Demographic, lifestyle, and genetic determinants of circulating concentrations of 25-hydroxyvitamin D and vitamin D–binding protein in African American and European American women,

Abstract

Vitamin D may have anticancer activities. The high prevalence of vitamin D deficiency in African Americans (AAs) may be a contributing factor to the cancer health disparities between AAs and European Americans (EAs). We compared concentrations of 25(OH)D and vitamin D-binding protein (VDBP) in AA and EA women and investigated determinants of the vitamin D-biomarker concentrations in both populations. We used data and biospecimens from 909 AA and 847 EA healthy control subjects from the Carolina Breast Cancer Study (CBCS) and the Women's Circle of Health Study (WCHS) in the African American Breast Cancer Epidemiology and Risk Consortium. We measured plasma 25(OH)D and VDBP concentrations in all participants and genotyped 67 vitamin D-related genes in AA women only. AA women had lower 25(OH)D concentrations than did EA women (mean ± SD: 14.2 ± 8.1 compared with 21.1 ± 11.5 ng/mL, respectively; < 0.0001) but similar concentrations of VDBP (mean ± SD: 344 ± 133 compared with 336 ± 124 μg/mL, respectively; = 0.25). With VDBP and other factors controlled for, the observed racial difference in 25(OH)D concentrations did not diminish. Relations of demographic and lifestyle factors with 25(OH)D were similar between AA and EA women. Although none of the genetic variants that have been identified in previous genome-wide association studies of 25(OH)D concentrations in EAs were significant ( > 0.05) in AAs, AA women who carried the allele of a functional single nucleotide polymorphism rs4988235, which has been previously associated with lactase expression and lactose tolerance, had higher dietary vitamin D intake and higher measured 25(OH)D concentrations. AA women have lower concentrations of total 25(OH)D than EA women do, but both groups have similar VDBP concentrations, suggesting that there are lower concentrations of free 25(OH)D in AAs. Although demographic and lifestyle determinants of 25(OH)D concentrations are similar between the 2 groups, genetic determinants may be ethnicity specific. Larger studies in AAs will be needed to fully elucidate the underlying determinants of low vitamin D concentrations in AA populations.

Patterns of Vitamin D, Parathyroid Hormone and c-Terminal Telopeptide of Collagen Type 1 in Caucasian and African Descent HIV-Infected Populations in Central Europe

“…In this cohort of 889 HIV infected patients, in which we excluded major potential confounders on the variables of interest (impaired kidney function, use of anti-resorptive therapy, calcimimetics, and vitamin D supplementation) with either Caucasian or African ethnicity, we found that traditional risk factors of low bone mineral density – low vitamin D, low calcium and, higher PTH levels with a higher frequency of (consecutive) secondary hyperparathyroidism – were more common in the African descent population, which is in good concordance with data from general African American populations in North America. 8-10 An exploratory, visual analysis also supported the assumption of different relations between vitamin D, PTH, and β-CTX (Figures 1-3) in the two ethnic groups. The most distinct difference seems to be found in the relation between vitamin D and PTH which will be discussed below.…”

Cancer in Population of African Ancestry: A Review

“…Studies on demographic, lifestyle, and genetic determinants of circulating concentrations of 25-hydroxyvitamin D [25(OH)DJ and vitamin D-binding protein (VDBP) in African American and European American women suggested that African American women have lower concentrations of total 25(OH)D than European American women do, but both groups have similar VDBP concentrations. The study suggested that there are lower concentrations of free 25(OH) D in African Americans [34]. Prostate cancer incidence and mortality rates vary widely among populations, with the highest documented rates among American and Caribbean men of African descent [35].…”

The role of vitamin D in perinatology. An up-to-date review

“…Factors influencing lower photon absorption (thus reducing the conversion of vitamin D to the skin) are older age, sunscreens, low sun exposure, geographical latitude, winter season, and increased skin pigmentation [23]. The latter factor is particularly important for African Americans, in which skin melanin content is much higher than that of other races [24,25].…”