The One Supplement Everyone NeedsFrom SouthBeachDiet.comHere's some surprising news: According to the National Institutes of Health, Americans spend almost $20 billion per year on vitamins and supplements, up a whopping $6 billion since 1999. Even more surprising? Almost all of them have little or no effect on your health. "For years there has been heated debate within the medical community about supplements helping to reduce the risk of certain diseases, but scientific studies have repeatedly failed to support these claims," says Dr. Arthur Agatston, preventive cardiologist and author of The South Beach Diet® and The South Beach Heart Health Revolution.Indeed, research from reputable institutions has shown that most supplements cannot prevent or treat diseases. For example, in one study from the U.S. Preventive Task Force (the leading panel of private-sector experts in prevention and primary care), researchers systematically reviewed the efficacy of vitamins A, C, and E; multivitamins with folic acid; and antioxidant combinations said to prevent cancer and/or cardiovascular disease. Their findings demonstrated that while these vitamins won't harm you, they won't help you, either. Furthermore, the Task Force concluded that there is insufficient evidence to recommend taking supplements containing these nutrients. This research bolsters the outcome of numerous earlier studies, including the groundbreaking Heart Outcomes Prevention Evaluation (HOPE) study, published in the New England Journal of Medicine, January 2000, which found no benefit of vitamin E supplementation in heart-disease patients.Should You Be Taking a Daily Multivitamin?The disappointing results of studies on vitamin supplements and their purported health benefits come as no surprise to Dr. Agatston: "I've been following the scientific evidence closely for many years and have always understood that supplements are not the magic bullet for improving health or preventing disease — eating a good variety of vegetables and fruits, along with healthy fats, such as omega-3s and olive oil, is still the optimal way to get the natural vitamins and nutrients that prevent heart attacks, strokes, cancers, and other chronic diseases."That said, research has shown that one supplement will make a difference: fish oil. Study after study — including the landmark GISSI-Prevention Study, which found that a daily dose of fish oil substantially decreased the risk of sudden death in heart-attack survivors — consistently demonstrates that fish oil helps prevent and treat cardiovascular disease, decreases sudden death from heart attack, and may even stave off Alzheimer's disease.In addition, fish oil, which contains two omega-3 fatty acids, eicosapentaenoic and docosahexaenoic acids (EPA and DHA), has been shown to reduce the inflammation that is a predictor of heart disease — and that's a result which may help avert the risk of deadly heart attacks or strokes. "A certain amount of inflammation in the body is good because it helps blood to clot and wards off infection," explains Dr. Agatston. "But too much inflammation may cause plaque in the arteries to rupture, leading to a blood clot that could cause a heart attack or stroke. To prevent cardiovascular disease and minimize dangerous levels of inflammation in the body, the one supplement that adult men and women should be taking is fish oil."