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Efficacy of antioxidants as a therapy for Alzheimer's disease: a meta-analysis

Li J, Chen B, Jiang J, Feng Y, Zhang R, Li D, Wang R, Long Z et al.

Frontiers in nutrition, 2026

10,537 participants

Abstract

Background: Oxidative stress plays a central role in the pathogenesis of Alzheimer's disease (AD), contributing to neuronal damage, amyloid-beta aggregation, tau hyperphosphorylation, and neuroinflammation. Although antioxidants have been proposed as potential therapeutic agents, clinical trials have yielded inconsistent results.

Objective: To systematically evaluate the efficacy of various antioxidants-including vitamins, polyphenols, and other antioxidant preparations-on cognitive function, oxidative stress biomarkers, neuropsychiatric symptoms, and disease progression in patients with AD.

Methods: We conducted a systematic search of PubMed, Embase, and Web of Science from inception to October 2, 2025, for randomized controlled trials (RCTs) evaluating antioxidant interventions in AD patients. Study selection, data extraction, and quality assessment were performed independently by multiple reviewers. Meta-analyses were conducted using random-effects models where significant heterogeneity was present (I2 > 50%). Outcomes included cognitive function scales (e.g., ADAS-Cog, MMSE), oxidative stress markers, neuropsychiatric symptoms, daily living abilities, neuroimaging measures, and fluid biomarkers.

Results: A total of 23 RCTs comprising 10,537 participants were included. Antioxidants showed mixed effects across outcomes. While certain oxidative stress markers (urinary 8-iso-prostaglandin F2α: SMD 0.75, 95% CI 0.12-1.38) and neuropsychiatric symptoms (NPI: SMD -0.85, 95% CI…

How strong is the evidence?

Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 10,537 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.

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