Effects of almond intake on oxidative stress parameters: A systematic review and meta-analysis of clinical trials.

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• Nuts are a rich source of antioxidants, particularly vitamin E and polyphenols.
• This review suggests that incorporating almonds into the diet may help reduce malondialdehyde (MDA) levels, a marker of oxidative stress, indicating potential antioxidant benefits.
• However, the effect of almond consumption on oxidised low-density lipoprotein (Ox-LDL) and other oxidative markers remains inconclusive; therefore findings should be interpreted with caution.

Introduction: A meta-analysis was conducted to evaluate the impact of almond consumption on selected oxidative stress markers.

Method:

• Databases including PubMed, Scopus, Web of Science databases, and Google were searched, resulting in the analysis of seven studies involving 424 adult male and female (ages 22-64 years) participants.
• The review followed the Cochrane Collaboration risk of bias tool to assess the individual studies.
• The primary outcomes of malondialdehyde (MDA) and oxidised low-density lipoprotein (Ox-LDL) were measured over a period of 4-28 weeks.

Results:

• A pooled analysis of only three randomised control trials (RCTs) on MDA levels revealed a significant decrease following almond intake (weighted mean difference: -6.63nmol/ml 95% CI: -8.72 to 4.54: p=0.001).
• In contrast, five RCTs showed no significant effect of almond consumption on Ox-LDL levels (Hedges’ g:-0.12:95CI: -0.34 to 0.10: p=0.28).
• There was no evidence of heterogeneity between studies, and sensitivity analysis confirmed that excluding any single trial did not alter the overall findings.

Conclusion:

• This meta-analysis highlighted that almond consumption may reduce MDA levels, indicating potential antioxidant benefits. However, their effect on Ox-LDL was not significant. Based on the limited number of studies explored, these findings must be interpreted with caution.

• Diet and nutrition play an important role in modulating oxidative stress levels.
• The antioxidant properties of almonds have been well studied, although results remain inconclusive.
• Clinical practitioners might consider recommending almonds as part of a balanced diet for patients wanting to combat oxidative stress.
• However, due to their high oxalate content, almonds should be consumed with caution by individuals prone to kidney stones.
• Excessive almond consumption may also lead to potential side effects, including allergies, nausea, and digestive issues

• The number of studies included in this review were limited, with significant variability in almond types (almond powder and snacks) and amount. •Larger, more comprehensive studies are needed to better understand the effect of almonds on oxidative stress markers.
• Future studies should aim to investigate the bioavailability and impact of different preparation and processing methods (e.g., soaking, grinding) of almonds, and subsequent impact on oxidative stress markers.
• Research on other markers of oxidative stress, such as total antioxidant capacity, superoxidase dismutase, catalase, glutathione peroxidase, and reactive oxygen species (ROS) is currently insufficient. Further studies are needed to explore the impact of almond intake on these important biomarkers at rest.