A vitamin a day for everyone - maybe; but be careful about all the extras
(April 2004)

The recommendation by an increasing number of experts is a once-a-day multivitamin for every adult. An article in the Journal of the American Medical Association from Harvard Medical School supports that recommendation.

What do we know for sure about vitamins and prevention of chronic diseases, particularly coronary heart and cancer?

The evidence is best for folic acid. Folic acid appears to reduce the risk of coronary heart disease and heart attacks, in part, by controlling blood levels of the amino acid homocysteine, but also possibly by a direct action on the heart. There is still some debate about homocysteine as a risk factor for coronary heart disease and heart attacks, but the evidence is reasonably persuasive for those in the top 10 percent of homocysteine levels. Folic acid, vitamin B6 (pyridoxine), and vitamin B12 can all lower homocysteine levels, but there is no convincing evidence that B6 and B12 add significantly to the homocysteine lowering achieved by a daily intake of 600 to 800 micrograms of folic acid. Folic acid may also reduce the risk of stroke, but that is still unsettled. It is claimed that folic acid reduces the risk of breast cancer in those using alcohol regularly, and the risk of bowel cancer, also particularly in regular alcohol users. The findings in breast cancer are based on an assumption that alcohol use increases to a modest extent the risk of breast cancer; but, that is still debatable and, if it does, it is not clear whether the increased risk is found in regular users of moderate amounts of alcohol or only in heavier drinkers (at least two alcoholic drinks in a day). The data on bowel cancer have many inconsistencies. But, overall, the evidence is clear; a daily intake of at least 400 micrograms is good for your health, and a total intake of 800 micrograms is an even better goal. Every woman of child-bearing age should have a daily intake of at least 400 micrograms, preferably 800 micrograms, to help prevent certain serious neurological problems in the newborn.

Vitamin E has been touted for prevention of coronary heart disease and prostate cancer. The recent evidence on heart disease is very discouraging. At present, there is no justification for urging vitamin E supplementation for the prevention of heart disease. The studies on prostate cancer are inconsistent and contradictory; consequently, no conclusion is possible.

The same is true of beta carotene; at present, there is no reason to recommend beta carotene supplementation for prevention of any disease. The carotenoid lycopene may help control the spread of prostate cancer and might even reduce the risk of developing the disease, but about one-half the studies are supportive, one-half are not. Furthermore, the supportive studies are on lycopenes in the diet (in particular from tomatoes or tomato sauce or paste), so any benefit may be from substances other than the lycopenes in the tomatoes and tomato products. There is no justification for urging lycopenes in dietary supplements.

Vitamin C is a potent antioxidant, but has not been shown to prevent heart disease, stroke, or cancer.
Vitamin D is important in bone strength; a significant percentage of adults have lower than desirable blood levels of vitamin D, reflecting limited dietary sources (the best are fortified milk and cereals, saltwater fish, and fish liver oils) and/or inadequate sun exposure (sunlight allows the manufacture of one form of vitamin D in the skin). Those with inadequate sun exposure (you do not need lengthy exposure, but the sun must reach bare skin) need to be sure about dietary intake. Those not getting enough sun (for example, housebound individuals) who do not have good dietary intake would benefit from a vitamin D supplement.

Supposedly, there is no downside to taking a vitamin supplement, but that may not be entirely true. Supplement entrepreneurs tend to add all sorts of substances, particularly trace elements, such as zinc, copper, selenium, and chromium to the vitamins. In one careful study on bolstering the immune systems of older people by multivitamins, zinc actually interfered with the beneficial effects of the vitamins. In another recent study, taking more than 100 milligrams of zinc regularly doubled the risk for men of developing advanced prostate cancer.

Healthful Life believes the following make sense.

1. All older persons (over age 60) should be on a vitamin supplement that supplies folic acid (400 micrograms), vitamin D (400 international units), and vitamin B12. Older persons do not absorb dietary folates from the intestinal tract as well as younger persons.

2. All women of childbearing age who might become pregnant should take a daily 400 microgram folic acid supplement and include high folate foods in their daily diets.

3. Vegetarians should take a one-a-day B complex vitamin supplement because they may not get enough vitamin B12 and, perhaps, other B complex vitamins.

4. For all other adults, a daily multivitamin is optional. If you do opt for a daily vitamin supplement, Healthful Life recommends one that includes folic acid, the B complex, vitamins D, C, E, and K, and perhaps carotenoids, but that does not contain lots of other ingredients.

For healthy adults ages 20 to 60 (except vegetarians and women who might get pregnant), Healthful Life still favors a healthy diet rather than a multivitamin supplement for two reasons:

- the beneficial effects of foods such as fruits and vegetables may be due to constituents other than their vitamin content or the vitamins contained in the one-a-day vitamin supplements;

- some people may justify unbalanced, poor, or unhealthy diets by assuming the multivitamin protects their health and allows them to ignore a prudent and healthy diet.

Nevertheless, all adults should figure out how much folic acid they are getting in their diets, aim for 800 micrograms and, if necessary, take a daily 400 microgram supplement (either as a specific folic acid supplement or as part of a one-a-day multivitamin).

CLICK HERE for foods high in various vitamins

CLICK HERE for foods high in folates

Fairfield, K.M., Fletcher, R.H. Vitamins for chronic disease prevention in adults. Journal of the American Medical Association. Vol 287 (June 19) Pgs 3116-3129. 2002.