and delays in the acquisition of motor skills in B12-deficient children from vegetarian families.

In a recent study, researchers assayed cognitive development in 72 young people raised on diets free of all animal products until at least the age of six and then on a diet containing milk and eggs. When compared with children who had eaten normal mixed diets (including meat) all their lives, they scored substantially lower on tests measuring spatial ability, short-term memory and “fluid intelligence,” that is, the capacity to solve complex problems, abstract thinking ability and the ability to learn.¹⁵

References:

1. Doscherholmen A and others. Proc Soc Exp Biol Med 1975 Sep;149(4):987-90; DoscherholmenA and others. Br J Haematol 1976 Jun;33(2):261-72
2. Tucker KL and others. Am J Clin Nutr 2000;71:514-522
3. www.vegsoc.org/info/b12.html
4. www.slowfood.com/img_sito/riviste/slow/EN/22/crudo.html.
5. Reddy KP and others. J Dairy Sci 1976 Feb;59(2)191-5.
6. Herbert V and Das KC. Folic acid and vitamin B12. In: Shils ME, Olson JA, Shike M, eds. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, Lea & Febiger, 1994:402-25.
7. Dong A and Scott SC. Ann Nutr Metab 1982;26(4):209-16.
8. Nature’s Way 1979;10:20-30.
9. Herbert V. Am J Clin Nutr 1987;46:387-402.
10. Brandt LJ and others. Ann Intern M 1977 Nov;87(5):546-51.
11. Herbert V and Das KC. Folic acid and vitamin B12. In: Shils ME, Olson JA, Shike M, eds. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, Lea & Febiger, 1994:402-25.
12. Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes: Thiamin, riboflavin, niacin, vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline. National Academy Press. Washington, DC 1998; Snow CF. Arch Intern Med 1999;159:1289-98.
13. Herbert V and Das KC. Folic acid and vitamin B12. In: Shils ME, Olson JA, Shike M, eds. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, Lea & Febiger, 1994:402-25.
14. Cullen RW and Oace SM. J Nutr 1978 Apr;108(4):640-7.
15. Louwan MWJ and others. Am J Clin Nutr 2002 Sep;72:762.