It could be the simplest way to slash your diabetes risk: Add a serving or two of magnesium-rich beans and greens to your meals.

Magnesium has long been linked to diabetes prevention--and a new study confirms it. Researchers have found that those who get their share of this crucial mineral have a dramatically lower risk of the disease.

Too bad most of us aren't getting our share... but more on that in a moment.

Researchers tracked 4,497 men and women between the ages of 18 and 30 years old at the start of the study for 20 years, and found that those who got 200 milligrams of magnesium for every 1,000 calories consumed were 47 percent less likely to become diabetic than those who took in just 100 milligrams of the mineral for every 1,000 calories consumed.

Since only 330 of the subjects--slightly more than 7 percent--developed diabetes, it might be easy to chalk this up to a statistical fluke.

Easy... but wrong, because the benefits went far beyond the numbers. The researchers found that those with the higher levels of magnesium had lower levels of insulin resistance and inflammation markers, according to the study in Diabetes Care.

And, as I mentioned, other studies have also established a clear link between the mineral and disease protection. One study even found that higher levels of magnesium lowered diabetes risk across all age groups and in both genders.

But unless you're eating a steady diet of magnesium-rich foods or taking a supplement, odds are you don't have enough.

By some estimates, between 50 and 70 percent of all U.S. adults get less than the recommended daily allowance of between 300 and 400 milligrams per day... with some getting barely 20 percent of what they really need.

And that's a huge mistake... because in addition to beating back diabetes, magnesium can also help bring your blood pressure down to healthy levels and reduce your stroke risk. Magnesium is also essential to bone health, muscle strength, immune system function and more.

In fact, magnesium is a catalyst for more than 300 biochemical reactions in the body that we know of--and probably many more that we don't.

The best sources of magnesium include nuts, grains, beans and greens--especially spinach. And if you don't get enough from your food, magnesium supplements cost just a few bucks a bottle.

It could turn out to be the best investment you'll ever make--just be sure to pair it with a healthy diet, because no mineral in the world will protect you from the ravages of snacks, fast food and frozen dinners.