Sunny conundrum: Avoiding sunlight lowers skin cancer risk, but also deprives us of vitamin D.

RODALE NEWS, EMMAUS, PA—It seems as though there’s no end to the good deeds of vitamin D: It protects against cancer, diabetes, infections, heart disease—and now hip fractures in older adults, according to a study just published in the Archives of Internal Medicine. Unfortunately, most of us aren’t getting enough of it.

THE DETAILS: In an analysis of 20 previous studies, researchers found that study participants who took more than 400 International Units (IU) of vitamin D per day had about a 20 percent lower risk of fractures at the hip or other nonvertebral site. A separate investigation published in the same issue of Archives revealed that more than 75 percent of Americans are vitamin D deficient, and that blood levels of vitamin D have declined by 20 percent over the last two decades. Increasing awareness about the detriments of sun exposure is the likely reason for that decrease. “Sunlight exposure through ultraviolet radiation is the major source of vitamin D for people, much more so than dietary sources,” says article coauthor Adit Ginde, MD, MPH, assistant professor in the Division of Emergency Medicine at the University of Colorado, Denver. “We do think that the trends we observed can be attributed to people wearing more sunscreen,” he adds; his article notes that SPF 15 lotion can block up to 99 percent of your body’s synthesis of vitamin D.

WHAT IT MEANS: Most of us aren’t getting the D we need. The Institute of Medicine, which sets vitamin-intake recommendations, says that people should get 200 IU/day of vitamin D from birth to age 50, 400 IU/day for adults aged 51 to 70 years, and 600 IU/day for adults 71 years and older. But those levels were set 10 years ago and likely need updating. The results of the bone-health study show, for example, shows that adults age 65 and older should be taking more than 400 IU/day.

Here are a few tips on raising your vitamin D intake and cutting your risks for bone fractures later in life.

• Strive for at least 1,000 IU/day. For adults, Michael F. Holick, MD, PhD, professor of medicine, physiology, and biophysics at Boston University School of Medicine, recommends a 1,000-IU supplement combined with a multivitamin that contains 400 IU more. This combination will help keep your vitamin D levels up throughout the year, especially during the winter, when they tend to drop with the waning daylight. The American Academy of Pediatrics recently raised its recommended levels for kids to 400 IU per day.

• Don’t be too sun-shy. Between April and October (when UVB rays are strongest), spend 10 to 15 minutes outside without sunscreen on, arms and legs exposed, 2 or 3 times a week, says Holick. As soon as those 15 minutes are up, however, slather on the sunscreen. If you’re in a high-risk group for skin cancer (fair-skinned with light hair, for instance), talk to your dermatologist about how much unprotected sun exposure is healthy for you.

• Get fortified. It’s hard to get your recommended vitamin D levels from food, but do consume as many vitamin D–fortified foods as you can, such as milk and fortified bread and cereals.