People who ate walnuts in young to middle adulthood were more likely to be physically active, eat a higher quality diet and develop a better heart disease risk profile as they got older, a study says. Photo by Ivar Leidus/Wikimedia Commons
Sept. 15 (UPI) -- Walnuts do more than add crunch to banana bread or brownies, according to new research that suggests eating walnuts regularly starting early in life may lead to better health as people age.
Researchers found that participants who ate walnuts in young to middle adulthood were likely to be more physically active, eat a higher quality diet and develop a better heart disease risk profile as they got older.
They said this aligns with the 2020-2025 US. Dietary Guidelines for Americans' recommendation to eat nuts, such as walnuts, as part of a healthy diet.
The new findings appeared Thursday in the journal Nutrition, Metabolism & Cardiovascular Diseases.
For the study, researchers from the University of Minnesota School of Public Health reviewed 20 years of diet history and 30 years of physical and clinical measurements.
The new study, while partly funded by the California Walnut Commission, a state agency established in 1987, is part of broader long-term research: the Coronary Artery Risk Development in Young Adults Study, known as CARDIA.
CARDIA, which is exploring the development of heart disease risk factors over time, is funded by the National Heart, Lung, and Blood Institute at the National Institutes of Health. It began tracking just over 3,000 adults ages 18 to 30 in Birmingham, Ala., Chicago, Minneapolis and Oakland, Calif., in the mid-1980s.
A self-reported diet history was taken three times throughout the study: at baseline, in year seven and year 20. Physical and clinical measurements were taken from multiple exams spanning 30 years.
"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," Lyn M. Steffen, CARDIA's lead researcher said in a news release.
Walnuts "may act as a bridge or 'carrier food' for helping people form healthy nutrition and lifestyle habits throughout life," said Steffen, who is a professor of epidemiology and community health at the University of Minnesota School of Public Health.
Researchers pointed to the walnut's singular characteristics as the only tree nut that is an excellent source of the plant-based omega-3 alpha-linolenic acid (2.5 grams per ounce) that previous research suggests may play a role in heart health, brain health and healthy aging. Flaxseed also is a good source of this type of omega-3 fatty acid.
The investigators noted that a 1-ounce serving of walnuts, or about a handful, has other healthy nutrients, including 4 grams of protein, 2 grams of fiber and 45 milligrams of magnesium. And, they said, walnuts contain various antioxidants, including polyphenols.
The researchers said they looked for relationships among heart disease risk factors, including dietary intake, smoking, body composition, blood pressure, plasma lipids, fasting blood glucose and insulin concentrations in 352 walnut consumers, 2,494 "other nut" consumers and 177 people who didn't eat nuts.
During the study, the walnut eaters had about three-quarters of an ounce daily, while other nut consumers ate about 1.5 oz. a day.
After 30 years, the walnut consumers had higher self-reported physical activity scores than people in the "other nut" and "no nut" categories. They also had a better heart disease risk profile, with lower body mass index, waist circumference, blood pressure and blood triglyceride levels.
The walnut eaters also gained less weight over the study period, and fewer of them were classified as obese, as compared to people in the other categories, the study said.