Smoothies are a popular and convenient way to incorporate essential fruits and vegetables into your diet. However, recent research conducted at the University of California, Davis, has revealed that the choice of ingredients in your smoothie can impact the nutritional benefits you receive.
The study, recently published in the Royal Society of Chemistry’s journal Food and Function, utilized smoothies to investigate how varying levels of polyphenol oxidase, an enzyme found in many fruits and vegetables, can affect the absorption of flavanols by the body. Flavanols are bioactive compounds known for their heart and cognitive health benefits, naturally present in ingredients like apples, pears, blueberries, blackberries, grapes, and cocoa—common elements in smoothies.
Researchers found that the enzyme polyphenol oxidase (PPO), present in certain fruits such as bananas, can hinder the absorption of heart-healthy flavanols. This is particularly noticeable when these fruits are combined with flavanol-rich ingredients like berries. The study suggests that selecting ingredients with lower PPO activity, such as pineapple or oranges, when creating smoothies could enhance flavanol absorption.
Lead author Javier Ottaviani, affiliated with the UC Davis Department of Nutrition and Mars, Inc., noted the practical implications of the research, aiming to understand how everyday foods like banana-based smoothies affect the availability of flavanols for absorption.
Typically, when fruits like apples or bananas are sliced or exposed to air, their surfaces quickly turn brown due to the action of polyphenol oxidase (PPO). The researchers investigated whether freshly prepared smoothies containing different PPO-containing fruits would influence the body’s access to flavanols.
The study included participants who consumed smoothies made from bananas (high PPO activity) and mixed berries (low PPO activity). Blood and urine samples were analyzed to gauge flavanol levels after consuming the smoothies and a flavanol capsule as a control. Astonishingly, those who consumed the banana smoothie exhibited an 84% reduction in flavanol levels compared to the control group.
The results underscore how food preparation and combinations significantly impact the absorption of dietary compounds. Ottaviani advised those seeking to achieve recommended daily flavanol intake (400 to 600 milligrams) to craft smoothies by pairing flavanol-rich fruits like berries with ingredients boasting low PPO activity, such as pineapple, oranges, mango, or yogurt.
While Ottaviani acknowledged bananas’ nutritional value, he recommended avoiding combinations of high PPO activity fruits like bananas with flavanol-rich counterparts like berries, grapes, and cocoa. The study’s findings raise questions about the preparation of other foods and their effects on flavanols, suggesting the need for further research into this area.
This study highlights the intricate relationship between ingredient choices, preparation methods, and nutritional outcomes, encouraging individuals to optimize their smoothies for maximum health benefits.
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