A study from Oregon State University found that older adults, especially frail ones, with low levels of vitamin D, are at a much greater risk of death than those with higher levels of vitamin D.

For the study, published in the European Journal of Clinical Nutrition, researchers examined data on 4,300 adults older than 60,  from the Third National Health and Nutrition Examination Survey.

They found that adults who had lower levels of vitamin D had a 30 percent increased chance of dying,  and that adults over 60 who were considered frail doubled their risk of death when they had low levels of vitamin D.

About 70 percent of Americans have insufficient levels of vitamin D.  Experts recommend that people consume a balanced diet that includes milk and fish, both good sources of vitamin D and spend time outdoors for natural expose to vitamin D from sunlight (but remember to wear sunscreen!).