A study carried out by researchers from the TH Chan School of Public Health, Harvard University ( United States ) has shown that a higher consumption of walnuts , both in quantity and frequency, is associated with a lower risk of death and an increase of life expectancy among older adults, as published in the journal Nutrients .
“What we have learned from this study is that even a few handfuls of walnuts a week can help promote longevity , especially among those whose diet quality is not great to begin with. This is practical advice that may be doable. for a large number of people who seek to improve their health, which is the most important thing for many people, “says Yanping Li, Principal Research Scientist in the Department of Nutrition at the Harvard TH Chan School of Public Health, and principal investigator of this research .
This study, supported by the California Nut Commission, found that five or more servings of walnuts per week (one serving = 30 grams) may provide the greatest benefit for mortality risk and life expectancy. Thirty grams of walnuts are a source of important nutrients for optimal health, including protein (4g), fiber (2g), a good source of magnesium (45mg) and an excellent source of the essential omega-3 ALA (2.5g).
Consuming five or more servings per week was associated with a 14% lower risk of death (from any cause), a 25% lower risk of dying from cardiovascular disease, and a gain of approximately 1.3 years of life expectancy. life, compared to those who did not consume nuts.
Consuming walnuts two to four times a week could also have its benefits , as the study found a 13% lower risk of death overall, a 14% lower risk of dying from cardiovascular disease, and a gain of about a year in life, compared to those who did not consume nuts.
Interestingly, even among people on a suboptimal diet, as measured by a validated index based on foods and nutrients that predict chronic disease risk, only a half-serving-a-day increase in nut consumption was associated with benefits, including a 12 % less risk of death and 26% less risk of death from cardiovascular diseases, specifically.
For this study, the researchers examined data from 67,014 women from the Nurses Health Study with a mean age of 63.6 years and 26,326 men from the Health Professionals Follow-up Study with an age of 63.3 years in 1986 (the first cycle data collection on walnut consumption in both cohorts).
Participants were relatively healthy when they joined the studies (for example, free from cancer, heart disease, and stroke) and were followed for about 20 years (1998-2018).
Dietary intake was assessed every four years , in which participants reported their overall dietary intake – including how often they consumed nuts, other tree nuts, and peanuts – as well as lifestyle factors such as exercise and habit of smoking. From these data, the researchers were able to identify associations between nut consumption at different levels and different health indicators related to longevity.
As a prospective observational study, these results do not demonstrate a cause-effect relationship , but they do shed light on how walnuts can contribute to an overall healthy lifestyle that promotes longevity.
Participants who ate higher amounts of nuts tended to be more physically active , eat a healthier diet, consume less alcohol, and take multivitamins. All of these factors could influence life expectancy; however, the researchers adjusted for these in their analysis.