A new study supports the idea that correcting inadequate blood levels of vitamin D is more important than increasing dietary calcium to improve bone health and reduce fractures.

Researchers analyzed the vitamin D levels in about 10,000 men and women aged 20 and older. They found that a large fraction of younger and older adults were below a suggested desirable level of vitamin D concentration in the blood.

They say their findings underscore the importance of vitamin D and its ability to help the body utilize calcium. In addition, researchers say the study may also explain why increasing calcium alone isn’t always successful in dealing with loss of bone density.

The body needs adequate dietary calcium to reach its full potential in terms of bone mass. Other factors that affect bone mass include exercise, smoking and vitamin D, which is necessary for calcium absorption.

The average recommendation is 600 IUs of vitamin D daily. It can be found in food sources like milk, tuna, eggs and fortified breakfast cereals as well as in nutritional supplement form. Exposure to sunlight can also boost vitamin D levels.