Researchers at the University of California, Davis, have discovered that incorporating bananas into berry smoothies can significantly diminish the drink’s health benefits. Their findings, published in the journal Food & Function, indicate that the combination of certain ingredients impairs the absorption of flavanols – natural antioxidants linked to the protection of the cardiovascular system, blood vessels, and the brain.
During their investigation, the specialists examined various combinations of blended fruits and their impact on flavanol bioavailability. Experiments demonstrated that the presence of even a single banana in a smoothie reduces the absorption of these compounds by approximately 84 percent. The scientists attribute this effect to the enzyme polyphenol oxidase, which is responsible for the browning of fruits after they are cut.
When a banana is pulverized in a blender, its cellular structures break down, leading to the release of a substantial amount of the active enzyme. Polyphenol oxidase then reacts with the flavanols found in berries, grapes, and cocoa. This interaction degrades the structure of these beneficial substances, resulting in a much lower amount being available for the body to absorb.
To substantiate their hypothesis, the scientists conducted a clinical trial involving healthy volunteers. Participants were given three options: a capsule containing pure flavanols, a berry smoothie with low polyphenol oxidase content, and a berry-banana smoothie. Subsequently, the researchers assessed the flavanol levels in the subjects’ bodies through blood and urine tests.
The results revealed that individuals who consumed the banana-berry beverage showed no significant increase in flavanol levels compared to their baseline measurements. Conversely, the berry smoothie without banana demonstrated substantially higher antioxidant bioavailability.
In a subsequent phase of the study, the specialists determined that the degradation of beneficial compounds persists even when bananas and berries are consumed separately with a short time interval between them. This suggests that the activity of polyphenol oxidase remains potent even within the acidic environment of the stomach.
The study’s authors emphasize that bananas themselves remain a nutritious food. They contain potassium, fiber, and serve as an energy source, so there is no need to exclude them from the diet. However, to maximize the intake of antioxidants, the specialists advise against combining bananas with berries, grapes, and cocoa in the same dish or beverage.
As an alternative for achieving a thick texture and sweet taste in smoothies, nutritionists suggest using pineapples, mangoes, oranges, or yogurt. The researchers believe that a more deliberate selection of ingredients can contribute to enhancing the nutritional value of one’s daily diet.
About the Author
