Alexander C. Chester, MD

The standard authorities state that for most healthy adults consuming a well-balanced diet, multivitamins (which usually contain 50%-150% of the recommended adult daily requirement of the standard vitamins) are not needed. However, some evidence suggests that taking a daily multivitamin causes a small decrease in cancer risk.

All authorities agree that there are important areas where extra vitamins are needed:

It is very important for women who might become pregnant to take a supplemental dose of 400 mcg of folic acid daily. The extra folic acid insures against inadequate reserves and prevents neural tube defects in the newborn such as spinal bifida.

A multivitamin is important for individuals with malabsorption (such as celiac disease, gluten-sensitivity), a vegan diet, alcoholism and certain other chronic conditions.

For other adults folic acid supplementation is unnecessary and perhaps unwise. An increased level of folic acid can mask vitamin B₁₂ deficiency, a very serious deficiency problem, and may stimulate the growth of some cancers.

In order to prevent osteoporosis and decrease the risk of falls (a curious, but substantiated association) adults need a minimum of 800 units of vitamin D daily, taken either through dietary sources or as a supplement. Unlike all other vitamins, vitamin D can be produced by humans internally. In this case sunlight is needed, and exposure is often insufficient.

Dietary sources of vitamin D include milk, yogurt and soy milk—all of which are usually fortified with vitamin D. Salmon, sardines, tuna and cheese are other good sources of vitamin D.

Since vitamin D levels are often low in adults and since vitamin D deficiency causes bone problems and has been possibly linked to other diseases, taking 600-800 units daily, particularly in older adults, seems prudent.

Vitamin A levels are usually normal in the industrialized world and supplementation is not needed and, indeed, may be harmful. Excessive doses in pregnant women can cause abnormalities in the newborn. Additionally, in all adults excessive doses can cause osteoporosis as well as possibly increasing the risk of cancer and cardiovascular disease.

Likewise, vitamin E levels are usually adequate and high dose vitamin E (more than 400 units daily) supplementation is unwarranted since excessive vitamin E levels are associated with increased all-cause mortality.

Vitamin C supplementation is safe, but has no proven benefit.

Older persons should consider taking a B₁₂ supplement since levels of this very important vitamin can drop with age. Liver, fish, beef, cheese and eggs are dietary sources of vitamin B₁₂. A vegan diet eliminates many dietary sources, making supplementation necessary.

Filed under: Anemia, Cancer, Cardiovascular, Chronic Fatigue, Conditions, Vitamins and Supplements |