Evidence Hub

Effects of long-term daily supplementation with vitamin D3 and marine omega-3 fatty acids on change in ADRD biomarkers: A secondary analysis of a randomized clinical trial

Vyas CM, Ostaszewski BL, Anderson AK, Cook NR, Kang JH, Mischoulon D, Reynolds CF, Chang G et al.

Alzheimer's & dementia (New York, N. Y.), 2026

929 participants

Abstract

Abstract INTRODUCTION Vitamin D3 and omega‐3 supplementation may slow outcomes related to Alzheimer's disease and related dementias (ADRD), with variation by sex or race, but their effects on ADRD‐associated biomarkers are unknown. METHODS In this secondary analysis of a randomized clinical trial (RCT), we included 929 participants from the in‐clinic subcohort of the VITamin D and OmegA‐3 TriaL – a completed, placebo‐controlled, 2×2 factorial trial testing vitamin D3 (2000 IU/day) and omega‐3s (1 g/day) for cardiovascular disease and cancer prevention. Plasma ADRD biomarkers were assayed at baseline and 2‐ and/or 4‐year follow‐up. Study outcomes were longitudinal change in four ADRD biomarkers: N‐terminal tau fragment (NT1), amyloid beta (Aβ)40:42, neurofilament‐light (NfL), and glial fibrillary acidic protein (GFAP). Repeated‐measures models were used, with sex and race were pre‐specified effect modifiers. RESULTS The sample mean (SD) age was 65.0 (6.6) years; 49.2% were female, and 8.2% were Black adults. Neither vitamin D3 nor omega‐3s, compared to placebo, significantly reduced ADRD biomarkers over 4 years. Pre‐specified subgroup analyses suggested potential interactions by sex and race. Vitamin D3 supplementation resulted in a reduction in NT1 among males (−2.7%) but not females (p‐interaction = 0.08). Among Black participants, vitamin D3 supplementation resulted in a 16.2% reduction in NfL levels [95% CI: −30.5% to 1.1%; p‐interaction = 0.06], while omega‐3…

How strong is the evidence?

Evidence Hub reads this as a secondary / pooled analysis, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 929 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

Read the paper

Related studies

Go deeper in Evidence Hub

Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.

Open this study Sign up free