The body of evidence about nuts and health continues to grow. These local and international nut research papers, published around February 2021, corroborate decades of research about the importance of a regular handful of nuts in a healthy diet.

Nuts and older adults’ health: A narrative review. (2021).

This review collated the findings from past studies which looked at the effects of nuts on age-related diseases. Specifically, the researchers considered the potential for nut consumption to effect telomere length, sarcopenia, and cognitive function – all major markers for age-related conditions. Based on data to date, they suggest that nut consumption, especially when part of a healthy diet or over a prolonged period, is linked with positive outcomes, such as longer telomere length, reduced risk of sarcopenia and better cognition. But further longer-term intervention studies are needed.

Nut and legume consumption and human health: An umbrella review of observational studies. (2021).

This study reviewed previously-published meta-analyses of observational studies on nut and legume intake and disease, and assessed the level of evidence. Out of the six meta-analyses focussed on legume intake, and 15 on nut intake, a possible association with decreased risk of colorectal adenoma and coronary heart disease was found for higher legume consumption, and a decreased risk of cardiovascular and cancer mortality, colon cancer, hypertension and ischaemic stroke for higher nut consumption.

Effect of green-Mediterranean diet on intrahepatic fat: The DIRECT PLUS randomised controlled trial. (2021).

In this 18-month long trial, 294 adults with abdominal obesity/dyslipidaemia were randomised to one of three weight loss groups: healthy dietary guidelines, Mediterranean Diet (MED), or green-MED. The green-MED had more plant-based proteins/polyphenols (in the form of 3-4 cups/day green tea, and a daily green shake). Both MED groups ate 28g walnuts daily. The green-MED diet, which was also restricted in red/processed meat, doubled intrahepatic fat loss, compared with the other nutritional strategies.

Almond consumption affects faecal microbiota composition, stool pH, and stool moisture in overweight and obese adults with elevated fasting blood glucose: A randomized controlled trial. (2021).

Sixty-nine adults with overweight or obesity and elevated fasting blood glucose were randomised to consume either two serves of almonds a day (56 g/day) or an isocaloric, high-carbohydrate biscuit snack. After eight weeks, the researchers found that daily almond consumption increased the abundance of ruminococci (a potentially-beneficial bacteria) in the fecal microbiota. Fecal short-chain fatty acid levels were unchanged. Further research is needed to assess whether these effects may benefit host health.

A comprehensive study of raw and roasted macadamia nuts: Lipid profile, physicochemical, nutritional, and sensory properties. (2021).

This study, by Chinese-based researchers, compared raw and roasted macadamias. It looked at changes to the chemical composition of lipids (fatty acids, triglycerides, and free fatty acids) and other phytochemicals, and also sensory factors. After roasting, the researchers found only small changes in fatty acid content and a slight decrease in total triglycerides. The total available polyphenol content increased by 25.6% and the oxidative stability index of kernels increased by 21.6%. The sensory scores for taste and aroma were doubled by roasting.

Branched-chain amino acids in relation to food preferences and insulin resistance in obese subjects consuming walnuts: A cross-over, randomized, double-blind, placebo-controlled inpatient physiology study. (2021).

In this crossover, randomized, double-blind, placebo-controlled study, ten adults took part in two 5-day study periods, during which they had a smoothie containing 48g walnuts or a placebo smoothie, without nuts, every morning. A one-month washout period separated the two study phases. Among the outcomes, fasting valine and isoleucine levels were reduced after walnut consumption, and this was linked with HOMA-IR, a marker of insulin resistance. The researchers suggest this may help explain the longer-term benefits of walnuts on insulin resistance, cardiovascular risk and mortality.