The epidemiological study, published in the Journal of Aging Research, defined healthy ageing as "longevity with sound mental health and no major chronic diseases, cognitive issues or physical impairments” after the age of 65.
Primary investigator Dr. Francine Grodstein looked at data from 33,931 women in the Nurses' Health Study (NHS) to evaluate the association between nut consumption and overall health and well-being in aging.
Between 1998-2002, female nurses in the NHS were asked about their diet, including total nut consumption. They were then evaluated for chronic diseases such as cancer, heart attack, heart failure, stroke, type 2 diabetes and Parkinson's disease. Participants were also assessed for memory concerns, mental health and physical limitations including daily activities.
Of the study participants, 16% were found to be ‘healthy agers’ with the remainder classified as ‘usual agers’.
“When we examined the relation of nut consumption at midlife and subsequent odds of healthy aging, we observed a significant association between total nut intake and higher odds of healthy aging,” the researchers noted.
The study also included nut type – looking specifically at consumption of peanuts, peanut butter, walnuts and other nuts.
When researchers stripped out various factors that could impact health in older adults, from education to physical activity levels, they noted walnuts were ‘the only nuts’ associated with ‘significantly better odds’ of healthy ageing.
The authors concluded: “We found statistically significantly better odds of healthy aging across peanuts, walnuts and other nuts. After control for all potential confounding factors, especially overall diet quality, all results were attenuated. Walnut consumption alone remained associated with statistically significantly better odds of healthy aging.”
The researchers, who were supported by the California Walnut Commission, noted the growing importance of finding low-cost early interventions like healthy food choices to support the health of the ageing population.
“We found that consumption of nuts at midlife was related to a greater likelihood of overall health and well-being at older ages. The association was particularly robust for walnuts, a source of alpha-linolenic acid and ellagitannins.
“Since many health conditions of aging develop over decades and, thus, earlier lifestyle factors likely have the most influence on later health, our results support the notion that long-term consumption of nuts, a fairly low-cost dietary intervention, merits further confirmation as a strategy contributing to healthier lifespan.”
The research builds on prior work connecting healthy diets – including nuts – to improved physical and cognitive health in later life. Nevertheless, the research team noted some limitations to the observational study, which was based on reported dietary intake, in that it only looked at outcomes for women and does not prove cause and effect.
‘Consumption of Nuts at Midlife and Healthy Aging in Women’
Journal of Aging Research
Authors: Tania-Marisa Freitas-Simoes, Maude Wagner, Cecilia Samieri, Aleix Sala-Vila and Francine Grodstein