Elderly people who added walnuts to their diet had higher levels of several nutrients
A new study published in Nutrients explored how dietary supplementation with walnuts affected polyphenol intake and the urinary excretion of phenolic metabolites in elderly participants. It was the first study to show that the addition of a single food (i.e. walnuts), with no other changes to the usual diet, could significantly increase total polyphenol intake. Polyphenols are nutrients that have been associated with various health benefits, including decreased blood lipids and inflammatory markers.
The study was a secondary data analysis of Walnuts and Healthy Aging (WAHA), a two-year parallel-group, observer-blinded randomized controlled trial examining how dietary supplementation with walnuts at 15% of daily energy intake (30–60 g/d) compared to a walnut-free habitual diet affected aging outcomes in free-living elderly participants. The secondary analysis included a total of 300 men and women aged 63 to 79 years.
As compared to the control group, participants in the walnut group had a significantly higher mean daily intake of total polyphenols, flavonoids, flavanols and phenolic acids. There was a significant inverse association between dietary flavonoid intake and urinary excretion of polyphenols; reduced urinary excretion may imply that some polyphenols were eliminated via the gut, an effect likely to have a favorable impact on the intestinal microbiome. Nuts had a significant contribution to total dietary polyphenols, suggesting that the inclusion of a single food like walnuts in a habitual diet can increase polyphenol intake.
This study was funded by the California Walnut Commission.
Amen, R. I., Sirirat, R., Oda, K., Rajaram, S., Nwachukwu, I., Cofan, M., Ros, E., et al. (2023). Effect of Walnut Supplementation on Dietary Polyphenol Intake and Urinary Polyphenol Excretion in the Walnuts and Healthy Aging Study. Nutrients, 15(5), 1253. MDPI AG.