Do you know how magnesium affects your risk of diabetes?

People know that they may be able to lower their risk of type 2 diabetes by losing excess weight and eating less sugar. But few know that getting enough magnesium may also ward off the disease.

“In one observational study after another, we see that a higher magnesium intake is associated with a lower incidence of type 2 diabetes,” says Adela Hruby, a research fellow at the Harvard School of Public Health.

For example, when Hruby and her colleagues followed roughly 2,500 participants in the Framingham Heart Study for seven years, those who consumed the most magnesium (around 400 milligrams a day) had about half the risk of type 2 diabetes of those who consumed the least (around 240 mg).

“We looked at people who were initially healthy and also at people who were prediabetic, so they were at higher risk,” explains Hruby. “Magnesium appeared to be particularly beneficial for those with higher than normal blood sugar when they entered the study.”

And it’s not just Framingham. After looking at  13 studies on more than 536,000 people, researchers estimated that the risk of diabetes was  14 percent lower for every  100 mg of magnesium the people consumed.

But something else about people who eat more magnesium could explain why they have a lower risk of diabetes. So scientists do trials to see if giving people magnesium lowers their blood sugar or insulin.

“In some studies on people who have either metabolic syndrome or prediabetes, magnesium lowers fasting blood glucose or insulin or HbA1c,” notes Hruby. (Hemoglobin A1c is a long-term measure of blood sugar levels.)

But not all studies agree. What’s more, “there haven’t been sufficient numbers of trials in humans,” says Hruby. “That is really the bottom line.”

Soup with Beans and Greens

How might magnesium help prevent diabetes?

“It might help beta-cells in the pancreas secrete insulin,” says Hruby. “And it may also make cells more sensitive to insulin, so that your muscles and other tissues respond better to it.”

Millions of people get less magnesium than experts recommend.

“Fifty percent of the country is under-consuming magnesium,” notes Hruby. But that doesn’t mean they’re deficient. “We don’t have great data on magnesium levels in the body,” she adds. Fortunately, most magnesium-rich foods are healthy. And a growing body of evidence suggests that people who get more magnesium have a lower risk of stroke and heart disease, as well as diabetes.

“Magnesium is at the heart of the chlorophyll molecule, so every leafy green has it,” explains Hruby. “Whole grains and beans are also good sources. My favorite sources happen to be chocolate and coffee.” In fact, an 8 oz. cup of coffee has only 7 mg. But a  1 oz. shot of espresso, which is more concentrated, has 24 mg. (Cappuccinos, lattes, mochas, and macchiatos are typically made with espresso.)

Magnesium pills are not a good substitute

Taking a magnesium supplement does have a drawback: more than 350 mg a day from pills may cause diarrhea. That’s not a problem with the magnesium in foods. “You can’t get too much magnesium from foods,” adds Hruby.

Another reason to get your magnesium from foods: If it’s not magnesium but something else in beans, leafy greens, whole grains, and coffee that protects your health, you won’t get it from a pill.

Sources: Diab. Care 37: 419, 2014; Diab. Care 34: 2116, 2011; Diab. Med. 23: 1050, 2006; Int. J. Cardiol. 196: 108, 2015; J. Am. Heart Assoc. 2: e000114, 2013.


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