Abstract
Background: The role of caffeine as a risk factor for bone loss is controversial. 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 interaction between caffeine intake, vitamin D receptor (VDR) polymorphism, and BMD 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 in 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 groups with either low (≤ 300 mg/d) or high (> 300 mg/d) caffeine intakes and between the VDR genotype subgroups of the low- and high-caffeine 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% compared with 1.19 ± 1.08%; P = 0.038). When the data were analyzed according to VDR genotype and caffeine intake, women with the tt genotype had significantly (P = 0.054) higher rates of bone loss at the spine (-8.14 ± 2.62%) than did women with the TT genotype (-0.34 ± 1.42%) when their caffeine intake was > 300 mg/d. Conclusions: Intakes of caffeine in amounts > 300 mg/d (≈514 g, or 18 oz, brewed coffee) accelerate bone loss at the spine in elderly postmenopausal women. Furthermore, women with the tt genetic variant of VDR appear to be at a greater risk for this deleterious effect of caffeine on bone.