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Effects of Genetic and Nongenetic Factors on Total and Bioavailable 25(OH)D Responses to Vitamin D Supplementation

2016; Oxford University Press; Volume: 102; Issue: 1 Linguagem: Inglês

10.1210/jc.2016-2930

1945-7197

Pang Yao, Liang Sun, Ling Lu, Hong Ding, Xiafei Chen, Lixin Tang, Xinming Xu, Gang Liu, Yao Hu, Yiwei Ma, Feijie Wang, Qianlu Jin, Zheng He, Huiyong Yin, Rong Zeng, Yan Chen, Frank B. Hu, Huaixing Li, Xu Lin,

Diet and metabolism studies

Abstract Context: Little is known about how genetic and nongenetic factors modify responses of vitamin D supplementation in nonwhite populations. Objective: To investigate factors modifying 25-hydroxyvitamin D [25(OH)D] and bioavailable 25(OH)D [25(OH)DBio] responses after vitamin D3 supplementation. Design, Setting, Participants, and Intervention: In this 20-week, randomized, double-blinded, placebo-controlled trial, 448 Chinese with vitamin D deficiency received 2000 IU/d vitamin D3 or placebo. Main Outcome Measures: Serum 25(OH)D, vitamin D-binding protein (VDBP), parathyroid hormone (PTH) and calcium were measured, and 25(OH)DBio was calculated based on VDBP levels. Six common polymorphisms in vitamin D metabolism genes were genotyped. Results: Between-arm net changes were +30.6 ± 1.7 nmol/L for 25(OH)D, +2.7 ± 0.2 nmol/L for 25(OH)DBio, and −5.2 ± 1.2 pg/mL for PTH, corresponding to 70% [95% confidence interval (CI), 62.8% to 77.2%] net reversion rate for vitamin D deficiency at week 20 (P < 0.001). Only 25(OH)DBio change was positively associated with calcium change (P < 0.001). Genetic factors (GC-rs4588/GC-rs7041, VDR-rs2228570, and CYP2R1-rs10741657; P ≤ 0.04) showed stronger influences on 25(OH)D or 25(OH)DBio responses than nongenetic factors, including baseline value, body mass index, and sex. An inverse association of PTH-25(OH)D was demonstrated only at 25(OH)D of <50.8 (95% CI, 43.6 to 59.0) nmol/L. Conclusions: Supplemented 2000 IU/d vitamin D3 raised 25(OH)D and 25(OH)DBio but was unable to correct deficiency in 25% of Chinese participants, which might be partially attributed to the effect of genetic modification. More studies are needed to elucidate appropriate vitamin D recommendations for Asians and the potential clinical implications of 25(OH)DBio.