Introduction
Walnuts are the only tree nut that is an excellent source of the plant-based omega-3 alpha-linolenic acid (2.5 grams/oz.), which research shows may play a role in heart health, brain health and healthy aging. Additionally, just one serving of walnuts (1 oz.), or about a handful, contains a variety of other important nutrients to support overall health including 4 grams of protein, 2 grams of fiber, and a good source of magnesium (45 milligrams). Walnuts also offer a variety of antioxidants, including polyphenols. Can eating walnuts, particularly if started earlier in life, have long-term health benefits?
The Study: CARDIA
Few studies have examined long-term associations of walnut, other nut, and no nut consumption with cardiovascular disease (CVD) risk factors. Results from prospective studies with long-term follow-up can provide further evidence for dietary guideline messaging to consume nuts. Therefore, the associations of walnut, other nut, and no nut consumption with diet quality and CVD risk factors over 30 years of follow-up
were examined.
Methods and Results
Data from 3092 young adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Dietary intake, including walnuts and other nuts, was assessed 3 times over 20 years. CVD risk factors were measured at multiple exams.
The 20-year cumulative mean intake of walnuts (0.74 oz/d), other nuts (1.6 oz/d), or no nut consumption was differentially associated with health measures at year 20 and 30 of follow-up.
Generally, walnut consumers had significantly higher health measures, lower body mass index and obeisty, lower waist circumference, lower blood pressure, and lower triglyceride concentrations, and gained less weight since baseline than other nut consumers (p ≤ 0.05 for all). Further, walnut consumers had lower fasting blood glucose than no nut consumers (p ≤ 0.05).
Conclusions
Study findings that walnut and other nut consumption was associated with better CVD risk factors and diet quality aligns with the 2020–2025 US. Dietary Guidelines for Americans recommendation to consume nuts, such as walnuts, within the context of a healthy diet.
According to Professor of Epidemiology and Community Health at the University of Minnesota School of Public Health and Lead Researcher on CARDIA, Lyn M. Steffen, PhD, MPH, RD, "Walnut eaters seem to have a unique body phenotype that carries with it other positive impacts on health like better diet quality, especially when they start eating walnuts from young into middle adulthood – as risk of chronic diseases like heart disease, obesity, and diabetes elevates."
This study is one of the longest to suggest that adding about a handful of walnuts to the diet every day and early on in life could be linked with benefits to overall diet quality as a heart-healthy "carrier food" that fits into any eating occasion.
