DIETARY VITAMIN-C AND BONE-MINERAL DENSITY IN POSTMENOPAUSAL WOMEN INWASHINGTON-STATE, USA

Study objective-To examine the relationship between dietary vitamin C and hip bone mineral density (BMD) in postmenopausal women. Design-Thi s was a cross sectional study using retrospective diet and vitamin sup plement data. Setting-The Seattle area of Washington State. Participan ts-Screenees for a clinical trial of a drug to prevent osteoporotic fr actures; 1892 women aged 55-80 years who had hip bone densitometry and osteoporosis risk factor information. Main results-Mean energy adjust ed dietary intake of vitamin C was 113 mg/day; including supplement us e, mean intake was 407 mg/day. There were no differences in BMD accord ing to diet-only vitamin C intake or combined dietary and supplemental vitamin C intake. Longer duration of vitamin C supplement use was ass ociated with higher BMD in women who had not used oestrogen replacemen t therapy (trend p=0.02) and among women aged 55-64 years (trend p=0.0 1). Women aged 55-64 years who used vitamin C supplements for greater than or equal to 10 years had a higher BMD than non-users aged 55-64 y ears (multivariate adjusted mean BMD 0.699 (0.017) g/cm(2) versus 0.65 5 (0.007) g/cm(2), p=0.02). Benefits were not evident in older age gro ups or in women who had used oestrogen in the past. Frequent intake of foods rich in vitamin C was not associated with BMD. Conclusion-There was no evidence that vitamin C from the diet was associated with BMD, although long term use of vitamin C supplements was associated with a higher BMD in the early postmenopausal years and among never users of oestrogen.