There is no proof that they work!
There I have said it. It is a fact that many of my patients and friend don't want to hear. However, at this time, there is no clinical randomized, trial results that show any benefit to any of the many supplements that are advertised and written about on the web.
Many of my patients have heard me discuss this with them in the past.
When I was in medical school and starting my residency, there were many patient taking Vitamin C and Vitamin E. Both of these have been shown not to prevent heart disease. (Vitamin E may actually increase the risk of heart disease).
When I was in fellowship, there were many patient taking folic acid (folate) and Vitamin B complexes. Both of these have been shown not to prevent heart disease.
Despite all that has been written about Vitamin D, a recent study has shown that Vitamin D is no linked with heart disease.
Many, many people are using fish oil (Omega-3 fatty acids) to reduce their risk of heart disease. Guess what? A recent study just found no benefit of Omega-3 fatty acids in reducing/preventing heart disease.
Resveratol, a compound found in red wine, gapes and dark chocolate, does increase longevity or reduce the risk of heart disease.
So what can you do? Eat well and exercise.
Studies have consistently shown that staying active and getting lots of exercise and eating a well balanced diet, one high in fresh fruits, vegetables, nuts and beans (Mediterranean Style, DASH, Vegetarian, Vegan) reduces your risk of heart disease.
Therefore, stop supplementing and just start living a healthy, active, well balanced life.