In recent years, vitamin D has been touted as a nutritional superstar.
Beyond its well-known role as a bone builder, studies have suggested that high levels of D, usually achieved by taking supplements, may do everything from reducing chronic pain to preventing the common cold.
At the same time, other reports have found that as many as half of all adults have less than ideal blood levels of D.
That has sent sales of vitamin D blood tests and supplements soaring.
But experts say science doesn’t yet support the use of the high doses that many people may be taking.
Last year, the Institute of Medicine increased the recommended dietary allowance (RDA) of vitamin D for children and adults ages 1-70 to 600 international units (IU), and adults over 70 to 800 IU. But the agency also said many people already get that much from sun exposure and from foods like fish and fortified dairy products.
But the promise of D is so powerful that many policy makers continue to consider emerging evidence.
The latest is the U.S. Preventive Services Task Force, which is set to update its recommendations on vitamin D for cancer and fracture prevention in January. They commissioned one of these two new evidence reviews.