August 27, 2025, 2:12 pm | Read time: 5 minutes
Will eating almonds daily become the new daily apple for doing something good for your health? For a meta-analysis, researchers evaluated clinical studies that examined the impact of almonds on biomarkers for oxidative stress. This is a crucial factor for cell health and inflammatory sparks in the development of chronic diseases. FITBOOK nutrition expert Sophie Brünke presents the findings and reveals in what form almonds are healthiest.
Scientists Analyzed Eight Clinical Studies
The researchers searched the databases PubMed, Scopus, and Web of Science according to PRISMA guidelines for systematic reviews. They included only randomized controlled trials (RCTs) and crossover studies with adult participants published up to January 2025. Observational studies were excluded because they do not allow conclusions about causality, meaning no direct cause-and-effect relationships.
Out of 1,350 identified papers, eight studies met the authors’ criteria after review. This included five RCTs, three crossover studies, and a total of 424 participants. The subjects in the included studies were either healthy, overweight, smokers, or suffered from chronic conditions such as coronary heart disease or hyperlipidemia. The almond amounts studied ranged from five to 168 grams daily. The study duration varied between four and 24 weeks. The effect of almonds on various markers for oxidative stress was measured, including:
- Lipid peroxidation (such as malondialdehyde, MDA)
- Oxidative DNA damage (8-hydroxy-2’-deoxyguanosine, 8-OHdG)
- Uric acid (UA)
- Antioxidant enzymes like superoxide dismutase (SOD) and glutathione peroxidase (GPx)
The authors used a so-called random-effects model for evaluation, which also considers differences between the studies. For each biomarker change, they calculated the weighted mean difference (WMD) and presented the result with a 95 percent confidence interval. Heterogeneity between the studies was assessed using I² values.
What Exactly Is Oxidative Stress?
Oxidative stress occurs when free radicals (aggressive oxygen compounds) overwhelm the body’s defense systems. These include both the body’s own “defense enzymes” (examined in the study: SOD and GPx) and antioxidants from food, such as vitamin E from almonds. Oxidative stress damages cells, proteins, and DNA and is considered a central mechanism in the development of chronic diseases like arteriosclerosis, diabetes, or neurodegenerative diseases.
Effects Were Seen From 60 Grams of Almonds Daily
The review results showed a dose-dependent effect, with effects primarily occurring at doses above 60 grams of almonds daily.1 This corresponds to about two handfuls or 50 to 60 almonds. However, the study authors emphasize that the heterogeneity between the studies was very high for the markers of the body’s defense enzymes (SOD and GPx), indicating differences in dosage, duration, participant groups, or processing forms (raw, roasted, peeled).
Specifically, the markers showed the following changes:
- MDA: From 60 grams of almonds per day, MDA decreased significantly
- 8-OHdG: Reduction in value at every dosage
- UA: Reduction in value at every dosage
- “Defense enzyme” SOD: Significantly increased activity overall; due to study heterogeneity, it’s unclear if only at a certain dose
- “Defense enzyme” GPx: No significant change
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Significance of the Study Results
Previous individual studies already showed indications of beneficial effects of almonds, such as on blood values or markers for DNA damage. The present meta-analysis fills the gap in a comprehensive assessment of the overall situation. It provides strong evidence that almonds, in sufficient quantities, measurably counteract oxidative stress. Particularly relevant is the significant reduction of 8-OHdG, a marker for DNA damage associated with cancer and aging processes. The reduction of UA can also be significant, as elevated levels increase the risk of cardiovascular diseases and gout.
For everyday life, this means: Almonds are not only a healthy snack but could be considered a “functional food”—a food with proven health benefits. However, it should be noted: The positive effects only appear at relatively high amounts—60 grams provide around 400 calories with little volume, which does not necessarily make them diet-friendly. For people at increased risk from oxidative stress, such as smokers or patients with heart disease, these results could still be interesting.
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Study Assessment
The meta-analysis is methodologically sound and based on clinical studies with control groups—the gold standard in nutrition research. However, there are limitations: Only eight studies with 424 participants were included. Additionally, the variability in some biomarkers between the studies was very high. Differences in populations, dosages, study duration, and almond processing (raw, roasted, peeled) make definitive statements difficult. Lastly, practical implementation in everyday life is not necessarily feasible. High-quality almonds are not only an expensive product, but 60 grams are also very energy-rich.
Conclusion
The meta-analysis shows: Almonds can measurably reduce oxidative damage in the body—especially at higher amounts over 60 grams per day. Thus, almonds have the potential to be a valuable food for the prevention of chronic diseases. At the same time, the high variability of the results indicates that further well-standardized studies are needed to determine the optimal dose and conditions for maximum benefit.