The body of evidence about nuts and health continues to grow. These local and international research papers, published around March 2024, corroborate decades of research about the importance of a regular handful of nuts within a healthy diet.

Nut consumption during pregnancy is associated with decreased risk of peer problems in 5-year-old Japanese children. (Nguyen et al, 2024).
This study analysed data from the Kyushu Okinawa Maternal and Child Health Study (KOMCHS) – a pre-birth cohort study in Japan. Study subjects were 1,199 mother–child pairs. After adjustment for potential non-dietary and dietary confounding factors, it found that maternal consumption of nuts during pregnancy was linked with a significantly reduced risk of peer problems in 5-year-old children. Further research is needed in this area, including on the mechanisms underlying the preventive association seen in this study.

Association between self-perception of aging and long-term mortality in elderly patients with hypertension in rural China: A possible beneficial effect of nut intake. (Lu et al, 2024).
In this observational study, poorer self-perception of aging (SPA) was associated with a high risk of mortality in rural elderly (60+ years of age) Chinese people with hypertension. Healthy lifestyle habits and behaviours (including weekly nut intake, BMI management, and regular blood pressure monitoring) were also linked with a lower risk of death. In subgroup analysis, for those 75 years or older, weekly nut intake might have a moderating role in the relationship between SPA and mortality, potentially due to impacts on cognition and mood.

Brazil nut consumption reduces DNA damage in overweight type 2 diabetes mellitus patients. (Macan et al, 2024).
This trial assessed the effect of selenium consumption, through Brazil nuts, on biochemical and oxidative stress parameters, and genomic instability. It involved 74 study participants, with type 2 diabetes. Participants consumed one Brazil nut a day for six months. This resulted in improved blood lipid profiles, increased antioxidant activity, and reduced oxidative damage to proteins, lipids, and DNA molecules, suggesting a role for Brazil nuts in reducing oxidative stress and modulating genomic instability (DNA changes) in people with type 2 diabetes.

Walnut consumption improves sleep quality: A randomized-controlled trial. (Izquierdo-Pulido et al, 2024).
In this randomised cross-over trial, 80 healthy young adults either ate 40g of walnuts daily, or had no walnuts, or any other nuts, (control) for 8 weeks, with a washout period of 2 weeks. It found walnut consumption was significantly associated with improved sleep quality (lower sleep latency, higher sleep efficiency, and less day time sleepiness). The melatonin metabolite, 6-sulfatoxymelatonin, was also significantly higher with walnut consumption. This suggests that a daily serving of 40g of walnuts increases melatonin, which can improve sleep quality and reduce daytime sleepiness. 

Walnut consumption reduces perceived stress and improves mood states in a sample of young adults: A randomized cross-over trial. (Zerón-Rugerio et al, 2024).
This randomised-cross over trial, involving 30 young adults (aged 24.0 ± 4.2 years; 90% women), found daily consumption of 40g of walnuts for 8 weeks significantly reduced perceived stress and improved certain mood states, such as anger–hostility and fatigue–inertia, compared with control. Also, daily walnut consumption has a significant impact on serotonin levels, suggesting this may be an underlying mechanism behind the improved mood and stress states seen with walnut consumption.

Peanuts supplementation affects compositions and functions of gut microbiome in Ugandan children. (Wang et al, 2024).
This trial involved 120 Ugandan children, aged 6-9 years. Half received daily roasted peanut snacks (57g peanuts), while the other half did not (control group). Faecal samples were collected at baseline, day 60, and day 90. Significant differences were seen between the control and peanut-supplemented groups after 90 days, indicating a role for peanuts in modulating the gut metabolome, enriching beneficial bacteria, and inhibiting pathogens. In turn, the authors suggest this may offer a novel approach to mitigating child malnutrition and improving health status.

Dietary intake of plant- and animal-derived protein and incident cardiovascular diseases: The pan-European EPIC-CVD case-cohort study. (Zheng et al, 2024).
This case-cohort study investigated the associations of plant- and animal-derived protein intake with risk of total CVD, plus CAD and stroke. It included 16,244 CVD cases (10,784 CAD and 6,423 stroke) and 15,141 sub-cohort participants, from seven European countries. Overall, there was no association between plant-derived or animal-derived protein intake with total CVD or with CAD or stroke incidence, but the replacement of protein from red meat, processed meat or dairy with plant-derived protein might be associated with a lower risk of fatal stroke.

Association between Mediterranean diet and dementia and Alzheimer disease: A systematic review with meta-analysis. (Nucci et al, 2024).
This systematic review with meta-analysis assessed the association between adherence to the Mediterranean diet (MedDiet) and risk of dementia in older people (60+ years of age). The systematic review included 21 previously-published studies. Overall, it found a protective effect with higher adherence to the MedDiet. Specifically, there was an 11% reduction in the likelihood of developing dementia (based on a total study population of 65,955 older adults), and a 27% reduction if only Alzheimer’s disease was considered (based on 38,292 total participants).

Effect of 1-year lifestyle intervention with energy-reduced Mediterranean diet and physical activity promotion on the gut metabolome and microbiota: A randomized clinical trial. (Garcia- Gavilan et al, 2024).
This intervention study, involving 400 participants, found that an energy-reduced MedDiet and physical activity promotion, compared with an ad libitum MedDiet, produced significant changes in gut metabolomics and microbiota in a Mediterranean population of older adults (aged 55-75 years) with overweight/obesity and metabolic syndrome. And these changes, in faecal metabolites and faecal microbiota, were associated with changes in several cardiometabolic risk factors, including a greater reduction in adiposity and improvements in lipid profile and markers of glucose metabolism.

Mediterranean diet adherence and health-related quality of life during pregnancy: Is the Mediterranean diet beneficial in non-Mediterranean countries? (Flor-Alemany et al, 2024).
This study examined the association of MedDiet adherence and MedDiet components with health-related quality of life in 138 pregnant women from Spain and 302 from Sweden. Among the findings, greater MedDiet adherence throughout gestation was associated with lower pain during pregnancy, in both Mediterranean and non-Mediterranean populations. Specifically, a greater intake of fibre, fish, fruits, nuts, and legumes seemed to explain these associations.