For 20 years, doctors followed 4,497 Americans, aged 18 to 30, who did not have diabetes at the start of the study. Researchers measured magnesium levels in the diet, as well as signs of inflammation and insulin resistance. Compared to those with the lowest levels of magnesium, people with the highest levels were 34 percent less likely to develop diabetes and were much less likely to have inflammation or insulin resistance, two factors that raise chances for many diseases.
In another study, researchers analyzed the diet and lifestyle of 232,007 Americans, aged 50 to 71, who did not have diabetes at the start of the study. After six years of follow-up, doctors found that those who regularly took vitamin C supplements were 9 percent less likely to develop diabetes, and chances were 15 percent lower for those who took calcium, compared to those who did not take these supplements.