Abstract
More data is urgently required examining the link between poor vitamin D status on bone health and muscle function in different UK ethnic groups. The D-FINES study examined a total of 373 Surrey-dwelling Caucasian (C) and Asian (A) women in four seasons of the year for diet, sunlight exposure, 25-hydroxyvitamin D (25(OH)D) and grip strength (GS). In the autumn season, lumbar spine bone mineral density (LSBMD) was also measured. The specific aim of this work was to examine differences in LSBMD and GS in A and C pre and postmenopausal women according to 25(OH)D. When women were grouped by 25(OH)D (<30 nmol/l, 30-39nmol/l; 40-74nmol/l; 75nmol/l+), ANCOVA adjusting for BMI showed a significant difference in LS BMD between the groups for summer (p=0.042), autumn (p=0.002) winter (p=0.028) and spring (p=0.019) 25(OH)D. The 25(OH)D <30nmol/l and 30-39nmol/l groups had significantly lower LS BMD than those with >75nmol/l. For GS, controlling for lean arm mass, a statistically significant difference between the four ethnic/menopausal groups (F=24.851, p<0.001) was found but no significant within subjects effect of season (F= 0.503, p=0.681) and no significant interaction between season and ethnic/menopausal group (F=0.303, p=0.974). Significant positive partial correlations were found for all women (p<0.001) in all seasons between 25(OH)D and GS. For all C as one group, significant positive correlations were found between 25(OH)D and GS in summer (r=0.307), autumn (r=0.223), winter (r=0.222) and spring (r=0.242), with p<0.001 for all seasons. However, this was not found for the A groups combined, or for the four groups separately (p>0.05). In summary, LS BMD was found to be significantly higher in individuals with 25(OH)D >75nmol/l compared to those with <39nmol/l. These key findings show that poor 25(OH)D is associated with a detrimental effect on bone health. If maintained, these findings could potentially translate into increased fracture risk long-term. Furthermore, 25(OH)D was positively correlated with GS in all women in all seasons, indicating low 25(OH)D may decrease GS, most likely via poorer muscle function. These findings are a cause for public health concern. This work was funded by the UK Foods Standards Agency (NO5064). The views expressed are those of the authors alone.