Ding... Ding...Musclemom is a winner. Most studies on vitamins are self-reporting, performed on already sick people or a combination of the two. The USDA claims that 60% of Americans are deficient in magnesium and zinc. Based on empirical evidence, a deficiency of the two have an impact on cardiovascular health and testosterone in men. Likewise, I remember a study on smokers that found supplementing 400 IU's of vitamin E had no effect on the rate of lung cancer in smokers....duh! It's an insurance policy, not a cure.