Genetic Variations in VDR could Modulate the Efficacy of Vitamin D(3) Supplementation on Inflammatory Markers and Total Antioxidant Capacity among Breast Cancer Women: A Randomized Double Blind Controlled Trial

BACKGROUND: Low levels of vitamin D are found in a great part of breast cancer women. Study subjects using vitamin D(3) supplement had lower rates of cancers and fewer markers of inflammation. Additionally, recent studies demonstrate the power of vitamin D supplementation to lower inflammation and oxidative stress biomarkers associate with VDR polymorphism to reduce inflammation. This study was aimed to assess the impact of vitamin D(3) supplementation on the serum concentration of inflammatory markers and antioxidant capacity with regard to VDR polymorphism in the VDR gene in breast cancer women. METHODS: A randomized, double-blind, placebo-controlled trial was conducted on 56 breast cancer women. Participants were assigned to 2 treatment arms: placebo and vitamin D(3) for 2 months intervention. Supplementation group received 50,000 IU of vitamin weekly. Blood samples were collected at baseline and after the intervention to measure the 25(OH) D(3), TNF-α, TGF- β and TAC. Genotyping was performed for FokI, BsmI, ApaI, and TaqI polymorphism. RESULTS: After eight weeks supplementation, the intervention group showed a significant increase in the serum concentration of 25(OH) D(3) (28±2.6 to 39±3.5; p=0.004 and TAC (48.9±13.3 to 63.5±13.3; p= 0.017). Changes in TNF-α, TGF- β1 were not significant. Serum TAC levels of participants with the TT/Tt, Ff genotypes were more responsive to supplementation. CONCLUSIONS: Supplementation with a vitamin D(3) increased the TAC in breast cancer women, although it had no effect on inflammatory markers. Serum TAC in the TT/Tt, Ff were more responsive to vitamin D supplement compared with those with the FF/ff and tt genotypes.