Could 4-Week Walnut Consumption Influence Oxidative and Inflammatory Status in Middle-Aged Adults with Cardiometabolic Risk Factors? Findings from a Randomized Controlled Trial.

BACKGROUND

Oxidative stress (OS) and inflammation are interconnected processes with significant roles in various chronic diseases, particularly those associated with aging, such as metabolic syndrome (MetS). Recent evidence suggests that walnuts (from L.), due to their rich content of phytochemicals, have antiaging potential by attenuating OS and chronic low-grade inflammation, known as inflammaging.

OBJECTIVES

We aimed to assess the impact of daily walnut consumption for 4 weeks on biomarkers of OS and inflammation in a cohort of middle-aged individuals at risk of developing MetS.

METHODS

In this crossover randomized controlled trial (RCT), 22 participants (mean age: 48.81 ± 4.3 years) underwent two 28-day dietary interventions separated by a one-month washout period. One intervention period included daily consumption of 45 g of walnuts, while the other (control period) involved a normal-calorie diet without walnuts. Catalase (CAT) and glutathione peroxidase (GPx) activities, total antioxidant capacity (TAC), and interleukin (IL-1β, IL-6, IL-8) and tumor necrosis factor alpha (TNF-α) levels were determined from serum before and after each intervention period.

RESULTS

Assessment of changes obtained for the selected biomarkers following the walnut and control-diet periods (final-baseline) showed slight changes, but without any statistical significance, among the 20 participants included in the analysis.

CONCLUSIONS

This first RCT targeting a group of middle-aged adults at risk of developing MetS shows that short-term (4 weeks) daily walnut consumption did not significantly alter oxidative stress and inflammation parameters, thus potentially contributing to the maintenance of cellular homeostasis. Further research is needed to investigate the impact of daily walnut consumption over a longer period (>3 months) on oxidative and inflammatory status in the middle-aged population and its potential to positively impact MetS biomarkers.