Jun 17, 2020Study shows heart health benefits for strawberries
Nitrites in strawberries may help the heart health of consumers.
Results from a study funded by the California Strawberry Commission (CSC) suggests a responsive adolescent male population who is at risk for heart disease may benefit from eating a high amount of strawberries for one week.
Results from the study, “Effects of short-term consumption of strawberry powder on select parameters of vascular health in adolescent males” were recently published in the journal Food & Function along with other papers from the 2019 Berry Health Benefits Symposium.
The double-blind randomized control trial was run with 25 males with an average age of 16. While they were healthy with normal blood pressures, cholesterol, and fasting blood glucose levels, they had a higher risk of heart disease due to their body mass index. They were asked to drink either a beverage of 50 grams of strawberry powder mixed with water or a control drink for one week. Lab tests were performed before and after the one-week trial. The teens then switched to the other beverage (strawberry or control) for the second week. The control drink was matched for calories, sugar and fiber.
The berries provide a bunch of beneficial compounds, including dietary fiber, potassium (which is known to be beneficial for blood pressure), Vitamin C and polyphenols that include antioxidants and antioxidant vitamins, said Roberta R. Holt, a scientist at the University of California Davis and one of the authors of the study. But heading into the experiment, researchers were curious about nitrates, which are present in strawberries as well as some leafy greens.
“Strawberries are one of few fruits that provide dietary nitrate, that can be converted in the body to a compound called nitrous oxide that dilates the blood vessels, helps keep your blood vessels healthy,” Holt said.
Holt said the group’s research indicated that the nitrites did provide some health benefits. However, it’s unknown whether they were the primary beneficial nutrient, or make of nutrients in strawberries that help heart health.
Although there were no significant improvements in microvascular function, blood pressure, or cholesterol after an hour or a week, some participants in the study showed a significant increase in total plasma nitrite/nitrate one hour after consuming the strawberry drink, compared to the control drink.
The researchers compared those “responders” who had an increase in the one week change in total plasma nitrate/nitrite after consuming the strawberry powder with those who did not (“nonresponders”). “Responders” did, in fact, have an improvement in vascular function (increase in both reactive hyperemia index and Framingham RHI), while “non-responders” did not.
Funding for the study was provided by the CSC during the 2012-2013 grant cycle. While the CSC doesn’t disclose the funding amounts of individual study grants, Colleen Wysocki, its nutrition communications manager, said that since 2003, the organization has spent more than $6 million on strawberry nutrition research.
Results from the study were recently published in the journal Food & Function. Among the papers was “Effects of short-term consumption of strawberry powder on select parameters of vascular health in adolescent males.”
The commission in April pledged to “harvest every box,” according to an open letter its partners in the food supply chain, which was signed by CSC President Rick Tomlinson and Chairman Hector Gutierrez, who is also a grower. The goal was to keep healthy berries flowing to Americans during the COVID-19 crisis, despite challenges to farm operations and marketing.
“Strawberry farms are committed to protecting farmworker health, maintaining farm jobs and harvesting every box for American consumers,” according to the letter.
CSC maintains a list of recipes at www.californiastrawberries.com for using berries in salads, baked goods, smoothies – a variety of ways to get consumers’ daily diets.
“They have a lot of nutrients that would be great for building up longterm health and immune function,” Wysocki said. “You’re not going to see any acute changes overnight by eating strawberries, but we recommend eating eight strawberries (one serving) a day.”
— Stephen Kloosterman, associate editor