Vitamin D: Winter's Essential Wonder Vitamin
The ABC's of D
You've probably never given vitamin D much thought. Maybe you've assumed that taking a daily multivitamin is all you need to keep your vitamin D bases covered. Or maybe you figured that since many foods -- from milk to bread -- are fortified with vitamin D, you just didn't have to worry about it.
You'd be wrong. Research suggests that we're not getting nearly enough vitamin D -- even the experts are shocked. "An estimated 50 percent of Americans now have a vitamin D deficiency," says Michael F. Holick, MD, PhD, professor of molecular medicine, physiology, and biophysics at Boston University School of Medicine. That's a real concern because low levels of this nutrient can cause bone pain and may lead to depression and heart disease -- even to some cancers.
Doctors are now so worried that they're testing patients' blood for vitamin D in record numbers. One lab, Quest Diagnostics, of Madison, New Jersey, saw an astounding 85 percent jump in blood tests for the nutrient from September 2007 to September 2008, and other labs report similar increases.
Often called the "sunshine vitamin," D is a nutrient that your body produces when exposed to sunlight, and it's essential for helping your bones absorb dietary calcium. Without enough D, bones can soften -- a condition called osteomalacia, which can cause bone pain, muscle weakness, and eventually fractures. Children with low D levels can get rickets, a bone disease that often leads to bow legs and skeletal and dental deformities, among other problems.
But over the past few years there has been an explosion of research that links vitamin D deficiency to an increased risk of such illnesses as breast cancer, heart disease, multiple sclerosis, arthritis, and type 1 diabetes. Lack of D can also weaken your muscles so severely that you have trouble getting out of a chair or walking up a f light of stairs. And it also can cause blue moods, unexplained aches and pains, and fatigue during the winter, says Dr. Holick.
Before D was added to milk, beginning in the 1930s, many American children developed rickets because they didn't get enough of the vitamin. Since then, foods such as cereal, butter and margarine, yogurt and cheese have also been D fortified. As a result, rickets and D deficiency pretty much dropped off doctors' radar -- until this past October, when the American Academy of Pediatrics doubled its recommended amount of the vitamin for babies, children, and teens.
But though doctors are starting to think about D, many don't realize how many conditions a D deficiency can cause. Ellen Teplitz, 54, of Marlborough, Massachusetts, found this out the hard way when her family doctor thought her abnormally high level of parathyroid hormone was a signal that one of her parathyroid glands was malfunctioning. But vitamin D deficiency can also raise parathyroid hormone levels. It turned out Teplitz did not need surgery, as her first doctor suggested, but massive doses of vitamin D to correct a deficiency.
Similarly, women with low bone density should be tested for vitamin D before taking bone-saving drugs or extra calcium, says Susan Haden, MD, an endocrinologist at the Fish Center for Women's Health at Brigham and Women's Hospital, in Boston. "Curing a D deficiency can increase bone density by up to 11 percent," she says.