Possible role of serum 25-hydroxyvitamin D in black-white health disparities in the United States.

Significant health disparities exist between African Americans (AAs) and White Americans (WAs). The all-cause mortality rate for AAs in 2006 was 26% higher than for non-Hispanic WAs. Explanations for the disparities usually include socioeconomic status, lifestyle behaviors, social environment, and access to preventive health care services. However, several studies indicate that these factors do not account for the observed disparities. Many studies report that vitamin D has important health benefits through paracrine and autocrine mechanisms and that higher serum 25-hydroxyvitamin D (25[OH]D) levels are associated with better health outcomes. AAs have a population mean serum 25(OH)D level of 16 ng/mL, whereas WAs have a level of 26 ng/mL. From preliminary meta-analyses of serum 25(OH)D level-disease outcome from observational studies, differences in serum 25(OH)D level for AAs and WAs can explain many of the health disparities. The ratios of mortality rates for AAs to WAs for female breast cancer, colorectal cancer, cardiovascular disease, and all-cause mortality rate in 2006 were 1.34, 1.43, 1.29, and 1.26, respectively. The 25(OH)D level-disease outcome ratios for 16 ng/mL versus 26 ng/mL for the same diseases were 1.26, 1.44, 1.27, and 1.26, respectively. The close agreement between these 2 sets of numbers suggests that low serum 25(OH)D level is an important health risk for AAs. Given the widespread vitamin D deficiency in the AA population and the potential widespread health benefits that accompany adequate replacement, we believe that addressing this issue may be the single most important public health measure that can be undertaken.