Determination of vitamin D in relation to body mass index and race in a defined population of black and white women

Abstract

Objective: To examine the contributions of obesity and race to levels of 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) in a defined cohort of black and white women.

Methods: An interventional study was conducted from October 2004 to March 2008, among 219 healthy female volunteers. Serum 25(OH)D and PTH levels were determined in 117 African American women and 102 white women and the results were compared with body mass index (BMI), percentage body fat, serum lipids, and PTH levels.

Results: Black women had lower median levels of 25(OH)D compared with white women (27.3 nmol/L vs 52.4 nmol/L; P<0.001). Serum levels of 25(OH)D below 50 nmol/L were found in 98% of black women and 45% of white women (P<0.001). The differences between the racial groups in the levels of 25(OH)D persisted despite adjustments for body weight, percentage body fat, and BMI. Black women had higher median serum levels of PTH than white women (31.9 pg/mL vs 22.3 pg/mL; P<0.01).

Conclusion: African American women are at significant risk for low vitamin D levels. Studies are needed to determine if low vitamin D status in young African American women is associated with a greater risk for vitamin D-related chronic diseases that can be reduced with vitamin D supplementation.