Optimization of Blood Levels of 25(OH)-Vitamin D in African Americans

Two-thirds of the US population, particularly African Americans (AA), is at risk for inadequate or deficient 25-hydroxy-vitamin D (25(OH)VD). Epidemiological studies demonstrate an association between better health outcomes and higher blood levels of 25(OH)VD . Randomized controlled clinical trials have shown that, while supraphysiological high doses of VD are needed to achieve adequate blood levels of 25(OH)VD, not all subjects respond to them. Recent studies have also questioned the therapeutic effects of high-dose VD supplementation. Severe VD deficiency has been associated independently with the future risk of mild cognitive impairment (MCI) and dementia. A reduction in GSH and an increase in the oxidative stress levels of serum, erythrocytes, and circulating lymphocytes has been observed in MCI and Alzheimer disease, findings similar to those in VD deficient persons. Scholarly reviews conclude that excess oxidative stress is one of the major risk factors for AD and support a potential therapeutic role for L-cysteine (LC, a GSH precursor) and vitamin D (VD) supplementation in the treatment of Alzheimer disease symptoms. This application presents the investigators' design for a randomized, double-blind, placebo-controlled clinical trial to test the hypothesis that supplementation with VD in combination with L-cysteine (LC) is more successful at optimizing the statuses of 25(OH)VD [biological signatures] and simultaneously decreasing TNF-α, IR [functional or clinical outcomes], and oxidative stress, suggesting a better therapeutic approach compared with supplementation with VD alone in AA subjects.