Vitamin D supplementation for the prevention of depression and poor physical function in older persons: the D-Vitaal study, a randomized clinical trial

Randomized clinical trial in community-dwelling older adults at risk of depression and poor physical functioning in Amsterdam and surrounding areas, the Netherlands, conducted from 2013 to 2016. The vitamin D3 arm included 77 randomized participants; baseline median age was 67.8 years and 58.4% were women, with relatively low vitamin D status at entry.

Participants in the active arm received vitamin D3 1200 IU/day for 12 months, given as 3 oral tablets of 400 IU cholecalciferol (Devaron), compared with identical placebo tablets. Participants could also take up to 400 IU/day from other supplements; calcium intake was supported by dairy advice, and 500 mg/day calcium was provided only to those not reaching at least 2 dairy servings per day.

Vitamin D3 supplementation did not improve depressive symptoms, physical performance, or most secondary outcomes over 12 months versus placebo. The primary outcomes showed no significant between-group differences, with interaction terms P > 0.10. Serum 25(OH)D rose substantially in the vitamin D3 arm at 6 months (85 ± 16 nmol/L vs 43 ± 18 nmol/L in placebo; P < 0.001), confirming biological exposure, but this did not translate into clear clinical benefit. A higher baseline 25(OH)D subgroup showed fewer functional limitations with vitamin D3 (OR = 0.21; 95% CI: 0.05, 0.88; P = 0.032), but this was exploratory and not robust. Adverse events were similar between groups overall, with one death in the intervention arm.

The active arm was modest in size, limiting power for clinical outcomes and subgroup analyses. The baseline 25(OH)D subgroup finding for functional limitations was exploratory and not robust, and the study found no consistent benefit across primary or secondary endpoints. Generalizability is limited to older community-dwelling adults with relatively low vitamin D status in a Dutch setting.