Bone mineral density (BMD) is the measure of the absolute amount of bone. It correlates well with the general health of the bone, its strength and its ability to bear weight (1) . The measurement of BMD allows for the prediction of fracture risk (2) . Little is known about the effect of ethnicity on diet, physical activity and BMD. Thus, the principal aim of the present study was to investigate the effect of season and ethnicity on axial and peripheral BMD in UK pre-and post-menopausal women. The specific objective was to determine whether there was a seasonal variation in lumbar spine and femoral neck (FN) BMD in Caucasian and Asian women living in the UK.The BMD data were collected from the D-FINES study, which included seasonal data on 242 Caucasian and seventy-two Asian women aged 19-70 years (mean age (years) 50.4 (SD 14.3) and 49.7 (SD 11.6 respectively) over a period of 12 months. Women were randomly recruited through general practitioners or through Asian community networks in Woking, Kingston and Thornton Health. BMD was measured in autumn 2006 (September-December) and spring 2007 (March-June) by dual X-ray absorptiometry (QDR; Hologic Inc., Bedford, MA, USA). Other measurements undertaken included data on dietary intake and fasted blood samples for assessment of vitamin D status. Ethnicity . . . Caucasian Asian Autumn Spring Autumn Spring Mean SD Mean SD Mean SD Mean SD FN BMD (g/cm 2 ) 0.792 a 0.109 0.787 b 0.111 0.805 0.104 0.806 0.113 FT BMD (g/cm 2 ) 0.807 a 0.122 0.714 b 0.100 0.709 0.123 0.713 0.162 FW BMD (g/cm 2 ) 0.672 0.152 0.676 0.153 0.675 0.133 0.683 0.139 F total T score -0.346 0.984 -0.398 0.958 -0.227 0.839 -0.255 0.875 FT, femoral trochanter; FW, femoral Ward's triangle; F, femoral. a,b Values with unlike superscript letters were significantly different (paired t test; P < 0.05).The Table shows that in Caucasian women autumn BMD was significantly higher when compared with spring BMD at the hip BMD sites, which remained significant after adjustment for dietary Ca and vitamin D intake. However, no seasonal differences were found in the Asian women. The novel seasonal data in ethnic groups may possibly be explained by variations in vitamin D (25-hydroxyvitamin D) status (3) in Caucasian women but not Asian women and this finding requires further investigation. Analysis is now underway to explore the association between bone health, anthropometrics and vitamin D metabolism (including 25-hydroxyvitamin D status, parathyroid hormone and serum Ca) in the D-FINES dataset.

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There are limited studies on factors determining bone mineral density (BMD) in South Asians (SA) women of UK origin. BMD of SA women is found to be lower than that of Caucasians (Cau), but often this difference has been confounded in a number of studies by body size (1,2) . The aim was to examine factors modulating variation in BMD, bone mineral content (BMC) and bone area (BA) among SA and Cau women of UK origin.The data are derived from the D-FINES Study examining the effect of vitamin D status on bone health of women living in Surrey, UK. In the present study Autumn (September-December 2006) data from 185 premenopausal women (Cau: n 135, age 33.9 (SD 5.6) years; SA: n 50, age 38.0 (SD 8.9) years) were examined. Bone mass and body composition were measured by dual X-ray absorptiometry (DXA; Hologic QDR; Hologic UK Ltd, Crawley, West Sussex, UK). Other measurements taken included dietary intake, physical activity (PA) level, hand-grip strength and serum concentrations of 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH).Trochanter BMD (TroBMD), spinal BMC (LSBMC), spinal bone area (LSBA), total body BMD (TBMD), total body BMC (TBMC) of SA were all significantly lower than those of Cau (P < 0.025). Furthermore, SA had significantly lower height, hand-grip strength, PA level and serum 25OHD than Cau (P £ 0.004). However, PTH of SA was significantly higher than that of Cau (P < 0.0001). Dietary Ca and vitamin D intake did not differ between SA and Cau. Univariate correlation between bone mass measures and other variables was determined. Variables with P < 0.05, i.e. age, weight, height, BA, serum 25OHD and PTH, hand-grip strength, PA level, total fat mass (TFM; by DXA) and menarche age were then entered into the regression models to determine their relative contribution to the variation in bone mass.Ethnic differences in TroBMD, LSBMC, LSBA, TBMD and TBMC were not found when adjustment was made for age, weight and height in the initial regression models. For TroBMD, weight (P = 0.04), BA (P < 0.0001) and serum 25OHD (P = 0.033) remained significant determinants in the final model (adjusted R 2 45 %). For LSBMC, weight (P = 0.006) and LSBA (P < 0.0001) were significant determinants in the initial model (adjusted R 2 67.6 %). However, weight was not significant when 25OHD (P = 0.022) entered the model (adjusted R 2 68 %). For TBMC, weight and height (P < 0.0001), 25OHD (P = 0.035), and TFM (P = 0.003) remained significant in the final model to predict TBMC variation (adjusted R 2 60.7 %). For TBMD, weight (P = 0.001), 25OHD (P = 0.018) and TFM (P = 0.032) were significant determinants of TBMD after adjusting for other covariates (adjusted R 2 31 %).These findings suggest that lower bone mass among premenopausal SA women living in England was associated with their smaller body size. Body weight was found to be a consistent determinant of bone mass in various skeletal sites after adjusting for confounding factors. It is important to note that serum vitamin D status was a very significant determinant of the va...