More patients are getting tested for vitamin D deficiency, but the value of the tests remains too murky to make them routine, an influential advisory group says.

There simply isn't enough evidence that testing the blood of healthy, symptom-free people for vitamin D deficiency will end up improving people's health, says the draft recommendation from the U.S. Preventive Services Task Force. The task force — an independent panel whose recommendations influence which prevention measures are widely adopted — also says there's little evidence testing would hurt.

Low vitamin D levels have been linked with bone fractures, falls, cancer, diabetes, heart disease, depression and even early death, the task force says. But studies have not shown that giving vitamin D supplements to apparently healthy people with low levels can prevent those problems.

Another issue: Expert groups disagree on how low is too low. Also, different lab tests can produce different results. Because of varying standards and study methods, estimates of vitamin D deficiency in the U.S. population range from 19% to 77%, the task force says.

"There's a lot of controversy here," says task force co-chair Albert Siu, a geriatrics professor at the Icahn School of Medicine at Mount Sinai in New York.

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