The Effects of Vitamin D Supplementation on Physical Function and Quality of Life in Older Patients With Heart Failure: A Randomized Controlled Trial

Randomized, double-blind, placebo-controlled trial in older adults with chronic systolic heart failure and vitamin D insufficiency recruited from primary and secondary care in Scotland. The active vitamin D2 group consisted of older participants with mean age 78.8 years; 34 (64) were male, and all participants were of white European origin.

Oral ergocalciferol (vitamin D2) 100,000 U was given at baseline and repeated at 10 weeks, with dosing supervised in the participant's home. The comparator was placebo.

Vitamin D2 supplementation did not improve physical function, daily activity, or quality of life in older patients with heart failure and vitamin D insufficiency. The 6-minute walk distance showed no between-group benefit at 10 weeks (difference -2.4, 95% CI -17.1 to 12.4; P=0.75) or 20 weeks (difference -5.6, 95% CI -22.2 to 11.0; P=0.51), and Timed Up and Go and Functional Limitations Profile results were also null. The main clinical signal was a modest improvement in Minnesota Living With Heart Failure score at 20 weeks (between-group difference 5.3, 95% CI 0.5 to 10.2; P=0.03), but this did not translate into better exercise capacity or daily activity. BNP fell more with vitamin D2 than placebo at 10 weeks (between-group difference -34; P=0.04) and 20 weeks (-52; P=0.05), while TNF-alpha was unchanged.

Small single-trial sample and short follow-up limited power to detect modest clinical effects. Outcomes were heterogeneous, with a biomarker signal that did not align with the main functional endpoints, and the population was restricted to older white patients in Scotland, which limits generalizability.