A flurry of research in the last few years suggests low levels of vitamin D may be partly to blame for much of the ill health of many Americans.

Graduate assistant Mary Heffernan, like many people, probably doesn't get enough vitamin D each day. Along with assistant professor Catherine Peterson of the Department of Nutritional Sciences, she's testing people at MU as part of a study linking vitamin D and inflamatory markers in the blood, which can affect bone health.

"Initially the recommended vitamin D level was set on preventing rickets," Heffernan said.

But new research shows vitamin D goes far beyond better bones.

"Vitamin D has been implicated in the prevention of breast cancer, certain types of auto-immune disease," Peterson said.

It's also proving effective to ward off the flu, diabetes, heart disease and even some neurological disorders. It seems too simple to be true: The average person only needs 10-15 minutes of sunlight a day during the summer to produce the optimum amount of vitamin D. But during winter months and in cooler climates, 1000 IUs of vitamin D3 in a pill will do the trick.

"Who is getting the benefits there? People stuck inside all day or people laying out in the sun?" Heffernan said.

Peterson is using those who don't tan and those who regularly tan for her study, since tanners get the light needed for optimal vitamin D production.

"That's where the tanning salon comes as a benefit," said Beth Mayberry of Tan Rio.

Peterson is still collecting data and needs more tanners to sign up. Heffernan has nothing to worry about because her bones look strong. Although exposure to sunlight is an easy way to get vitamin D, it is also found naturally in fatty fish like salmon and fish liver oils.