Role of nut and seed intake on telomere length as a biomarker of ageing: a systematic review of observational and interventional studies

Telomere length is a biomarker of ageing, with shorter lengths associated with a higher risk of age-related diseases and mortality. Oxidative stress and inflammation predominantly contribute to telomere shortening. Diets rich in antioxidant and anti-inflammatory properties may help preserve telomere length. Nuts and seeds contain antioxidant and anti-inflammatory nutrients and bioactive compounds. Their consumption is recognised as protective against age-related conditions. The objective of this review is to evaluate the role of nut and seed intake on telomere length in humans. A systematic search was conducted in four databases from inception to 12 March 2024 to identify observational and interventional studies assessing nut and seed intake and measuring telomere length as an outcome in adults (aged ≥ 18 years). Data from the included articles were extracted by one reviewer and verified by another reviewer. Out of the nine observational studies included, three reported positive associations between nut and seed intake and telomere length. None of the four interventional studies included reported a significant positive effect. Meta-analysis was not performed due to high variability in reporting telomere length measurements. The evidence is insufficient to confirm a beneficial role of nut and seed intake on telomere length. Adequately powered long-term intervention studies are needed.