Comparing dietary determinants of serum vitamin D status among African-Americans and Caucasians

摘要

African-Americans (AAs) maintain a high prevalence of vitamin D insufficiency compared to Caucasians. The relationship between dietary sources of vitamin D and serum 25-hydroxyvitamin D (25(OH)D) among AAs remains poorly understood. This research examines the dietary determinants of 25(OH)D levels in AAs and Caucasians, controlling for demographic characteristics. 121 Caucasians and 119 AAs participated in a biomarker based study, comparing the correlation of serum 25(OH) D with dietary sources of vitamin D. Diet was assessed by multiple 24-hour (24-hr) recall and Food Frequency Questionnaire (FFQ). Parallel multiple linear and logistic regression models stratified by race were then used to regress 25(OH)D level and sufficiency (25(OH)D > 20 ng/mL) on major dietary sources of vitamin D—multivitamins (MV), milk, and fish—controlling for age, gender, and BMI. Results show that AAs are sensitive to the method of dietary assessment, with multiple 24 hr recall demonstrating highest correlation (0.4) with 25 (OH)D levels. MV’s association with 25(OH)D levels was highest in both groups, 25% higher in AAs vs. Caucasians (8.6 vs. 6.5 ng/mL per 400 IU). Milk’s impact on serum was similar in both groups but fish was only significant among Caucasians. MV consumption significantly increased odds of vitamin D sufficiency in both groups. Given the high prevalence of vitamin D insufficiency and the strong contribution as compared to milk or fish, MV supplementation is recommended. Additionally, future studies aimed at measuring vitamin D intake should consider the use of multiple 24 hr recall instead of a single measure of FFQ or 24 hr recall since the multiple 24 hr recalls have a stronger correlation to serum 25(OH)D.