Background, subjects and methods: Vitamin D insufficiency in older people in the UK is common and may cause secondary hyperparathyroidism and bone loss. In a randomised, double blind intervention trial to optimise “Vitamin D status in Older People’ (VDOP) three oral dosages of vitamin D3 (12 kIU, 24 kIU or 48 kIU/month) were given for 12 months to 375 participants aged over 70 years (ANOVA) adjustment for covariables with results below presented in ascending dose order.
Results: Baseline characteristics, including BMD, 25OHD and PTH did not differ between the groups (all P>0.05) with a mean (S.D.) 25OHD of 35.5 (20.0) nmol/l, rising by 14.3 (12.6), 25.3 (18.0) and 40.6 (20.2) nmol/l respectively (ANOVA, P<0.001) and resulting in plasma 25OHD levels ≥25 nmol/l in 99%, 100% and 100% and ≥50 nmol/l in 63%, 83% and 100% respectively.
BMD at total femur and neck of femur did not change over 12 months (ANOVA for ΔBMD and ANCOVA comparisons between doses, all P>0.05). However, PTH decreased for all three doses by −2.9 (18.4), −2.9 (18.1) and −10.6 (15.4) pg/ml respectively (ANOVA P<0.001 and when adjusted for age, sex, weight, height and baseline 25OHD ANCOVA, P<0.001). There were no cases of hypercalcaemia, renal stones or adverse events attributable to the intervention and there were no group difference in the number of falls.
Summary: We conclude that monthly supplementation with 12 kIU, 24 kIU or 48 kIU/month vitamin D is safe and associated with improvements in vitamin D status in this population at risk of vitamin D deficiency. No significant decrease in BMD was seen with any dose, despite an anticipated decrease of ~0.6% in this age/geographical group.