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New Research Reveals Bananas Might Diminish Nutritional Benefits of Smoothies
Adding a banana to your smoothie may seem like a healthy choice. However, recent research suggests this popular combination could undermine the beneficial properties of other fruits, particularly berries.
Scientists from the University of California, Davis, have discovered that incorporating a banana into your smoothie can drastically reduce the absorption of essential compounds found in berries, specifically heart- and brain-boosting flavanols, by up to 84%.
The findings, published in the journal Food & Function this month, highlight the role of an enzyme known as polyphenol oxidase (PPO) present in bananas. This enzyme negatively affects the absorption of flavanols, which are crucial for improving cardiovascular and cognitive function.
The Role of Polyphenol Oxidase
Lead researcher Javier Ottaviani, an adjunct professor at UC Davis, explained the research goals, stating, “We aimed to understand how a common food preparation, like a banana-based smoothie, could impact the availability of flavanols post-consumption.”
During a clinical trial, volunteers consumed two types of smoothies—one with banana and the other made with mixed berries, which contain low levels of PPO. Blood and urine tests revealed a marked decrease in flavanol absorption from the banana smoothie, compared to the berry-only version and a flavanol capsule.
Surprising Results on Nutritional Absorption
Ottaviani expressed surprise at the significant effect of adding a single banana to the smoothie, stating, “We were taken aback by the rapid and substantial reduction in flavanol content caused by just one banana.” He also noted that even consuming bananas separately from flavanol-rich foods could still hinder flavanol levels in the body due to PPO’s impact on nutrient absorption.
He advised against combining flavanol-rich foods with those high in PPO, like bananas, avocados, and beet greens. This is critical to maintain the effectiveness of flavanols in the body.
Understanding Flavanol Degradation
Upon blending, PPO reacts with oxygen and initiates the breakdown of flavanols, similar to the browning of fruit after it is cut. This degradation can proceed during digestion, resulting in fewer nutrients available for the body. To maintain optimal flavanol consumption, it is necessary to be mindful of ingredient combinations in smoothies.
Nutrition Guidelines for Optimal Health
The Academy of Nutrition and Dietetics recommends a daily intake of 400 to 600 milligrams of flavanols. To achieve this, Ottaviani suggests pairing flavanol-rich fruits like berries with low-PPO ingredients such as pineapples, oranges, mangoes, or yogurt.
“Bananas are an excellent fruit and offer many health benefits, yet they may not be the best choice if preserving flavanol content in smoothies is the goal,” Ottaviani remarked.
Recommendations from Health Experts
Dr. Parth Bhavsar, a board-certified family medicine physician based in Georgia, emphasized the importance of variety in dietary choices. He suggested, “Moderation and rotation are key. If you enjoy bananas in smoothies, feel free to incorporate them. However, alternating between berry and banana smoothies can be beneficial.”
Bhavsar also pointed out that other common food pairings may impede nutrient absorption. For instance, the tannins in tea can hinder iron absorption, whereas calcium may compete with iron for intake. Raw cruciferous vegetables can affect iodine absorption, and high fiber consumption might limit mineral uptake.
“Although the effects might be minimal in individual cases, they can accumulate over time, leading to significant nutrient deficiencies,” he warned.
Future Implications for Nutritional Research
The researchers at UC Davis noted that these findings could inspire further studies exploring how different food preparation methods affect nutrient absorption. Understanding these interactions is vital for optimizing dietary patterns and enhancing health outcomes.
This study was conducted collaboratively with scientists from the University of Reading in England and King Saud University in Saudi Arabia. It received funding from a research grant provided by Mars, Inc., a well-known partner in cocoa flavanol research. Ottaviani also serves as the director of the Mars Edge Core Laboratory.
Understanding how everyday dietary choices impact health can lead to better food preparation practices and more informed nutritional decisions. This research underscores the need for continued exploration into food interactions and nutrient absorption strategies.
