How Bananas in Smoothies May Impact Flavanol Absorption: What You Need to Know

Smoothies are a popular way to pack nutrients into your diet, but a recent study from the University of California, Davis, suggests that the combination of ingredients can significantly affect how your body absorbs key compounds. Specifically, the enzyme polyphenol oxidase (PPO) found in bananas may reduce the availability of flavanols—powerful antioxidants linked to heart and brain health—when blended with other ingredients like berries.

The Science Behind the Findings

The study, published in the *Royal Society of Chemistry’s journal Food & Function*, investigated how PPO activity in fruits influences flavanol absorption. Flavanols are bioactive compounds present in foods such as apples, pears, blueberries, blackberries, grapes, and cocoa. These compounds are associated with improved cardiovascular and cognitive health.

Researchers led by Dr. Javier Ottaviani, director of the Core Laboratory of Mars Edge (part of Mars, Inc.) and an adjunct researcher with UC Davis, found that blending bananas—high in PPO—with flavanol-rich ingredients like berries drastically reduced the amount of these compounds available for absorption. In experiments, banana-based smoothies cut flavanol absorption by 84% compared to smoothies made with low-PPO ingredients like mixed berries.

Understanding Polyphenol Oxidase (PPO)

PPO is the enzyme responsible for the browning of fruits like apples and bananas when they are cut or bruised. While this process is well-known, its impact on nutrient absorption during food preparation was less understood. The UC Davis team discovered that PPO activity persists even after blending, potentially affecting the bioavailability of flavanols in the digestive system.

In a controlled trial, participants consumed banana-based smoothies, berry-based smoothies, and a flavanol capsule. Blood and urine analysis revealed that flavanol levels were 84% lower in those who drank the banana smoothie compared to the control group. The berry smoothie, however, produced flavanol levels comparable to the capsule, highlighting the role of PPO in nutrient interaction.

Practical Implications for Smoothie Lovers

While bananas remain a nutritious choice—offering fiber, potassium, and natural sweetness—the study underscores the importance of ingredient pairing when aiming to maximize flavanol intake. For those prioritizing heart-healthy compounds, the researchers recommend combining flavanol-rich fruits like berries with low-PPO ingredients such as pineapple, oranges, mango, or yogurt.

“This highlights how food preparation and combinations can affect the absorption of dietary compounds,” Ottaviani said. “A smoothie is not just a pile of nutrients in a glass—it’s a complex interaction of ingredients.”

What This Means for Your Diet

The study does not discourage banana consumption but emphasizes strategic pairing. For example, bananas can still be enjoyed for their creaminess and potassium content, but they may not be the best choice when the goal is to boost flavanol intake from berries, grapes, or cocoa.

The Academy of Nutrition and Dietetics recommends 400–600 milligrams of flavanols daily for cardiometabolic health. Foods like tea, apples, berries, grapes, and cocoa are primary sources. However, the UC Davis research suggests that preparation methods and ingredient interactions can influence how much of these compounds your body actually absorbs.

Limitations and Next Steps

The study involved a small sample size, with 8 participants in the initial trial and 11 in a follow-up. While the findings are intriguing, further research is needed to confirm these effects across diverse populations. Nutrition experts caution against overreacting to the results, noting that smoothies with bananas can still be part of a balanced diet.

“The best takeaway is simple: ingredient combinations can change what your body gets from food,” said Dr. Ottaviani. “This is an area that deserves more attention in the field of polyphenols and bioactive compounds.”

Key Takeaways

• Bananas contain PPO, an enzyme that may reduce flavanol absorption when blended with certain fruits.
• Flavanols, found in berries, grapes, and cocoa, are linked to heart and brain health.
• To maximize flavanol intake, pair low-PPO ingredients like berries with pineapple, mango, or yogurt.
• Bananas remain nutritious but may not be ideal for smoothies focused on flavanol-rich foods.
• Further research is needed to validate these findings and explore broader implications for dietary practices.

As nutrition science continues to evolve, understanding how food interactions affect nutrient absorption can empower individuals to make informed choices. Whether you’re a smoothie enthusiast or simply looking to enhance your diet, the key is balance and mindful ingredient selection.