Does the High Prevalence of Vitamin D Deficiency in African Americans Contribute to Health Disparities?

Abstract

African Americans have higher incidence of, and mortality from, many health-related problems than European Americans. They also have a 15 to 20-fold higher prevalence of severe vitamin D deficiency. Here we summarize evidence that: (i) this health disparity is partly due to insufficient vitamin D production, caused by melanin in the skin blocking the UVB solar radiation necessary for its synthesis; (ii) the vitamin D insufficiency is exacerbated at high latitudes because of the combination of dark skin color with lower UVB radiation levels; and (iii) the health of individuals with dark skin can be markedly improved by correcting deficiency and achieving an optimal vitamin D status, as could be obtained by supplementation and/or fortification. Moderate-to-strong evidence exists that high 25-hydroxyvitamin D levels and/or vitamin D supplementation reduces risk for many adverse health outcomes including all-cause mortality rate, adverse pregnancy and birth outcomes, cancer, diabetes mellitus, Alzheimer's disease and dementia, multiple sclerosis, acute respiratory tract infections, COVID-19, asthma exacerbations, rickets, and osteomalacia. We suggest that people with low vitamin D status, which would include most people with dark skin living at high latitudes, along with their health care provider, consider taking vitamin D₃ supplements to raise serum 25-hydroxyvitamin D levels to 30 ng/mL (75 nmol/L) or possibly higher.

Keywords: 25-hydroxyvitamin D; African American; European American; Hispanic; UVB; blacks; health disparities; vitamin D; whites.

Figure 1

Average serum 25(OH)D levels (nmol/L) in men and women of African Ancestry ages 25 to 45 years living in four sites [32], and European Americans. The latitudes of the cities are given below the names of the cities. Note: Divide by 2.5 to convert nmol/L to ng/mL.

Figure 2

Prevalence of serum 25(OH)D levels in National Health and Nutrition Examination Survey (NHANES) survey, 2001–2010, by race/ethnicity category among nonusers of vitamin D supplements [35]. Additional calculations courtesy of X. Liu. Note: Divide by 2.5 to convert nmol/L to ng/mL.

Figure 3

Percentage Increase in Cause-Specific Mortality for Black compared to White Americans, Ages 50–64 years—United States, 2015 [150].

Figure 4

Serum 25(OH)D levels and all-cause mortality for elderly Black (n = 1023) and White (n = 1615) men and women followed for up to 8.5 years [159]. Hazard ratios with < 10 ng/mL serum 25(OH)D as the reference were adjusted for other predictors of mortality.