Credit: Pixabay/CC0 Public Domain
Credit: Pixabay/CC0 Public Domain
Smoothies can be a delicious and convenient way to get the important fruits and vegetables you need for a healthy diet. But is a banana and blueberry smoothie the best combination? Researchers at the University of California, Davis, suggest that blending certain ingredients into smoothies can affect whether your body gets a nutritional boost.
The study published today in Food and jobThe researchers used the juices to test how different levels of polyphenol oxidase, an enzyme found in many fruits and vegetables, affected the levels of flavanols in food that were absorbed by the body. Flavanols are a group of bioactive compounds that are beneficial for your heart and cognitive health and are found naturally in apples, pears, blueberries, blackberries, grapes and cocoa – popular juice ingredients.
“We sought to understand, on a very practical level, how a common food and food preparation such as banana juice might affect the availability of flavanols that can be absorbed after ingestion,” said lead author Javier Ottaviani, director of the UCLA Core Laboratory. Mars Edge, part of Mars, Inc., is a research assistant in the Department of Nutrition at the University of California, Davis.
Slice an apple or banana peel and the fruit will quickly turn brown. This is caused by polyphenol oxidase, or PPO, an enzyme naturally found in those foods. Browning occurs when food containing this enzyme is exposed to air or is cut or bruised. The researchers wanted to know if consuming freshly squeezed juices made from various fruits that contain PPO affects the amount of flavanols available to the body.
Banana vs. berries
The researchers asked the participants to drink a juice made from bananas, which have naturally high PPO activity, and a juice made from mixed berries, which have naturally low PPO activity. Participants also took a flavanol capsule as a control. Blood and urine samples were analyzed to measure the level of flavanols present in the body after consuming juice and capsule samples. The researchers found that those who drank banana juice had 84% lower levels of flavanols in their bodies compared to the control group.
“We were really surprised at how quickly adding one banana lowered the level of flavanols in the juice and the levels of flavanols that were absorbed by the body,” Ottaviani said. “This highlights how food preparation and formulations affect the absorption of nutrient compounds in foods.”
Last year, the Academy of Nutrition and Dietetics issued a dietary recommendation advising people to consume 400 to 600 milligrams of flavanols daily for heart and metabolic health. For people trying to consume these flavanols, Ottaviani said, they should consider preparing smoothies by combining flavanol-rich fruits like berries with other ingredients that also have low PPO activity such as pineapple, orange, mango, or yogurt.
He also said that bananas remain a great fruit to eat or have in smoothies. For those who want to eat their smoothies with bananas, or other high-PPO fruits and vegetables like beet greens, the suggestion is not to combine them with flavanol-rich fruits like berries, grapes, and cocoa.
The results of this study could spur future research on how other foods are prepared and the effects on flavanols. For example, Ottaviani said tea is a major dietary source of flavanols and depending on how it is prepared, a different amount of flavanols will be available. to absorb.
“This is definitely an area that deserves more attention in the area of polyphenols and bioactive compounds in general,” Ottaviani said.
Additional research was contributed by Judy Ensonsa, Redmond Fong, Jennifer Kimball, and Alan Crozier, all affiliated with the UC Davis Department of Nutrition and researchers affiliated with UC Davis Department of Internal Medicine, University of Reading, King Saud University, and Mars.
Javier I. Ottaviani et al, Effect of polyphenol oxidases on the bioavailability of flavan-3-ols in fruit juices: a single-blind, controlled, cross-over study, Food and job (2023). doi: 10.1039/D3FO01599H