For years, common knowledge has shown that humans need calcium and vitamin D to build strong bones. But a new study by the Institute of Medicine has some people wondering if they're getting enough or too much.
According to new recommendations released Tuesday by the institute's Food and Nutrition Board, most people are getting enough vitamin D through diet and supplements. They also report that there's no proof megadoses will stave off cancer or other illnesses.
"The evidence was inconsistent and inconclusive as to a benefit of vitamin D in preventing cancer, cardiovascular disease, diabetes, autoimmune disorders and many other health outcomes beyond bone health," said Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital in Boston and one of the 14 IOM panel members.
The "sunshine vitamin" and calcium go hand in hand, and both are needed for a lifetime to build and maintain strong bones.
"The question has been how much vitamin D they need to support the calcium in order to get the strongest bones," IOM board member Dr. Stephen Abrams said.
The report concluded infants need 400 units of vitamin D a day and that children and adults need 600 units. That's equivalent to five cups of milk or five ounces of salmon a day - an increase from the old guidelines.
"Have they gone far enough? In my opinion probably not, but it's a step in the right direction," said prominent vitamin D researcher Dr. Michael Holick of Boston University Medical Center.
Some doctors say the new guidelines don't go far enough because the panel based its vitamin D recommendation solely on benefits to bone health and not its ability to reduce the risk some illnesses.
"There is a lot of evidence suggesting that increasing your vitamin D intake will reduce your risk of many serious chronic diseases," Holick said.
"My recommendation is very simple," he continued. "I don't see any downside to increasing your vitamin D intake."
"When I've been recommending for the past decade that people take more than the 200 units, there was a lot of skepticism," he said. "Now they're recommending three times what we recommended in 1997."
The panel also found post-menopausal women may be getting more than the 1,200 milligrams of calcium recommended, while adolescent girls aren't getting enough.