Research Reveals Key to Boosting Nutrient Absorption in Smoothies

Smoothies have gained popularity as a convenient and tasty way to incorporate essential fruits and vegetables into one’s diet. However, recent research conducted by the University of California, Davis, highlights that the combination of ingredients in a smoothie can play a significant role in how effectively the body absorbs important nutrients. 

Published in the journal Food and Function, the study delves into the impact of polyphenol oxidase (PPO), an enzyme commonly found in various fruits and vegetables, on the absorption of flavonols by the body. Flavanols are a type of bioactive compound that offers benefits for heart health and cognitive function. These compounds naturally occur in foods like apples, pears, blueberries, blackberries, grapes, and cocoa – ingredients that are frequently used in smoothies. 

Lead author Javier Ottaviani, who is the director of the Core Laboratory of Mars Edge and an adjunct researcher with the UC Davis Department of Nutrition, explained the study’s objective: “We sought to understand, on a very practical level, how a common food and food preparation like a banana-based smoothie could affect the availability of flavanols to be absorbed after intake.” The researchers’ investigation was rooted in the enzymatic process that leads to the browning of fruits upon exposure to air, cutting, or bruising.

This enzymatic process is driven by PPO or polyphenol oxidase. To determine how PPO-containing fruits impact flavanol availability, participants in the study consumed smoothies made from high-PPO activity fruits like bananas and low-PPO activity fruits like mixed berries. A control group took a flavanol capsule. Blood and urine samples were collected and analyzed to assess flavanol levels in the body after ingestion of the smoothies and capsule. 

Surprisingly, the findings revealed that individuals who consumed the banana-based smoothie experienced an 84% reduction in flavanol levels compared to the control group. Ottaviani expressed his surprise at the speed at which the addition of a single banana diminished flavanol levels both in the smoothie and in the body. This discovery underscores the importance of food preparation and ingredient combinations in influencing nutrient absorption. 

To support cardiometabolic health, the Academy of Nutrition and Dietetics recommends a daily intake of 400 to 600 milligrams of flavanols. Ottaviani suggests that those aiming to meet this requirement should consider crafting smoothies that combine flavanol-rich fruits, such as berries, with ingredients low in PPO activity, like pineapple, oranges, mangoes, or yogurt. For those who still desire the inclusion of bananas or other high-PPO activity fruits and vegetables, Ottaviani advises against combining them with flavanol-rich counterparts like berries, grapes, and cocoa. 

While Ottaviani acknowledges that bananas remain a valuable fruit for consumption, he emphasizes that individuals seeking the benefits of flavanols should thoughtfully construct their smoothies to optimize nutrient absorption. This advice aligns with the study’s implications for food preparation practices – an area ripe for exploration. Ottaviani points out that tea, a significant dietary source of flavanols, could also experience varying flavanol availability based on its preparation method. 

The research team anticipates that their findings will motivate further investigations into the preparation of various foods and their effects on nutrient availability. Ottaviani believes that the study has broader implications: “This is certainly an area that deserves more attention in the field of polyphenols and bioactive compounds in general.” Contributors to the research included Jodi Ensunsa, Reedmond Fong, Jennifer Kimball, and Alan Crozier, all affiliated with the UC Davis Department of Nutrition, as well as researchers from the UC Davis Department of Internal Medicine, University of Reading, King Saud University, and Mars, Inc. 

The study conducted at the University of California, Davis, sheds light on the intricate interplay between food ingredients and nutrient absorption. While smoothies offer a convenient and palatable means of meeting dietary requirements, their nutritional efficacy is influenced by ingredient selection and preparation methods. As the field of nutrition continues to evolve, researchers and health-conscious individuals alike are prompted to consider not only the nutrients present in their meals but also the complex interactions that govern their absorption.