The U.S. Preventative Services Task Force cautions healthy postmenopausal women against taking daily low quantities of vitamin D and calcium to prevent bone fractures, citing a lack of evidence by which doses of the supplements can be calibrated as either advantageous or detrimental.
In its report released earlier today, the panel also deemed research conducted on behalf of vitamin D as a possible preventative agent against cancer insufficient. Previous studies have identified an inverse relationship between vitamin D and various types of cancer, in which heightened levels of the vitamin decreased risk for contraction of the disease. Such reports were regarded by the government advisory panel as mixed and thus, inconclusive.
"Many people take the supplements, but the science was insufficient to make recommendations for everyone,” said Timothy Wilt, the lead author of the panel report.
Both calcium and vitamin D have long been regarded by experts as the top nutrient candidates for better bone health, and in the case of vitamin D, better muscle health as well. The Institute of Medicine endorses a daily intake of 600-800 international units (IUs) of vitamin D and 700-1,300 milligrams of calcium, contingent with age. The task force considered doses less than or equal to 400 IU of vitamin D and 1,000 milligrams of calcium for fracture prevention; what it found instead was an increased risk for kidney stones in patients and, therefore, sanctioned against the use of the nutrients as fractural deterrents.
The rulings have come at a time when uncertainty surrounding the health benefits of vitamin D and calcium supplements is particularly elevated. Given the panel’s history of sometimes questionable advice — it recommended against prostate-specific antigen tests to screen for prostate cancer in healthy men and counseled women in the 50 to 74 age bracket to have a mammogram every other year instead of annually — some medical professionals remain skeptical.
"It's a more complex picture than they're painting," says Jen Sacheck, an assistant professor and researcher in the antioxidants research laboratory at Tufts University in Boston. "If you live in New England there are many months of the year when you're not getting adequate amounts of vitamin D from the sun. I check blood levels of young and older people and find them to be low in New England."
Like Sacheck, the spokesman for the Society of Bone and Mineral Research, Clifford Rosen, is not convinced that the panel’s findings are valid either. Rosen mentioned the task force’s disregard of a study conducted by the Women’s Health Initiative in which supplements provided a 10-11 percent reduced risk of fractures for 36,282 women. The study also found that postmenopausal women afforded the supplements saw improvement in their bone density.
Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York and an American Heart Association spokeswoman, agrees with the task force’s assumption that calcium cannot prevent cancer and fractures, but emphasizes with consumers, who will no doubt be exasperated over the competing recommendations.
"To tell people, 'Take calcium and vitamin D to prevent fractures as you get older,' that's not panning out anymore," she says. "Even if you are at risk for a fracture, maybe you have to try other lifestyle changes, like diet and weight-bearing exercise."
For now, a balanced diet and a consistent level of fitness is the best advice to adhere to, she added.