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Hyperhomocysteinemia, a risk factor for various health conditions: an umbrella review of systematic reviews with meta-analysis

Castagna A, Cotroneo AM, Mosele M, Sapone P, Martinelli E, Rahmati M, Smith L, Veronese N

Aging clinical and experimental research, 2026

953,793 participants

Abstract

Background: Hyperhomocysteinemia, an elevation of plasma homocysteine levels, has been implicated in multiple diseases, yet its causal role remains debated. This umbrella review systematically evaluated and graded the evidence from published systematic reviews and meta-analyses on associations between hyperhomocysteinemia and diverse health outcomes.

Methods: We searched Medline, Embase, and Web of Science up to March 5, 2025. Eligible studies were systematic reviews and meta-analyses of observational studies reporting associations between hyperhomocysteinemia and any health outcome. Methodological quality was assessed using AMSTAR-2, and the certainty of evidence was graded using GRADE.

Results: A total of 104 meta-analyses including 2,110 studies and 953,793 participants were analyzed, covering 126 outcomes. Eighty-three percent of outcomes showed significant associations with hyperhomocysteinemia. Nine outcomes were supported by high, 18 by moderate, 73 by low, and 26 by very low certainty of evidence. High-certainty evidence supported associations between hyperhomocysteinemia and increased risks of stroke, intracerebral haemorrhage, fracture (hip and total), and chronic kidney disease. Moderate-certainty evidence linked hyperhomocysteinemia to dementia, Alzheimer's disease, mortality, and selected cardiovascular and pregnancy outcomes. Most meta-analyses were of low or critically low methodological quality.

Conclusions: Across nearly one million participants,…

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: 953,793 participants or records.

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