The study was the work of researchers at the University of Colorado Denver School of Medicine. They collected data on vitamin D levels in 18,883 people collected between 1988 and 1944, and 13,369 people collected between 2001 and 2004. The data were from the Third National Health and Nutrition Examination Survey.

 

Optimal levels of the vitamin range from 30 nanograms per milliliter to 40 nanograms per milliliter. The Institute of Medicine recommends 200 units daily of vitamin D in children and adults up to age 50, and 400 to 600 units for older adults. However, these quantities are far below, according to some doctors who recommend supplements as well.

 

The researchers found that average vitamin D levels were 30 nanograms per milliliter from 1988 to 1994, but decreased to 24 nanograms per milliliter between 2001 and 2004. In addition to that, vitamin D levels of less than 10 nanograms per milliliter increased from 2 percent to 6 percent over the follow-up period. Fewer people than ever had vitamin D levels of 30 nanograms per milliliter or higher.

 

“Increases in vitamin D deficiency in the population may have reduced the overall health of the population. Since sunlight is the body's major source of vitamin D, increases in sunscreen, sun avoidance, and overall decreased outdoor activity, while successful in reducing skin cancers, has probably reduced vitamin D levels in the population,” said lead researcher Dr. Adit Ginde, an assistant professor of surgery at the University of Colorado Denver School of Medicine.

 

Vitamin D helps the body metabolize calcium playing a central role in bone formation. Recently, studies have linked vitamin D deficiency to a series of diseases including cancer, high blood pressure, multiple sclerosis, autoimmune diseases, diabetes, and diseases of the nervous system.