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

Intake of nuts or nut products does not lead to weight gain, independent of dietary substitution instructions: A systematic review and meta-analysis of randomized trials. (2020).

This analysis found that nuts may be consumed, even in large amounts, without changes in body weight (BW) or body composition. The researchers looked at 55 nut feeding trials, involving more than 3,800 adults. Some of the studies included substitution instructions (for example, guidance on what to remove from the diet to compensate for adding nuts in) and some did not. They concluded that nut consumption does not result in changes in BW, body mass index or waist circumference in studies with or without substitution instructions.

Metabolic syndrome features and excess weight were inversely associated with nut consumption after 1-year follow-up in the PREDIMED-Plus Study. (2020).

The aim of this study was to assess whether changes in nut consumption over a one-year follow-up were associated with changes in features of metabolic syndrome in a middle-aged and older Spanish population at high cardiovascular disease risk. It found that features of metabolic syndrome and excess weight were inversely associated with nut consumption after one-year follow-up. As nut consumption increased, between each tertile, there was a significant decrease in waist circumference, triglycerides, systolic blood pressure, weight, and BMI, and a significant increase in HDL cholesterol in women.

Replacing the consumption of red meat with other major dietary protein sources and risk of type 2 diabetes mellitus: A prospective cohort study. (2020).

Pooled analyses from well-known, large prospective studies (the Health Professionals Follow-up Study, Nurses’ Health Study and Nurses’ Health Study II) found that a decrease in intake of red meat during a four-year period, together with an increase in another major protein food, was associated with a lower risk of type 2 diabetes in the subsequent four-year period. The hazards ratio per one serving/day was 0.83 for nuts, 0.82 for poultry, 0.87 for seafood, 0.82 for low-fat dairy, 0.82 for high-fat dairy, 0.90 for eggs, and 0.89 for legumes. The associations were present for both unprocessed and processed red meat, although stronger for the replacement of processed red meat.

Identifying usual food choice combinations with walnuts: Analysis of a 2005-2015 clinical trial cohort of overweight and obese adults. (2020).

This study, by Australian-based researchers, explored usual food intake data from four food-based clinical trials, involving a total of 758 overweight or obese adults. They assessed how food choices were associated with walnut intake at different meal occasions. The study suggests that walnuts were more likely to be consumed at small meals, such as midmeals or snacks. There were no identified patterns to food choices in relation to walnuts at the breakfast, lunch, or dinner meal.

Effect of chronic consumption of nuts on oxidative stress: A systematic review of clinical trials. (2020).

This systematic review of 16 clinical trials looked into the impact of nut consumption on oxidative stress and the possible mechanisms involved. Nut doses were generally high (> 30g/day), follow-up ranged from four weeks and six months, and oxidised low-density lipoprotein (ox-LDL) was the most assessed biomarker. Nut consumption appeared to be effective in changing some oxidative stress biomarkers. But the study authors said further research is needed because the benefits depend on nut type, nut dose, and population characteristics. No studies reported harmful effects of nut consumption, even in high doses.

One-year dietary supplementation with walnuts modifies exosomal miRNA in elderly subjects. (2020).

This research took a deep-dive into the mechanisms of how nuts may lower the risk of certain diseases. They randomised healthy elderly subjects to either a control group (abstaining from walnuts) or a group who received a daily portion of walnuts that contributed 15% of their total energy (around 30–60 g/day) for one year. They found that eating walnuts consistently modulated circulating microRNAs – molecules involved in the regulation of gene expression, which play a key role in health and disease. More research is needed in this emerging area.

The effect of adherence to the Mediterranean diet on late-life cognitive disorders: A systematic review. (2020).

This systematic review, which included 45 studies, found a protective effect of the Mediterranean Diet on late-life cognitive decline. The researchers state that further intervention studies are needed to confirm the efficacy of the Mediterranean Diet in preventing cognitive disorders. But based on their results, they concluded that this dietary pattern should be considered part of a multi-pronged approach to improving late-life cognitive function.