Smoothies rank among the most popular healthy beverages worldwide. Many people prepare them at home because they’re quick, flavorful, and a simple way to boost fruit intake.
Typically, a smoothie recipe features bananas, berries, yogurt, and other nutritious components blended into a creamy drink.
Recently, researchers from the University of California, Davis, uncovered that one common smoothie ingredient might quietly lower the amount of beneficial plant compounds your body can absorb.
The study, published in the journal Food & Function of the Royal Society of Chemistry, revealed that bananas could interfere with the body’s ability to absorb flavanols, vital natural substances associated with cardiovascular and brain health.
Flavanols are plant-derived nutrients found abundantly in fruits like berries, grapes, apples, and in foods such as cocoa, pears, and tea. Scientists have long explored their potential to enhance blood circulation, support healthy blood pressure, and protect brain and heart functions.
Health authorities like the Academy of Nutrition and Dietetics recommend that adults aim for about 400 to 600 milligrams of flavanols daily for metabolic health. Many try to increase their intake through berries or smoothies rich in antioxidants.
The issue isn’t with the berries themselves; rather, it’s about interactions that happen when different foods are blended together.
The scientists focused on an enzyme called polyphenol oxidase (PPO), naturally present in many fruits and vegetables. PPO is responsible for the browning seen after cutting an apple or peeling a banana.
Once exposed to air, PPO reacts with plant compounds, causing browning.
Bananas, which have high PPO activity, prompted researchers to investigate whether this enzyme might also impact flavanols within smoothies.
To explore this, they created smoothies with fruits that had varying levels of PPO. Bananas represented high-PPO ingredients, while mixed berries served as low-PPO options.
Participants consumed three different formulations: a banana smoothie, a mixed berry smoothie, and a flavanol capsule as a baseline. Blood and urine samples were then analyzed to measure flavanol absorption.
The findings were striking. Those who drank the banana smoothie had flavanol levels 84% lower than the control group. Conversely, berry smoothies without bananas showed flavanol levels similar to the capsule, indicating better absorption.
Lead researcher Javier Ottaviani noted his surprise at how much a single banana could diminish flavanol availability. The results suggest that food combinations and how they’re prepared can significantly affect nutrient absorption.
Another experiment involved keeping flavanols and banana ingredients separate before consumption. Even then, flavanol levels declined, implying PPO’s continued influence even after digestion starts.
It’s important to highlight that bananas remain healthy—they provide potassium, fiber, vitamins, and natural sweetness. They should still be part of a balanced diet.
This research indicates that, if you’re aiming to maximize flavanol intake—especially from berries, cocoa, grapes, or apples—it might be better to skip bananas in your smoothie.
For those wanting to preserve flavanols, using fruits with lower PPO activity, like mango, pineapple, or oranges, is recommended. Yogurt can also be a good addition.
This study underscores a broader concept in nutrition science: the way foods are combined, cooked, or prepared can profoundly influence nutrient absorption, not just the individual foods themselves.
Scientists highlight that understanding these interactions is crucial because many people focus on specific nutrients without considering how foods influence each other inside the body.
The connection to larger nutritional trends is clear—research continues into whether flavanols might support blood vessel health, cholesterol management, blood sugar regulation, and cognitive performance.
Some studies involving cocoa flavanols suggest they could benefit older adults or those with suboptimal diets, though findings are still mixed.
The researchers caution that their study was relatively small, involving only eight healthy men in one part and eleven participants in another. Larger, more diverse studies are needed to confirm these effects.
Nutrition experts advise not to overreact—bananas are still nutritious and beneficial overall. The key takeaway is that food combinations matter in maximizing health benefits.
For smoothie fans, the message is straightforward: if you want creaminess, sweetness, and potassium, bananas are excellent. But if increasing flavanol intake from berries or cocoa is your goal, consider leaving bananas out and pairing those with lower-PPO fruits.
For more insights, explore studies on why vitamin K is vital for seniors or how certain snacks might impact your heart rhythm. Additionally, recent research looks into vitamins that may help prevent type 2 diabetes and chemicals in foods that could affect blood pressure.
This study was published in Food & Function.
Source: University of California, Davis.