Eating over 60g of almonds a day might defend DNA and lower oxidative harm

Scientists say high-dose almond consumption may assist protect your cells from oxidative hurt whereas enhancing your physique’s pure protection techniques, however the advantages rely on the dose and the way the nuts are ready.

Study: The impact of almond supplementation on oxidative stress biomarkers: a systematic review and meta-analysis of randomized control trials. Image Credit: shine.graphics / Shutterstock

In a latest systematic overview printed within the journal Scientific Reports, researchers collated, synthesized, and meta-analyzed the outcomes of eight scientific trials to validate and elucidate the impacts of almond supplementation in adults.

Review findings reveal a dose-dependent relationship whereby consuming over 60 grams (g) of almonds each day was noticed to considerably scale back sure markers of mobile harm (notably MDA and 8-OHdG) and, in some analyses, enhance the physique’s antioxidant enzymes (SOD general, although not considerably within the >60 g/day subgroup).

These outcomes help the function of almonds as a possible practical meals for managing oxidative stress, although the authors emphasize that extra standardized trials are wanted earlier than contemplating public well being coverage suggestions, significantly given the excessive variability in outcomes and the affect of things comparable to almond preparation, baseline oxidative stress standing, and participant traits.

Background

Cells are underneath fixed assault from reactive oxygen species (ROS), unstable molecules which can be identified to break lipids, proteins, and even DNA, leading to mutations and related illnesses. Oxidative stress is an imbalance between these damaging free radicals and the physique’s antioxidant defences, exacerbated by environmental air pollution and poor behavioral selections (e.g., suboptimal diets and smoking).

Over time, this ROS-mediated mobile harm accumulates and has been recognized as a number one reason for continual situations, together with heart problems (CVD), diabetes, cancers, and neurodegenerative problems.

Current oxidative stress investigations contain the estimation of biomarkers like malondialdehyde (MDA) for lipid harm, 8-hydroxy-2′-deoxyguanosine (8-OHdG) for DNA harm, and antioxidant enzymes like superoxide dismutase (SOD) as proof for affected person antioxidant efficiency. Despite these surveillance and diagnostic strategies, the worldwide burden of oxidative stress continues to rise.

Almonds (particularly, the fruits of the Prunus amygdalus or Prunus dulcis tree) are wealthy in protecting antioxidant compounds, together with vitamin E, polyphenols, and wholesome monounsaturated fat, making them a promising dietary instrument to fight oxidative stress. While earlier research have been encouraging, their restricted pattern sizes made findings confounding and ungeneralizable, requiring a complete evaluation to consolidate their cumulative proof.

About the overview

The current systematic overview addresses this information hole by collating and reanalyzing knowledge from a number of randomized managed trials (RCTs) geared toward quantifying the impact of almond consumption on oxidative stress. The overview adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) tips.

The complete literature search comprised a customized key phrase search of a number of on-line scientific repositories, together with Scopus, PubMed/Medline, and the Web of Science from database initiation until January 2025. A two-phase screening course of was employed to determine solely publications analyzing adults (≥ 18 years), the place almond supplementation of any kind was the intervention, and outcomes have been reported utilizing oxidation standing biomarkers. Any RCTs or crossover trials assembly these standards have been included in subsequent analyses.

Extracted knowledge included estimates of key biomarkers, and analyses leveraged a random-effects mannequin to pool the outcomes and calculate the weighted imply distinction (WMD; general impact). Crucially, subgroup evaluation was performed to find out if the dose of almonds, particularly, lower than or greater than 60 grams each day, influenced noticed outcomes.

Review findings

Title, summary, and full textual content screening recognized eight high-quality trials (5 parallel RCTs and three crossover trials) that met inclusion standards (n = 424 contributors). Summary statistics revealed that the included examine populations have been various, together with wholesome people, people who smoke, and sufferers with continual illnesses. The almond interventions various in dose, starting from 5 to 168 grams each day, and lasted between 4 and 24 weeks.

Meta-analysis outcomes revealed that the antioxidant results of almonds are partly dose dependent. While decrease doses confirmed minimal influence, supplementation with 60 grams or extra each day (~2 massive handfuls) produced important enhancements in particular key biomarkers, significantly these indicative of mobile harm (MDA and 8-OHdG).

Levels of MDA, a product of lipid peroxidation, have been decreased by a weighted imply distinction of -0.46 (p = 0.002) within the high-dose subgroup, and 8-OHdG, a marker of oxidative DNA harm, was lowered by -5.83 (p < 0.001). In addition, the physique’s endogenous antioxidant defenses have been noticed to be improved general, with SOD exercise rising by 2.02 (p = 0.008) within the pooled evaluation, although the >60 g/day subgroup didn’t attain statistical significance.

Almond consumption additionally led to a small however important discount in uric acid ranges (WMD = -0.64, p = 0.009), which the authors recommend could also be associated to inhibition of xanthine oxidase exercise, a key supply of uric acid and reactive oxygen species. Its influence on glutathione peroxidase (GPx) was not statistically important. Notably, heterogeneity evaluations established a excessive diploma of variability throughout the research for some outcomes (I² > 90%), implying that variations in examine design, almond preparation (uncooked vs. roasted, blanched vs. unblanched), lack of polyphenols from pores and skin elimination, potential genetic variability in antioxidant enzyme responses, and interactions between almond fiber and polyphenols influencing intestine microbiota and systemic oxidative standing doubtless contributed to inconsistent outcomes.

Conclusions

This systematic overview and meta-analysis present proof that almond supplementation can assist handle oxidative stress, significantly for some biomarkers, and that advantages for MDA could also be extra evident at doses larger than 60 grams per day. Not all biomarkers responded in a dose-dependent method, and SOD enhancements have been noticed general however not considerably within the high-dose subgroup.

These findings help the classification of almonds as a possible practical meals. Still, the excessive variability between research highlights a vital want for future analysis. The authors name for extra standardized trials to pinpoint almonds’ optimum dosage, period, and kind to maximise their antioxidant advantages, ideally utilizing constant almond preparation strategies and stratifying contributors by baseline oxidative stress ranges to raised goal populations most certainly to profit.