Featured Nutrient: Magnesium

Long a wallflower in the field of nutrition, magnesium has recently drawn rapt attention. Harvard just released a study of almost 130,000 men and women reporting that those who consumed more magnesium in their diets were less likely to develop type 2 diabetes. Other studies show that it may reduce the risk of coronary heart disease and stroke.

Although crucial to health, magnesium has been sorely neglected by the American diet; some studies suggest that three-quarters of the population fail to get enough. Interestingly, even small increases in dietary magnesium helped lower the chances of diabetes, says researcher Ruy Lopez-Ridaura. Supplements, however, had no effect.

What it does:

Necessary for some of the body's most basic processes, magnesium triggers more than 300 biochemical reactions—most importantly the production of energy from the food we eat. It also generates a response to insulin, the hormone that ushers glucose into the body's cells, where it is used to make energy. It help make proteins in the body, maintains muscle and nerve function, sustains a steady heart rhythm, regulates blood pressure, and keeps bones and teeth strong.

How much you need:

Most Americans take in far less than the RDA of magnesium, says Lopez-Ridaura. "People should try to get around 300 mg/day (women) and 350 mg/day (men) to have an important reduction in their risk of diabetes." But too much supplemental magnesium is also not recommended, the National Nutrition Board has set the upper limit for supplemental magnesium at 350 mg.

Food sources of magnesium:

The mineral is abundant in avocados, nuts and leafy greens. "Magnesium is also very closely associated with fiber and whole grains," Lopez-Ridaura notes. "When grains get processed and refined, they lose a lot of magnesium. Western diets in general are bad for diabetes, and lack of magnesium could be one explanation of this increasing epidemic."

1 cup baked acorn squash = 105 mg

1 oz. toasted wheat germ = 90 mg

1 oz. dry-roasted almonds (24 nuts) = 86 mg

2 rectangular biscuits shredded wheat = 80 mg

1/2 cup cooked spinach = 65 mg

1 stalk broccoli = 59 mg

1 medium kiwi fruit = 23 mg

1/2 medium Hass avocado = 103 mg