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Pfenninger: Considering vegetarian diet
By the Midland Daily News | Posted: Sunday, July 29, 2012 11:15 am
In last week's column, we discussed that there is little doubt that a vegetarian diet is beneficial in many
ways. On the flip side, however, there is concern about whether or not vegetarian diets are deficient in
any particular nutrient. The American Diabetic Association has determined that well-planned vegetarian
diets, including vegan diets, are nutritionally adequate and are appropriate for individuals during all
stages of life. However, some nutrients can be more difficult to obtain with a vegetarian diet, so careful
planning is needed. The use of fortified foods or supplements may be indicated.
Protein
Although often questioned, it appears that vegetarian diets usually exceed protein requirements. Plants
generally are limited in the amounts of amino acids that they contain. (Protein is made up of amino
acids.) However, with a varied diet of legumes, whole beans, nuts and seeds, soy products, and
vegetables, protein needs can be met. Soy protein is almost identical to meat protein.
Vitamin B12
Generally, B12 is found only in animal products, so there is significant concern about deficiency in
vegetarian, especially vegan, diets. B12 levels are generally lower and a true deficiency can take years to
develop. Unless supplemented, there is a real risk of vitamin B12 deficiency in vegetarians. In one study,
52% of vegans and 7% of vegetarians were B12 deficient. Plant foods such as mushrooms, tempeh, miso,
and sea vegetables happen to have B12 but it is an inactive form. Consequently, it is recommended that
B12 be obtained on a regular basis either from fortified foods or supplements. It is especially important
for vegans to obtain supplemental B12 while pregnant or breast feeding. The baby can become deficient
unless the mother consumes enough B12.
Iron
Heme iron, found only in animal foods (meat, poultry, and fish), and non-heme iron, found in eggs and
plant foods, are very different in their absorption potential. Non-heme iron is not well absorbed and is
affected by many other dietary items including vitamin C, tea, coffee, etc. Vegetarian diets can provide
enough non-heme iron but it will need to come from whole grain breads and cereals including fortified
cereals. The key to obtaining enough iron appears to lie in consuming a highly-varied, well-balanced
vegetarian diet. Iron deficiency is not more common in vegetarians, although their iron stores (reserve
iron) are often lower. The amount of iron required is 80% higher in vegetarians because they do not
absorb the non-heme iron as well.
Zinc
The body adjusts and absorbs zinc as it needs it. Nuts, seeds, and whole grains are high in zinc and
consequently there appears to be no concern about deficiency in vegetarians.
Calcium
Medical Procedures Center PC
4800 N Saginaw Rd Midland MI 48640 (989) 631-4545
Copyright 2012 John L Pfenninger MD
A Word from Dr. Pfenninger about:
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There appear to be no significant deficiencies in bone health in lacto-ovo vegetarians. Vegans, however,
do have lower mineral bone densities, although probably not clinically significant. Vegans can obtain
calcium from fortified soy milk and yogurt, tofu, or other plant foods rich in calcium.
Essential fatty acids
Omega-3 fatty acids have proven to be very important in modern-day nutrition. They reduce the risk of
cardiovascular disease but also decrease inflammatory diseases and neurological problems. Fish and
seafood are the main sources of the protective long-chain omega-3 fatty acids. Vegetarian diets include
more of the shorter-chain fatty acids and are generally deficient in the more beneficial ones. Indeed, the
proportions of the long-chain fatty acids in plasma, red cells, breast milk, and tissues are substantially
lower in vegans and vegetarians, compared to omnivores. To optimize their omega-3 fatty acid status,
vegetarians should avoid saturated fats and trans fats. They should increase their intake of short-chain
fatty acids to compensate. These are found in flaxseed oil, walnuts and other nuts from trees, soy
products, and to some extent, in green, leafy vegetables. Omega-3-rich eggs or foods fortified with the
long-chain fatty acids (docosahexaemoic acid - DHA) are another option.
Vitamin D
Vitamin D deficiency is a recently recognized public health problem that involves not just vegetarians.
Vitamin D acts more like a hormone than just a vitamin. Research is difficult because of the variations in
sun exposure, the areas where people live, skin pigmentation, the use of sunscreen, etc. Vitamin D is
found naturally only in a few foods, such as oily fish (cod liver oil), wild mushrooms, and eggs.
However, it has been added to many food products, such as dairy foods. Vegans must rely on the fortified
foods to obtain adequate vitamin D. These days, vitamin D levels are commonly checked and if sun
exposure and the intake of foods fortified with vitamin D are inadequate, vitamin D supplements are
recommended.
Summary
In summary, there have been long-term major concerns about the adequacy of vegetarian diets. It would
seem that a vegetarian diet provides significant advantages over meat-based diets. Vegetarians, in
general, live longer than those who consume meat. However, there are potential deficiencies in some
nutrients, especially vitamin B12, essential fatty acids, and vitamin D. Being aware of these potential
problems should allow vegetarians and vegans to appropriately plan their diets to avoid deficiencies.
Dr. John L. Pfenninger's column appears on Sundays. His office, Medical Procedures Center, is located
in Midland.
Medical Procedures Center PC
4800 N Saginaw Rd Midland MI 48640 (989) 631-4545
Copyright 2012 John L Pfenninger MD