Vitamin D
This vitamin's biggest claim to fame is its role in strengthening your skeleton. But vitamin D isn't a one-trick nutrient: A study in Circulation found that people deficient in D were up to 80 percent more likely to suffer a heart attack or stroke. The reason? D may reduce inflammation in your arteries.
Mens Health: Vitamin D is created in your body when the sun's ultraviolet B rays penetrate your skin. Problem is, the vitamin D you stockpile during sunnier months is often depleted by winter, especially if you live in the northern half of the United States, where UVB rays are less intense from November through February.
Magnesium
This lightweight mineral is a tireless multitasker: It's involved in more than 300 bodily processes. Plus, a study in the Journal of the American College of Nutrition found that low levels of magnesium may increase your blood levels of C-reactive protein, a key marker of heart disease.
Mens Health: Nutrition surveys reveal that men consume only about 80 percent of the recommended 400 milligrams (mg) of magnesium a day. "We're just barely getting by," says Dana King, M.D., a professor of family medicine at the Medical University of South Carolina. "Without enough magnesium, every cell in your body has to struggle to generate energy."
Vitamin B12
Consider B12 the guardian in men's-health: In a British study, older people with the lowest levels of B12 lost brain volume at a faster rate over a span of 5 years than those with the highest levels.
Mens Health: Even though most men do consume the daily quota of 2.4 micrograms, the stats don't tell the whole story. "We're seeing an increase in B12 deficiencies due to interactions with medications," says Katherine Tucker, Ph.D., director of a USDA program at Tufts University. The culprits: acid-blocking drugs, such as Prilosec, and the diabetes medication metformin.