Vitamin D, sunlight exposure, and bone density in elderly African American females of low socioeconomic status

Abstract

Background and objectives: Darker skin pigmentation and aging are known factors influencing the body's ability to synthesize adequate amounts of vitamin D (25OHD). The objective of this study is to determine the 25OHD insufficiency in elderly African American females of low socioeconomic status (SES) in a southern latitude during springtime sun exposure.

Methods: Patients >or= 70 years old who did not have disorders that might affect vitamin D and calcium absorption/metabolism were enrolled at a community health center. Serum calcium, 25OHD, and intact parathyroid hormone were measured and repeated 6--8 weeks later. Bone mineral density (BMD) scan results were obtained from clinic records.

Results: Most subjects (86.4%) had inadequate 25OHD levels < 32ng/mL, and no clinically significant rise in levels was seen after 6--8 weeks of sun exposure. A quarter of subjects had truly deficient 25OHD levels <or= 15ng/mL. 25OHD levels were positively correlated with BMD only at the lumbar spine. Fifty-two percent of subjects were osteopenic, and 9% were osteoporotic.

Conclusions: 25OHD insufficiency is common among low SES elderly African American women, and springtime sunlight exposure does not cause significant increases in 25OHD. Additionally, this population has low calcium and vitamin D intake from diet, and more women than expected had reduced BMD.