We recommend that healthy people get adequate nutrients by eating a variety of foods in moderation, rather than by taking supplements. An exception for omega-3 fatty acid supplements is explained below.
The Dietary Recommended Intakes (DRIs) published by the Institute of Medicine are the best available estimates of safe and adequate dietary intakes. Almost any nutrient can be potentially toxic if consumed in large quantities over a long time. Interactions between dietary supplements and prescription drugs and among several dietary supplements taken at the same time may occur. Too much iron can increase the risk of chronic disease, and too much vitamin A can cause birth defects.
There aren’t sufficient data to suggest that healthy people benefit by taking certain vitamin or mineral supplements in excess of the DRIs. While some observational studies have suggested that lower rates of cardiovascular disease and/or lower risk factor levels result in populations who use vitamin or mineral supplements, it isn’t clear if this is due to the supplements. For example, supplement users may be less overweight and more physically active.
Moreover, vitamin or mineral supplements aren’t a substitute for a balanced, nutritious diet that limits excess calories, saturated fat, trans fat, sodium and dietary cholesterol. This dietary approach has been shown to reduce coronary heart disease risk in both healthy people and those with coronary disease.
What about antioxidant vitamins?
Many people are interested in antioxidant vitamins (A, C and E). This is due to suggestions from large observational studies comparing healthy adults consuming large amounts of these vitamins with those who didn’t. However, these observations are subject to bias and don’t prove a cause-and-effect relationship. Scientific evidence does not suggest that consuming antioxidant vitamins can eliminate the need to reduce blood pressure, lower blood cholesterol or stop smoking cigarettes. Clinical trials are under way to find out whether increased vitamin antioxidant intake may have an overall benefit. However, a recent large, placebo-controlled, randomized study failed to show any benefit from vitamin E on heart disease. Although antioxidant supplements are not recommended, antioxidant food sources –especially plant-derived foods such as fruits, vegetables, whole-grain foods and vegetable oils –are recommended.
What about omega-3 fatty acid supplements?
Fish intake has been associated with decreased risk of heart disease. On the basis of available data, the American Heart Association recommends that patients without documented heart disease eat a variety of fish – preferably omega-3-containing fish – at least twice a week. Examples of these types of fish include salmon, herring and trout.
Patients with documented heart disease are advised to consume about 1 gram of EPA + DHA (types of omega-3 fatty acids), preferably from fish, although EPA+DHA supplements could be considered, but consult with a physician first.
For people with high triglycerides (blood fats), 2 to 4 grams of EPA + DHA per day, in the form of capsules and under a physician’s care, are recommended. (See the “Fish Oil and Omega-3 Fatty Acids” entry in this guide for more details.)