The body of evidence about nuts and health continues to grow. These local and international research papers, published around February 2023, corroborate decades of research about the importance of a regular handful of nuts within a healthy diet.

Nuts and seeds consumption and risk of cardiovascular disease, type 2 diabetes and their risk factors: A systematic review and meta-analysis. (Arnesen et al, 2023)
This systematic review included 42 papers from cohort studies (28 unique cohorts, 1,890,573 participants) and 18 (≥12-week) randomized controlled trials (2,266 participants). Among the findings, consumption of total nuts/seeds was associated with lower risk of CVD and CHD, in a dose dependent manner. Smaller or unclear associations were found for risk of stroke and type 2 diabetes. Nuts modestly lowered blood lipids (total and LDL-cholesterol), but had no effect on blood pressure in randomized controlled trials. The reviewers say the favourable associations with CVD and CHD are probably causal.

Effects of nut consumption on blood lipids and lipoproteins: A comprehensive literature update. (Guasch-Ferré et al, 2023)
This comprehensive narrative overview, of 19 systematic reviews and meta-analyses of randomised controlled trials, outlines current knowledge on the effects of nuts on blood lipids and lipoproteins. Among the findings was a consistent beneficial effect of most nuts (total nuts and specific nut types, including walnuts, almonds, cashews, peanuts, and pistachios), across meta-analyses in reducing total cholesterol (mean difference: −0.09 to −0.28 mmol/L), LDL-cholesterol (mean difference: −0.09 to −0.26 mmol/L), and triglycerides (mean difference: −0.05 to −0.17 mmol/L).

Nuts in the prevention and management of type 2 diabetes. (Nishi et al, 2023)
This review looked at the epidemiological and clinical evidence to date for the role of nut consumption in preventing and managing type 2 diabetes, and its related complications. Overall, the findings suggest higher nut consumption may have beneficial effects, with mechanistic studies assessing nuts and individual nut-related components, supporting this possibility. However, the authors conclude that limited definitive evidence is available to date, and future studies are needed on the role of nuts in diabetes prevention and management.

Impact of nut consumption on cognition across the lifespan. (Nishi et al, 2023)
This narrative review outlines the epidemiological, clinical trial, and mechanistic evidence of the effect of exposure to nuts on cognitive performance. It found that the available evidence suggests a possible role for nuts in the maintenance of cognitive health and prevention of cognitive decline across the lifespan, particularly in older adults and those at higher risk. Walnuts, as a rich source of the plant-based polyunsaturated omega-3 fatty acid alpha-linolenic acid, are the nut type most promising for cognitive health. The authors conclude that future studies are needed in this area.

Mixed nuts as healthy snacks: Effect on tryptophan metabolism and cardiovascular risk factors. (Yang et al, 2023)  
This study examined the effect of mixed tree nuts on tryptophan metabolism, and the link to cardiovascular risk markers. Study participants (95 overweight people) were given either 42g/day of mixed tree nuts, or an isocaloric pretzel control. for 12 weeks, as part of a weight loss diet. This was followed by a weight maintenance program for another 12 weeks. Daily nut consumption led to improved tryptophan metabolism and higher serotonin levels, compared with the control – providing insights into the possible mechanisms behind the heart health benefits of nuts.

Olive oil and nuts in rheumatoid arthritis disease activity. (De Vito et al, 2023)
Within a recent Italian cross-sectional study (365 people, with a median age of 58 years, and 78% females), researchers investigated the link between two single food groups (olive oil and nuts) and disease activity in rheumatoid arthritis (RA). They found higher consumption of both foods had a favorable effect on disease activity, significant only for olive oil. This favorable effect was stronger in the more severe or long-standing forms of RA. They say these results need confirmation with additional well-designed cohort studies.

Pecan-enriched diet improves cholesterol profiles and enhances postprandial microvascular reactivity in older adults. (Cogan et al, 2023)
In this randomised control study, 44 older adults (59 ± 6 years) consumed 68g of pecans/day, or avoided all nuts (control group) over four weeks. Daily pecan consumption resulted in greater reductions in fasting total cholesterol, LDL-cholesterol, non–HDL cholesterol, LDL particle number, and LDL medium, compared with control. Post-prandial triglycerides were also suppressed in the pecan group. The researchers concluded that long-term pecan consumption may improve vascular health and reduce risk for cardiovascular events.

Particle size distribution and predicted lipid bioaccessibility of almonds and the effect of almond processing: A randomised mastication study in healthy adults. (Creedon et al, 2023)
This randomised cross-over study, involving 31 healthy adults, looked at the impact of processing almonds (grinding them into flour), on particle size distribution (PSD) and predicted lipid bioaccessibility following mastication. After chewing, commercially-ground almonds had a PSD with significantly fewer larger particles and more smaller particles, compared with whole almonds. And this results in a modest (but statically significantly) increase in predicted lipid bioaccessibility.

Effect of almond consumption on insulin sensitivity and serum lipids among Asian Indian adults with overweight and obesity– A randomized controlled trial. (Gayathri et al, 2023)
This parallel-arm, randomised controlled trial, conducted in India, involved 352 participants (aged 25–65 years, with a BMI ≥ 23 kg/m²). The intervention group received 43g of almonds/day for 12 weeks, while the control group ate a customary diet but avoided nuts. Daily consumption of almonds increased the intake of mono-unsaturated fatty acids (with a decrease in carbohydrate calories). The almond group had significant improvements in insulin resistance, insulin sensitivity and serum cholesterol, compared with the control group. The researchers concluded that this could help reduce the risk of diabetes and other cardiometabolic diseases, in Asian Indians with overweight/obesity.

Analysis of the antioxidant activity, lipid profile, and minerals of the skin and seed of hazelnuts (Corylus avellana L.), pistachios (Pistacia vera) and almonds (Prunus dulcis) – A comparative analysis. (Mohammed et al. 2023)
The aim of this research was to evaluate the total antioxidant activity (by ferric reducing antioxidant power assay), fatty acids (by acid-catalyzed esterification method), and minerals (by inductively coupled plasma optical emission spectrometer) in the seeds and skins of hazelnuts, pistachios, and almond. The study concludes that hazelnut, pistachio, and almond skins are a great source of antioxidants, minerals (including manganese, zinc, iron, copper and selenium – depending on the nut), and healthy fatty acids, making them useful for nutraceutical development.

Association between protein intake from different animal and plant origins and the risk of non-alcoholic fatty liver disease: A case-control study. (Khazaei et al, 2023)
This case-control study looked into the association between the consumption of total protein, and different sources of protein, and non-alcoholic fatty liver disease (NAFLD) risk. It included 121 incidence cases of NAFLD, and 122 healthy controls. Higher intake of protein was significantly associated with a lower risk of NAFLD. And a higher tendency to plants, grains, and nuts as the main sources of protein, were correlated with lower NAFLD risk. The authors conclude that increasing the consumption of proteins, particularly from plants, may be a good recommendation to manage and prevent NAFLD.

Eat for better cognition in older adults at risk for Alzheimer’s disease. (Wang et al, 2023)
This review summarises the role of diet, nutrient supplementation, and microbioecologics in cognitive decline. It found that interventions, such as modified Mediterranean-ketogenic diet, nuts, vitamin B, and Bifidobacterium breve A1, are beneficial to cognition protection. The authors say the stages of preclinical Alzheimer’s disease are thought to be a better intervention period. They conclude that eating, rather than just taking medicine, is suggested to be an effective treatment method for older adults at risk for Alzheimer’s disease.