Vitamin D status of black and white Americans and changes in vitamin D metabolites after varied doses of vitamin D supplementation

Abstract

The relation between free and total 25(OH)D did not vary systematically by race in this multiracial population with pre- or well-controlled diabetes. The results need to be replicated in additional cohorts before concluding that the clinical assessment of vitamin D status in blacks and whites should follow a single standard. The CaDDM and DDM2 trials were registered at clinicaltrials.gov as NCT00436475 and NCT01736865, respectively.

Association of free vitamin D3 concentrations and asthma treatment failures in the VIDA Trial

“…However, these results have been questioned owing to technical problems inherent in the VDBP assay used in their studies that led to overestimation of C f and bioavailable concentrations 31–34 . More recent studies have measured C f directly (thereby avoiding issues related to VDBP binding) in patients and reported that C f of vitamin D 3 are generally lower in African Americans depending on physiological or disease state 18,26,35 . For example, directly measured C f were identical in African American and White healthy post menopausal women 18 while in patients with Type 2 Diabetes 35 directly measured C f were lower in African Americans compared to Whites.…”

“…More recent studies have measured C f directly (thereby avoiding issues related to VDBP binding) in patients and reported that C f of vitamin D 3 are generally lower in African Americans depending on physiological or disease state 18,26,35 . For example, directly measured C f were identical in African American and White healthy post menopausal women 18 while in patients with Type 2 Diabetes 35 directly measured C f were lower in African Americans compared to Whites. The results of our study show that C f of vitamin D 3 in African Americans with moderate asthma on ICS are lower compared to Whites at baseline (Table 1).…”

Current Controversies

“…Most studies also find weak but statistically significant inverse relationships between iPTH and free 25(OH)D in normal subjects and prediabetics [39 49 61 65 66]. Areas of uncertainty include relationships between free 25(OH)D and race, birth control pills, pregnancy in the second and third trimester, and biomarkers of vitamin D effects on bone.…”

“…PTH is negatively correlated with free 25(OH)D as well as total 25(OH)D. Serum C-terminal telopeptide of type I collagen has been reported to have a moderate positive correlation with total and free 25(OH)D [67]. With vitamin D supplementation, free 25(OH)D concentrations rise in concert with total 25(OH)D concentrations [[65 67] [64] [68], rising more steeply with D3 supplementation compared to D2 [66]. With high dose D supplementation the changes in iPTH were significantly related to changes in free 25(OH)D but not to changes in total 25(OH)D or changes in total 1,25(OH) 2 D [66].…”

Racial differences in colorectal cancer survival at a safety net hospital

“…Many factors such as obesity, smoking, diets high in fat and red meat, alcohol use, and low vitamin D may contribute [9–12]. We are now understanding that there may be differences in tumor biology between racial groups; Blacks tend to be diagnosed with CRC at a younger age, present with more proximal, advanced, and aggressive tumors, and are more likely to have KRAS mutations [13–18].…”