Better Health & Living
Make Today D Day
If you don't get enough of this vitamin, you could be facing a steeply increased risk of breast cancer and diabetes
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This one, like many of the scientific studies on vitamin D, had experts buzzing. More than 12,000 Finnish babies who were given what were then considered large doses of vitamin D (2,000 IU) daily until they were a year old had a 78 percent lower risk of developing type 1 diabetes than children who didn’t get a supplement. The remarkable results, published in 2001, became part of a growing body of research that has found that the so-called sunshine vitamin may protect against many diseases, including breast cancer, osteoporosis, and even chronic pain and depression—and that many Americans are seriously D deficient.
Vitamin D is unique among essential nutrients because we get very little of it from food. Instead, our bodies make it when the sun’s ultraviolet rays activate a chemical in our skin that is used to synthesize the nutrient. It’s long been known that D helps our bones absorb calcium, but that turns out to be far from its only critical function. The stunning discovery of vitamin D receptors in almost every tissue and organ suggests that our muscles, nerves, and even our immune systems need D for peak performance.
Not Enough Sun
This news arrives at a time in history when we get less sun exposure than ever before because we’re indoors during prime D-making time (10 a.m. to 3 p.m.), and we slather on sunscreen whenever we’re out. “We have evolved into a species that does not meet its vitamin D needs naturally,” says JoEllen Welsh, PhD, professor of biological sciences at Notre Dame University, who studies vitamin D’s ability to protect against breast cancer.
It’s not surprising, then, that 25 different studies that looked at blood levels of vitamin D in a variety of populations revealed widespread insufficiency. Michael Holick, MD, of Boston University Medical Center cites research showing insufficient levels in 40 to 100 percent of elderly Americans and Europeans, more than 50 percent of postmenopausal women taking osteoporosis medication, 52 percent of Hispanic and African-American adolescents in Boston, and 48 percent of white, preadolescent girls in Maine. When your entire body is clamoring for vitamin D, the tiny recommended amount set a decade ago to prevent rickets (a disease characterized by weak bones) just doesn’t cut it.
“We have evolved into a species that does not meet its vitamin D needs naturally.”
Vitamin D is safe in much higher doses than first thought, too. “There were no controlled safety studies 10 years ago when we set the recommendations, so upper limits were kept pretty low. Now, several good clinical trials show safety at 10,000 IU or more,” says Robert P. Heaney, MD, the Creighton University researcher who helped set the previous standards; he is now among the scientific leaders urging an update.
Proving the benefits of optimal amounts of vitamin D is a bit difficult since the conditions it may prevent, such as diabetes and cancer, develop over many years. But researchers are digging in. According to recent findings, the vitamin can help do the following.
Increase your odds of living longer. Research published recently in Archives of Internal Medicine that combined 18 studies of 57,000 people, mostly middle-aged or elderly, showed those who took any supplemental dose of vitamin D from 300 to 2,000 IU (mostly 400 to 800 IU) were 7 percent less likely to die for any reason over the length of the studies than those who took no supplement. There were no negative side effects from the supplements.
Fend off falls and fractures. Several studies have shown that taking calcium and vitamin D helps the elderly have fewer of the falls and fractures that can lead to prolonged hospitalization and even death. For example, in one study of 389 men and women over age 65 who took 500 milligrams of calcium and 700 IU of vitamin D, fractures decreased by 58 percent. “The jury is in,” says Dr. Heaney. “These supplements definitely reduce fracture risk.”
Increase cancer resistance. Starting around Atlanta, the farther north you go (where year-round sun is weaker), the greater your risk of developing non-Hodgkin’s lymphoma and colon, pancreatic, breast, and prostate cancers. Studies also show that lower blood levels of vitamin D are associated with a 30 to 50 percent increased risk of both getting and dying of colon, prostate, or breast cancer. Though we don’t yet know why, Dr. Welsh’s new research shows that higher levels of vitamin D can prevent, slow, and kill breast cancer cells in lab dishes and animals.
Ease chronic pain. “Young women often have nonspecific bone and muscle pain that is wrongly diagnosed as fibromyalgia,” says Dr. Holick, “and supplementing with vitamin D brings great relief.”
That observation is echoed by W. Michael Hooten, MD, director of the Pain Rehabilitation Center of the Mayo Clinic. There, 25 percent of patients who have had chronic pain for years turn out to be vitamin D deficient. “Vitamin D deficiency doesn’t cause their pain,” he says, “but it does contribute to their discomfort, so I give them supplements to optimize their blood levels.”
Other large studies suggest that vitamin D deficiency puts you at risk for arthritis, multiple sclerosis, type 2 diabetes, depression, and even dental problems.
How to Get Enough
The mounting evidence is so compelling that 15 major vitamin D researchers, including Dr. Heaney, from eight countries recently urged radical changes in dosage recommendations. They now propose that adults get 1,700 IU a day, up from 400 IU, and say that the safe upper limit is 10,000 IU.
“There are only three sources of vitamin D: through sunlight on your skin, which raises your skin cancer risk; diet, which typically delivers only 150 IU a day from fatty fish and fortified milk, orange juice, and cereal; and supplements,” says Martin Weinstock, MD, chairman of the American Cancer Society’s Skin Cancer Advisory Group. “All the experts agree that for pennies a day, you can add a safe vitamin D supplement that will boost your blood to optimal levels.”
In fact, all of the experts we interviewed agreed that a supplement of 800 to 1,000 IU is safe for everyone except those with a rare absorption disorder. People with dark skin (which slows sun absorption), those who are indoors from 10 a.m. to 3 p.m. most of the year or live north of Atlanta, and those who are obese (vitamin D hides in body fat instead of circulating in blood) are most at risk of D deficiency. “Ask your doctor about a blood test, or just take a supplement,” says Dr. Heaney. The odds are, the boost will be good for your health.
Most experts also recommend that you don’t completely shun the sun. They particularly advise fair-skinned people who live in Northern states to aim for 10 to 15 minutes of sun exposure on their arms and legs two or three times a week when the sun’s out. Use SPF 15 sunscreen on your face, but leave your limbs unprotected.
Maryland-based freelancer Colleen Pierre, RD, is an award-winning nutrition writer.
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