Caffeine intake increases the rate of bone loss in elderly women and interacts with vitamin D receptor genotypes

Background: The role of caffeine as a risk factor for bone loss is controve rsial. Objective: Our goals were 1) to compare in both a cross-sectional study and a 3-y longitudinal study the bone mineral density (BMD) of postmenopausal women consuming high or low amounts of caffeine and 2) to study the interac tion between caffeine intake, vitamin D receptor (VDR) polymorphism, and BM D in the longitudinal study. Design: The results are derived from cross-sectional measurements of BMD in 489 elderly women (aged 65-77 y) and from longitudinal measurements made i n 96 of these women who were treated with a placebo for 3 y. Changes in BMD were adjusted for confounding factors and were compared between group, wit h either low (less than or equal to 300 mg/d) or high (> 300 mg/d) caffeine intakes and between the VDR genotype subgroups of the low- and high-caffei ne groups. Results: Women with high caffeine intakes had significantly higher rates of bone loss at the spine than did those with low intakes (-1.90 +/- 0.97% co mpared with 1.19 +/- 1.08%; P = 0.038). When the data were analyzed accordi ng to VDR genotype and caffeine intake, women with the tt genotype had sign ificantly (P = 0.054) higher rates of bone loss at the spine (-8.14 +/- 2.6 2%) than did women with the TT genotype (-0.34 +/- 1.42%) when their caffei ne intake was >300 mg/d. Conclusions: Intakes of caffeine in amounts >300 mg/d (approximate to 514 g , or 18 oz, brewed coffee) accelerate bone loss at the spine in elderly pos tmenopausal women. Furthermore, women with the tt genetic variant of VDR ap pear to be at a greater risk for this deleterious effect of caffeine on bon e.