Circulating 25-Hydroxy Vitamin D Relative to Vitamin D Receptor Polymorphism after Vitamin D3 Supplementation in Breast Cancer Women: A Randomized, Double-Blind Controlled Clinical Trial

Document Type: Research Articles

Authors

1 Department of Nutrition, Faculty of Paramedicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

2 Nutrition and Metabolic Diseases Research Center Ahvaz Jundishapur, University of Medical Sciences, Ahvaz, Iran.

3 Food Security Research Center, Department of Clinical Nutrition, Isfahan University of Medical Sciences, Isfahan, Iran.

4 Infectious and Tropical Diseases Research Center, Research Institute of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

5 Thalassemia and Hemoglobinopathy Research Center, Research Institute of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.

6 Diabetes Research Center, Research Institute of Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran

Abstract

Objective: The influence of vitamin D receptor (VDR) genetic variation on serum 25-hydroxyvitamin D levels
[25(OH)D] after vitamin D3 supplementation remains unclear. We aimed to investigate changes of 25(OH)D in a
randomized, double-blind, placebo-controlled clinical trial, according to VDR genotype, after provision of vitamin D3 to
breast cancer cases for a 2-month period. Methods: Participants were assigned to two treatment arms: placebo (n = 28) and vitamin D3 supplementation (n =28). The supplementation group received 50,000 IU of vitamin D every week for 2 months. Blood samples were collected at baseline and after intervention to measure serum 25(OH) D3. Genotypes were
assessed for FokI, BsmI, ApaI, and TaqI polymorphisms. Results: After eight weeks supplementation, the rvention
group showed a significant increase in the serum concentration of 25(OH) D3 (28±2.6 to 39±3.5; p=0.004). Subjects
were then classified into twelve subgroups according to different VDR genotypes. Subjects with ff/Ff, TT/Tt, and Bb
genotypes had significantly higher increases in serum 25(OH)D compared to those with FF, tt, and BB/bb genotypes
post-intervention. Serum vitamin D3 levels with the AA genotype were lower than with aa/ Aa. No differences were
found among other subgroups. Conclusion: Vitamin D3 supplementation increases serum 25(OH)D in women with
breast cancer. Serum vitamin D3 in TT/Tt, ff/Ff, and Bb carriers was more responsive to vitamin D supplementation
than in those with FF/ff and tt genotypes. Other subgroups might gain less from vitamin D3 supplementation.

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