Change of BMD after Weaning or Resumption of Menstruation in Chinese Women with Different FokI VDR-genotypes: A Randomized, Placebo-controlled, Calcium Supplementation Trial

ObjectiveTo investigate the effect of calcium supplementation on bone mineral density (BMD) in Chinese women with different FokI vitamin D receptor (VDR) genotypes (FF, Ff, and ff) after weaning or resumption of menstruation during lactation.MethodsA total of 40 subjects with the same FokI VDR genotype were randomly divided into two groups: one received calcium tablet (600 mg once daily as CaCO3) and the other placebo tablet once daily for 1 year. At baseline, BMD was measured by dual-energy X-ray absorptiometry at lumbar spine (L2-L4) and at left hip whereas serum PICP, serum OC, and urinary CTX, serum 25(OH)VitD3, and serum estradiol were measured at weaning and 1 year thereafter.ResultsAfter the intervention, BMD at lumbar spine and at left hip increased significantly in all these women with a trend among different FokI VDR genotypes such as FF > Ff > ff (P<0.05, <0.01, and <0.001, respectively). BMD at lumbar spine in women with FF VDR genotype increased much more rapidly than in those with ff VDR genotype (P<0.05). Compared with the control group women with the FF genotype regained more BMD after calcium supplementation (P<0.05).ConclusionDaily calcium 600 mg supplementation has beneficial effect on the bone health of women with FF VDR genotype.