= Full article availableFindings from epidemiologic research, that is, observations of large populations, are never as foolproof as conclusions drawn from clinical trials in which there is rigorous control over the study group. But when results involving almost 165,000 people all point in the same direction, you kind of have to take note.
The results—from more than 85,000 women in Harvard’s Nurses’ Health Study, almost 43,000 men in its Health Professionals Follow-Up Study, and some 40,000 women in the Iowa Women’s Health Study—all suggest that people with the highest levels of the mineral magnesium in their diets have the lowest risk for developing diabetes. Katherine Tucker, PhD, director of Tufts’s Dietary Assessment and Epidemiology Research program, says magnesium increases the ability of the body to make use of the hormone insulin, which helps keep blood sugar from rising too high—the hallmark of diabetes. People with the disease tend to have reduced stores of the mineral and lose more than others in urine.
Magnesium intake is not adequate in a large proportion of the population, Dr. Tucker has found in her own research. The Daily Value is 400 milligrams. But, she says, “people eat less than they used to because we eat more and more processed foods, which are stripped of magnesium as well as other nutrients.” Consider that a slice of whole-wheat bread has 24 milligrams of the mineral, while a slice of white bread has only 6. The reason is that when whole grains are refined and made into white flour, certain nutrients are added back, but magnesium is not among them.
Magnesium is found not only in whole-grain foods like bread and cereal. It’s also in other unprocessed items—fruits, vegetables, beans, and nuts. Check out the following table.
Moving Magnesium Back Into the Diet
To consume the recommended 400 milligrams of magnesium, you have to eat an all-around healthful diet; no one food has a large amount of the mineral.
| Food | Magnesium (mg) |
|---|---|
| 1 oz dry roasted almonds | 86 |
| 2 shredded wheat biscuits | 80 |
| 1/2 cup cooked spinach | 78 |
| 1 medium baked potato with skin | 55 |
| 1 cup plain, low-fat yogurt | 43 |
| 1/2 cup cooked brown rice | 42 |
| 1/2 cup vegetarian baked beans | 40 |
| 1 banana | 32 |
| 1 cup skim milk | 28 |
| 3 oz grilled salmon | 28 |
| 1 (1-oz) slice whole-wheat bread | 24 |
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