Vitamin D metabolism-related genetic variants, dietary protein intake and improvement of insulin resistance in a 2 year weight-loss trial: POUNDS Lost
Bray, George A.
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CitationQi, Qibin, Yan Zheng, Tao Huang, Jennifer Rood, George A. Bray, Frank M. Sacks, and Lu Qi. 2015. “Vitamin D Metabolism-Related Genetic Variants, Dietary Protein Intake and Improvement of Insulin Resistance in a 2 Year Weight-Loss Trial: POUNDS Lost.” Diabetologia 58 (12) (September 29): 2791–2799. doi:10.1007/s00125-015-3750-1.
Vitamin D and related genetic variants are associated with obesity and insulin resistance. We aimed to examine whether vitamin D metabolism-related variants affect changes in body weight and insulin resistance in response to weight-loss diets varying in macronutrient content.
Three vitamin D metabolism-related variants, DHCR7 rs12785878, CYP2R1 rs10741657 and GC rs2282679, were genotyped in 732 overweight/obese participants from a 2 year weight-loss trial (POUNDS Lost). We assessed genotype effects on changes in body weight, fasting levels of glucose and insulin, and HOMA-IR at 6 months (up to 656 participants) and 2 years (up to 596 participants) in response to low-protein vs high-protein diets, and low-fat vs high-fat diets.
We found significant interactions between DHCR7 rs12785878 and diets varying in protein, but not in fat, on changes in insulin and HOMA-IR at both 6 months (p for interaction <0.001) and 2 years (p for interaction ≤ 0.03). The T allele (vitamin-D-increasing allele) of DHCR7 rs12785878 was associated with greater decreases in insulin and HOMA-IR (p < 0.002) in response to high-protein diets, while there was no significant genotype effect on changes in these traits in the low-protein diet group. Generalised estimating equation analyses indicated significant genotype effects on trajectory of changes in insulin resistance over the 2 year intervention in response to high-protein diets (p < 0.001). We did not observe significant interaction between the other two variants and dietary protein or fat on changes in these traits.
Our data suggest that individuals carrying the T allele of DHCR7 rs12785878 might benefit more in improvement of insulin resistance than noncarriers by consuming high-protein weight-loss diets.
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