Objective: Vitamin D deficiency (serum 25-hydroxyvitamin D˂25nmol/L) is extremely common in western-dwelling South Asians but evidence regarding vitamin D supplement usage in this group is very limited. This work identifies demographic, dietary and lifestyle predictors associated with vitamin D supplement use.

Design: Cross-sectional analysis of baseline vitamin D supplement use data.

Setting: UK Biobank cohort.

Subjects: In total, n 8024 South Asians (Bangladeshi, Indian, Pakistani), aged 40-69 years.

Results: Twenty-three % of men and 39% of women (P˂0.001) [22% of Bangladeshis, 32% of Indians, 25% of Pakistanis (P˂0.001)] took a vitamin D containing supplement. Median vitamin D intakes from diet were low at 1.0-3.0 micrograms per day, being highest in Bangladeshis and lowest in Indians (P˂0.001). Logistic regression modelling showed that females had a higher odds of vitamin D supplement use than males (odds ratio (OR) = 2.02; 95% confidence interval (CI) 1.79 to 2.28). A lower supplement usage was seen in younger persons (40-60 years) (OR=0.75; 95% CI 0.65 to 0.86 reference= ˃60 years), and those living outside of Greater London (OR=0.53 to 0.77), with borderline trends for a lower body mass index, higher oily fish intake and higher household income associated with increased odds of vitamin D supplement use.

Conclusions: Vitamin D supplements were not used by most South Asians and intakes from diet alone are likely to be insufficient to maintain adequate vitamin D status. Public health strategies are now urgently required to promote the use of vitamin D supplements in these specific UK South Asian sub-groups.