Aims: The objective of this study was to determine whether vitamin D and genistein supplementation had an additive beneficial effect on levels of vitamin D and bone markers and whether this effect was mediated by genes regulating isoflavone metabolism. Materials and Methods: We carried out a prospective study in postmenopausal women randomized to calcium and vitamin D supplementation or calcium, vitamin D, and genistein supplementation. Vitamin D, parathyroid hormone (PTH), cross-linked C-telopeptide (CTX), and procollagen 1 N-terminal (P1NP) were determined by electrochemiluminescence. Three SNPs - rs2231142 (ABCG2), rs358231 (cytosolic β-glucosidase [CBG]), and rs2273697 (ABCC2) - were determined. Results: We included 102 women. The effects on bone remodeling were similar: rises in vitamin D were significantly associated with reductions in PTH, CTX, and P1NP. Pharmacogenomic analysis of the genotypes showed that, in AT heterozygotes of the CBG1368T>A polymorphism, CTX and P1NP were not reduced. Conclusion: Genistein added to calcium and vitamin D supplementation had no additional effect. The supplementation of individual AT heterozygotes of the CBG1368T>A polymorphism had no effect on markers of bone remodeling.

Abstract. Objective: The aim of this study was to evaluate the relationship between vitamin D levels at baseline and after 12 weeks of supplementation/exposure to sunlight and VDR genotypes (BsmI, TaqI and ApaI) and haplotypes in a homogeneous population of postmenopausal women. Methods: We made a prospective study in which 151 women were randomized to two groups: One with 1000 mg of calcium and 800 IU vitamin D supplementation (102 women) and a placebo group with neither calcium or vitamin D supplementation (49 women). The follow-up was from May to September 2012.Vitamin D was determined by chemiluminescent immunoassay. Genotypes were determined using the Sequenomi Plexplatform and haplotypes using PHASE software. Results: Baseline (25 ± 10 ng/ml vs.23 ± 9 ng/ml, p > 0.05) and 12-week (32 ± 8 ng/ml vs.29 ± 10 ng/ml, p > 0.05) vitamin D levels were similar between the two groups. The genetic study was made in the total population. There were no differences in baseline and final levels of vitamin D in terms of genotypes and haplotypes, except for the Bat haplotype, whose baseline values were lower (25OHD: 21 ± 10 ng/ml vs. 21 ± 10 ng/ml, p = 0.038). The rate of nonresponders in this group was 15 % (p = 0.001), compared with 9 %, 2 % and 3 % in the other groups. Conclusions: The Bat haplotype was associated with lower baseline levels of vitamin D and a worse response to supplementation and, therefore, may be a risk factor for vitamin D deficiency.

Background: In vitro studies have shown that genistein inhibits the CYP240 enzyme, which is involved in the degradation of 1,25-dihydroxycholecalciferol and its precursor 25-hydroxycholecalciferol, and increases their plasma levels. However, no clinical studies have primarily assessed the synergistic effect of isoflavones on vitamin D levels. The aim of this study was to evaluate the possible additive effect of genistein supplementation on vitamin D levels, calcium metabolism and bone remodeling markers in healthy postmenopausal women during the spring-summer months. Patients and methods: We made a prospective, double-blind study with 150 healthy postmenopausal women that were randomized to three groups. One received placebo, another received calcium (1000 mg/day) and vitamin D (cholecalciferol, 800 U/day) and the third received calcium (1000 mg/day), vitamin D (cholecalciferol, 800 U/day) and genistein (90 mg/day). The study period was from May to September (spring-summer). Vitamin D, PTH, CTX and P1NP were determined by electrochemiluminescence at baseline and after 12 weeks. Results: Vitamin D levels increased in all groups: placebo (23±9 ng/ml vs. 29±10 ng/ml, p<0.05), calcium+vitamin D (26±10 ng/ml vs. 33±8 ng/ml, p<0.05) and calcium+vitamin D+genistein (24±9 ng/ml vs. 31±8 ng/l, p<0.05) without between-group differences. At study end, the percentage of women with vitamin D <20 ng/ml (11%) and <30 ng/ml (39%) had fallen without between-group differences. The effects on calcium metabolism and bone remodeling markers were similar between groups: rises in vitamin D were significantly linked to reductions in PTH, CTX and P1NP. Conclusion: Adding genistein to supplementation with calcium and vitamin D provided not additional changes in vitamin D levels, calcium metabolism or bone remodeling markers in healthy Spanish postmenopausal women during the spring-summer months.