You’d have to be living in a cave—and therefore vitamin D deficient—to have missed the nonstop news about this remarkable nutrient. Why all the attention? Two reasons: widespread alarm when doctors realized that a huge number of Americans had low vitamin D levels and a concurrent (and continuing) surge in research.

Other than fatty fish and some mushrooms, foods don’t offer a good dietary source of vitamin D. The best source of the “sunshine vitamin” is your own body, but to make it count you must spend 10 to 15 minutes in the sun at least three times per week with your bare, unsunscreened skin largely exposed—which most people don’t do. “The incidence of vitamin D deficiency is due almost entirely to changes in lifestyle,” says Robert P. Heaney, MD, of Creighton University in Omaha, Nebraska. “Our grandparents spent more time outdoors; kids used to play outside. Nearly everyone spent a lot of time outdoors, without sunscreen. These changes in our society have crept up on us.” In this new reality, supplements become a helpful and even imperative approach.

Thanks to increased awareness of its health benefits, vitamin D is evolving from a “winter” vitamin (when your body makes less because the sun is low on the horizon) to a year-round supplement. There are two forms: D2, produced from fungus, and D3, derived from sheep lanolin or fish oil. Though not suitable for vegetarians, D3 is the type your body makes and is far better absorbed than D2 (some research suggests D2 actually lowers D3 levels in the body). Here’s why D is a must in your health arsenal.

Longer life

Because vitamin D plays so many different roles in the body, a deficiency can boost the risk of dying sooner rather than later. A European study of more than 26,000 middle-age and elderly men and women determined that low vitamin D levels correlated to 57 percent greater risk of dying from any cause, including cardiovascular diseases, over periods ranging from 4 to 16 years.

Reduced cancer risk 

More than 60 studies have tied adequate vitamin D levels to a lower risk of various cancers, including those of the breast, prostate, colon, and lung, as well as leukemia and myeloma. But the vitamin really shines when it comes to improving the survival of cancer patients, especially those diagnosed with lymphoma, colorectal cancer, and breast cancer. New studies report a 42 percent to
50 percent lower risk of death from breast cancer when women maintained relatively high vitamin D levels.

Pain relief

In a 2014 study, researchers discovered that supplemental vitamin D can ease widespread pain. In another study of 60 Norwegian men and women with chronic pain, including fibromyalgia, researchers found one-fourth were deficient in the vitamin. After three weeks of regular sun exposure, participants’ vitamin D levels rose and they benefited from an average 60 percent decrease in pain. Several previous studies have found that vitamin D supplements reduce low-back pain.

Blood sugar management

A respectable body of research indicates that vitamin D, sometimes in combination with calcium, can prevent or control prediabetes and type 2 diabetes. Both nutrients aid insulin function and glucose regulation. A new study conducted at the University of Massachusetts Medical School found that taking vitamin D supplements for 8 to 16 weeks reduced blood sugar levels by 10 percent. In separate research, vitamin D supplements significantly lowered blood sugar levels and improved insulin resistance in women with gestational diabetes.

Bone and muscle strength 

You need vitamin D to make muscle and to get calcium into bone. Researchers in Scotland reported that taking 1,000 IU of vitamin D daily helped older women maintain bone density, while smaller amounts (400 IU) or placebos did not. And in a 2013 study in Osteoporosis International, a combination of vitamin D and calcium intake reduced the risk of hip fractures by 20 percent in women.

Remember: It’s a good idea to talk to your health care provider before starting a new supplement.