Recent Study Advises Against Incorporating Bananas in Flavanol-Rich Smoothies

A scientific investigation has revealed that the presence of the enzyme polyphenol oxidase (PPO) in specific fruits, such as bananas, can impede the body’s ability to absorb beneficial flavanols. Particularly when paired with flavanol-abundant foods like berries, this can occur. The research advocates for the selection of fruits with minimal PPO activity, like pineapples or oranges, to enhance flavanol uptake when crafting smoothies.

Recent findings aim to optimize the nutritional gains from fruit-based smoothies.

Smoothies serve as a convenient and palatable way to include crucial fruits and vegetables in one’s daily nutrition. However, is a combination of bananas and blueberries the most advantageous choice? A new study conducted by the University of California, Davis proposes that the type of ingredients used in smoothies can significantly impact the nutritional benefits your body derives.

The research, recently published in Food and Function, a journal by the Royal Society of Chemistry, employed smoothies to examine how varying concentrations of polyphenol oxidase affect the bioavailability of flavanols in the food consumed. Flavanols are bioactive compounds beneficial for heart and cognitive health and are commonly present in foods like apples, pears, blueberries, blackberries, grapes, and cocoa — often used in smoothie recipes.

Javier Ottaviani, the lead author of the study and director of the Core Laboratory of Mars Edge, along with being an adjunct researcher with the UC Davis Department of Nutrition, stated, “The objective was to comprehend, at a pragmatic level, how ordinary foods and their preparation methods, like those involved in making a banana-based smoothie, could impact the body’s absorption of flavanols.”

When fruits like apples or bananas are sliced or peeled, they tend to brown quickly. This phenomenon occurs due to the natural presence of polyphenol oxidase. The researchers aimed to determine whether freshly prepared smoothies made with fruits that have varying levels of PPO activity affect the flavanols that become bioavailable.

Comparing Bananas and Berries

The research team had participants consume smoothies made either with bananas, which have a high natural PPO activity, or with mixed berries that have a low natural PPO activity. Participants were also given a flavanol capsule as a control group. Blood and urine samples revealed that the flavanol levels in those who consumed the banana smoothie were 84% lower compared to the control.

Ottaviani noted, “We were intrigued to find how swiftly a single banana reduced not only the flavanol levels in the smoothie but also the bioavailability of flavanols in the body. This underscores how food preparation and combinations can influence the absorption of dietary nutrients.”

In the previous year, the Academy of Nutrition and Dietetics recommended that people should consume between 400 and 600 milligrams of flavanols daily for cardiometabolic well-being. According to Ottaviani, those targeting such flavanol intake should consider creating smoothies by combining flavanol-rich fruits like berries with ingredients that also exhibit low PPO activity, such as pineapples, oranges, mangoes, or yogurt.

While bananas continue to be a nutritious fruit, Ottaviani suggests avoiding pairing them with flavanol-rich fruits like berries, grapes, and cocoa in smoothies. The outcomes of this study may pave the way for future inquiries into the preparation methods of other foods and their impact on flavanol absorption. For instance, tea, another major dietary source of flavanols, might offer different levels of bioavailability based on preparation methods.

Ottaviani concluded, “Further exploration is warranted in the area of polyphenols and bioactive compounds.”

Reference: “Impact of polyphenol oxidase on the bioavailability of flavan-3-ols in fruit smoothies: a controlled, single blinded, cross-over study” by Javier I. Ottaviani, Jodi L. Ensunsa, Reedmond Y. Fong, Jennifer Kimball, Valentina Medici, Gunter G. C. Kuhnle, Alan Crozier, Hagen Schroetera and Catherine Kwik-Uribe, 24 August 2023, Food & Function. DOI: 10.1039/D3FO01599H

Contributors to the study include Jodi Ensunsa, Reedmond Fong, Jennifer Kimball, and Alan Crozier, who are affiliated with the UC Davis Department of Nutrition, along with researchers from the UC Davis Department of Internal Medicine, University of Reading, King Saud University, and Mars, Inc.

The study received financial support from a research grant provided by Mars, Inc., which collaborates with research entities to explore the potential health benefits of cocoa flavanols.

Frequently Asked Questions (FAQs) about Flavanol Absorption in Smoothies

More about Flavanol Absorption in Smoothies

• UC Davis Department of Nutrition
• Food & Function Journal
• Academy of Nutrition and Dietetics Flavanol Recommendations
• Mars, Inc. Research Initiatives
• Polyphenol Oxidase in Fruits
• Royal Society of Chemistry
• University of Reading Research
• King Saud University Research