The relationship between vitamin D and risk of atrial fibrillation: a dose-response analysis of observational studies

Systematic review and dose-response meta-analysis of observational studies in adults from the general population and patients undergoing CABG, focused on the association between circulating 25(OH)D and atrial fibrillation risk. Arm-level details were available for one randomized vitamin D arm from Özsin 2018 in Turkey, but the review evidence itself was primarily observational.

Vitamin D was evaluated as the active supplement exposure, with the only arm-level randomized detail available for Özsin 2018 in Bursa, Turkey, where 50 participants were randomized to the vitamin D arm; the dose, formulation, frequency, and duration were not reported in the provided text. The review also examined circulating 25(OH)D levels and AF/POAF risk rather than a standardized supplementation regimen across studies.

Vitamin D deficiency was associated with a higher risk of atrial fibrillation and postoperative AF after CABG, while higher circulating vitamin D was associated with lower AF risk. In dose-response analyses, each 10 ng/mL increase in vitamin D was associated with a reduced risk of AF, with an inverse relationship and no strong evidence of nonlinearity for AF. For POAF, data were limited but suggested a protective effect. The association appeared stronger in adults aged 65 years or older, and the authors concluded that prospective and interventional studies are still needed to determine whether vitamin D supplementation prevents AF.

The evidence was based mainly on observational studies, so causality and supplement efficacy cannot be confirmed. POAF analyses were limited by few studies and smaller pooled samples, and the review called for prospective and interventional data. The reported randomized arm lacked dosing and outcome detail in the provided text, and subgroup findings by age may limit generalizability.