Vitamin D Insufficiency Widespread Even in Sunny Climates

Vitamin D is an important fat soluble vitamin that serves several important functions in the body. Unfortunately, inadequate intake leading to an insufficiency or deficiency for this fat-soluble vitamin is quite common. Vitamin D deficiencies occur in all ethnic groups, in all geographic locations and impact all ages- a major concern given the importance of vitamin D in supporting health.

A study published in the American Journal of Clinical Nutrition determined and analyzed blood vitamin D levels in a group of residents of southern Arizona (statistically representative of the larger population).

Participants were categorized into 4 groups on the basis of serum vitamin D concentrations: <10.0 ng/mL, 10.0 to 19.9 ng/mL, 20.0 to 29.9 ng/mL, and 30.0 ng/mL and over. Vitamin D blood levels of 30 ng/ml to 50 ng/ml are considered optimal by most experts.

The average vitamin D concentration for the total population was 26 ng/mL. Of 637 participants, 22.3% had vitamin D concentrations >30 ng/mL, 25.4% had concentrations <20 ng/mL, and 2.0% had concentrations <10 ng/mL. Blacks (55.5%) and Hispanics (37.6%) were more likely to have deficient vitamin D concentrations (<20 ng/mL) than were non-Hispanic whites (22.7%). Exposure to sunlight had a greater effect on vitamin D levels in whites than in blacks and Hispanics.

Adult residents of southern Arizona are commonly deficient in vitamin D despite living in an area with chronic sun exposure. And adults with darker skin were particularly at risk for vitamin D insufficiency in this study.

American Journal of Clinical Nutrition, Vol. 87, No. 3, 608-613, March 2008.