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CAN FRUITS, VEGETABLES, AND VITAMINS PREVENT STROKE AND HEART ATTACK?

(March 2002)

The answer is maybe. In 1997, a very good review appeared in the International Journal of Epidemiology.Nothing since then has appeared in the literature that changes the conclusions.

For stroke resulting from reduced blood supply to the brain, the evidence of a protective effect is reasonably good for at least four to five servings a day of fruits and vegetables; but, it is not clear which fruits and vegetables are most effective. There is no persuasive evidence vitamin C or Beta carotene is beneficial, no adequate evidence on folic acid, and inconsistent evidence for vitamin E. One recent study suggested that vitamin E from food reduces stroke risk, whereas another study argues vitamin E from supplements, but not from foods is moderately protective.

At present, eating four, five, or more portions of fruits and vegetables a day probably results in a modest reduction in risk of stroke. No specific vitamin can be recommended.

What about coronary heart disease and heart attacks? Here the evidence is not as strong. About one-half the studies on fruits and vegetables show reduction in risk, one-half do not. Although there is some evidence that vitamin E is beneficial, there is increasing doubt whether vitamin E from foods (low dose) or from supplements (higher dose - over 100 milligrams per day) really reduces risk of heart attack. Some studies suggest that lower blood levels or lower intake of folic acid increases coronary heart disease and heart attack risk; in contrast, high daily intake (over 400 micrograms) of folic acid reduces risk. But, we do not have enough studies and no studies yet of giving folic acid and seeing if that reduces the risk of coronary heart disease and heart attacks. There is, at present, no persuasive evidence that either vitamin C or Beta carotene in foods or supplements protects against coronary heart disease or heart attacks.

Eating four or five servings of fruits and vegetables appears to clearly offer some protection against some cancers and probably against stroke due to reduced blood supply to the brain. For coronary heart disease and heart attack, the evidence is weaker and the operative word is may. The evidence for folic acid protecting against heart attack is improving. Folic acid may act by lowering homocysteine levels (a risk factor for coronary heart disease), as well as by other mechanisms. On the other hand, support for vitamin E as protection against coronary heart disease and heart attacks is waning as new studies appear.

Remember, for stroke prevention:

• Keep your blood pressure in the normal range, if possible in the lower part of the normal range.

• Do not smoke.

• Try to avoid abdominal obesity (a big gut).

• Also, eating plenty of fruits and vegetables is a reasonable idea.

For protection from heart attacks, the fully-documented major actions are:

• Keep your blood pressure in the normal range, preferably in the lower part of the normal range.

• Do not smoke.

• Keep your blood cholesterol level below 200 milligrams. If you are over age 65, some experts stick with 200 milligrams as the upper limit of acceptable; others say up to 210 milligrams or even 220 - but no higher. After age 75, the dangers of a high cholesterol, at least up to 240 milligrams, is uncertain.

• Try not to gain too much weight; more than 20 percent above ideal weight is, by itself, a risk factor for heart attack.

• Do not be sedentary - get at least some exercise.

Dietary-vitamin prescriptions that might help in protecting against heart attack are:

• Folic acid, at least 400 micrograms a day. If over age 60, you should get the 400 micrograms either through fortified foods or supplements. Other younger adults can get the 400 micrograms of folate a day by foods, fortified foods, or supplements. Some people need 800 micrograms of folic acid (by a combination of diet and supplement) to significantly reduce homocysteine levels.

• Include plenty of whole grains in the diet - at least five to six servings a week.

• Eat oily fish at least one or two times a week (click here for list of oily fish).

• Include four or more servings of fruits and vegetables a day in your diet.