Source: Science Daily
You might want to rethink that banana-blueberry smoothie. While bananas are considered among the healthiest fruits on the planet—packed with essential nutrients, dietary fiber, and minerals—a new study suggests they may be undermining berry-based smoothies and significantly reducing the body's ability to absorb flavanols, plant compounds linked to heart and brain health.
It all has to do with how fruit ingredients interact when blended, according to findings published in Food & Function by researchers at the University of California, Davis. While bananas and berries are both nutrient-rich and highly beneficial on their own, the researchers found that fruits high in an enzyme called polyphenol oxidase (PPO), which is abundant in bananas, can interfere with flavanol absorption. Flavanols are naturally occurring compounds found in foods such as blueberries, grapes, apples, and cocoa, and are associated with various potential health benefits, including improved cardiovascular health and cognitive function.
They further noted that the same enzyme responsible for browning in cut or bruised fruit, while harmless on its own, appears to reduce the availability of flavanols in the body when present in a smoothie.
The study compared blood and urine samples from participants who consumed a banana-based smoothie, a mixed berry smoothie, and a flavanol capsule as a control. The results showed that those who drank the banana smoothie had up to 84% lower flavanol levels compared with the control group. In contrast, the berry-based smoothie produced flavanol levels similar to those seen with the capsule.
"We were really surprised to see how quickly adding a single banana decreased flavanol levels in both the smoothie and the body," researchers noted, adding that fruit combinations can trigger chemical interactions that may influence the absorption of certain nutrients.
A follow-up test further found that even when the ingredients were not blended together beforehand, the presence of PPO after consumption could still produce the same effect.
Their recommendation? To fully benefit from the nutrients in bananas—such as potassium, fiber, and vitamin B6—it is best to avoid pairing them with flavanol-rich ingredients like berries, cocoa, or grapes.
Nutrition experts generally recommend a daily intake of around 400 to 600 milligrams of flavanols for cardiometabolic health, typically obtained from foods such as tea, apples, berries, grapes, and cocoa. If you still want a more varied and flavorful smoothie, you can pair flavanol-rich ingredients with foods lower in PPO activity, such as pineapple, oranges, mango, or yogurt.
Bananas and berries are both good for the body, but they may be best enjoyed separately. Simply forgo one or the other, sacrificing the added sweetness and creaminess they bring to the blend. While nothing catastrophic will happen, the practical takeaway remains: what you mix together in a blender may affect what your body actually absorbs.
