Several studies have shown that nut supplementation improves cognitive function in young and old adults. In addition, tree nut consumption has also been linked to changes in the gut microbiota.
However, there are no studies to simultaneously assess the effects of nuts on cognition and intestinal microbial communities.
Despite the high-calorie and fat content of nuts, they contain mono- and polyunsaturated fats, which can positively affect your health.
Eating nuts regularly can lower your cholesterol levels and relax your blood vessels, both of which can strengthen your heart. In addition, it turns out that nuts can also be good for cognitive health – going nutty for nuts can improve your brain’s health.
The study examined cognitive performance (primary outcome), mood, metabolomics, and gut microbial species in healthy, non-elderly adults who consumed tree nuts daily for four weeks.
In this study, participants were given 30 grams of mixed tree nuts (15 grams walnuts, 7.5 grams almonds, 7.5 grams hazelnuts) and a placebo (microcrystalline cellulose) for 28 days each, followed by a 4-week washout period.
A lack of association between nut consumption and cognitive decline in older adults suggests early nutritional intervention is necessary. This is to ensure a positive impact on cognitive decline in older age. Therefore, researchers examined the effect of mixed tree nut supplementation on the mental and mood function of 18 – 49-year-olds.
To determine whether nut consumption impacts metabolic responses and gut microbiota colonization, Researchers employed a multi-omic approach to determine whether these factors affect cognition. This first intervention study incorporates cognitive, metabolic, and gut microbiota responses to whole foods.
An Australian study also found that older adults who ate nuts had higher cognitive scores than those who did not. In addition, people who ate nuts moderately, equivalent to 15-30g per day, scored higher on cognitive tests. The study included 1,814 people 60 years and older, taken from the National Health and Nutrition Examination Surveys (NHANES) 2011-2012 and 2013-2014 cohorts.
This Australian study also measured cognitive function, including immediate and delayed recall, verbal fluency, and processing speed and attention.
In contrast to the moderate-intake group, eating more than 30 grams daily did not improve cognitive performance. In delayed recall, a significantly higher score was seen when the nut intake was greater than 30 grams daily. Nut consumption was associated with better diet quality and higher nutrient intakes.
According to mixed model analysis, nutrient consumption significantly improved accuracy and response speed on a picture recognition task. However, no significant changes in bacterial communities’ alpha or beta diversity were observed compared to placebo consumption.
However, supplementation with nuts significantly enhanced the abundance of an unclassified Lachnospiraceae amplicon sequence variant (ASV). The changes in picture recognition did not correlate with changes in the unclassified Lachnospiraceae ASV, and the urinary metabolome did not change significantly.
Researchers found that nut consumption positively affected cognition in a healthy, non-elderly sample after four weeks and upregulating gut-associated microbial taxa. While the effects appear independent, further investigation is needed in individuals with cognitive decline or gut dysbiosis.