Smoothies have long been hailed as a quick and tasty way to boost our daily fruit intake. However, recent findings from the University of California, Davis, suggest that not all smoothie ingredients are created equal. This groundbreaking research sheds light on why bananas might not be the ideal addition to your blended concoctions, particularly when combined with certain other fruits.
The surprising impact of polyphenol oxidase on smoothie nutrition
At the heart of this discovery lies an enzyme called polyphenol oxidase (PPO). This naturally occurring compound is responsible for the browning we observe when certain fruits, like apples or bananas, are cut or bruised. While this process might seem harmless, researchers have uncovered its potential to significantly reduce the absorption of beneficial compounds in our bodies.
The study, published in the Royal Society of Chemistry’s journal Food and Function, focused on how PPO affects the bioavailability of flavanols in smoothies. Flavanols are a group of bioactive compounds known for their positive effects on heart and cognitive health. They’re commonly found in popular smoothie ingredients such as :
- Apples
- Pears
- Blueberries
- Blackberries
- Grapes
- Cocoa
Lead author Javier Ottaviani, director of the Core Laboratory of Mars Edge and 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.”
Bananas vs. berries : The flavanol absorption showdown
To investigate the effects of PPO on flavanol absorption, researchers conducted a controlled experiment. Participants consumed three different preparations :
- A smoothie made with banana (high PPO activity)
- A smoothie made with mixed berries (low PPO activity)
- A flavanol capsule (control)
The results were striking. Blood and urine samples revealed that those who drank the banana smoothie had a staggering 84% lower levels of flavanols in their bodies compared to the control group. This significant reduction in flavanol absorption caught the researchers off guard.
Ottaviani expressed his surprise at the findings : “We were really surprised to see how quickly adding a single banana decreased the level of flavanols in the smoothie and the levels of flavanol absorbed in the body. This highlights how food preparation and combinations can affect the absorption of dietary compounds in foods.”
Optimizing your smoothie for maximum health benefits
In light of these findings, health-conscious smoothie enthusiasts may want to reconsider their ingredient choices. The Academy of Nutrition and Dietetics recommends consuming 400 to 600 milligrams of flavanols daily for optimal cardiometabolic health. To achieve this goal while enjoying delicious smoothies, consider the following tips :
| High PPO Activity (Avoid) | Low PPO Activity (Recommended) |
|---|---|
| Bananas | Pineapple |
| Beet greens | Oranges |
| Apples | Mango |
| Yogurt |
When preparing smoothies, combine flavanol-rich fruits like berries with ingredients that have low PPO activity. This approach will help maximize the absorption of beneficial compounds. It’s important to note that bananas remain a nutritious fruit and can still be enjoyed in smoothies. However, for those looking to optimize their flavanol intake, it’s best to avoid combining bananas with flavanol-rich ingredients like berries, grapes, and cocoa.
Future implications and ongoing research
This groundbreaking study opens up new avenues for research into food preparation and its effects on nutrient absorption. Ottaviani suggests that similar principles could apply to other popular sources of flavanols, such as tea. Depending on how tea is prepared, the amount of flavanols available for absorption may vary significantly.
“This is certainly an area that deserves more attention in the field of polyphenols and bioactive compounds in general,” Ottaviani remarked. As our understanding of these interactions grows, we may see further refinements in dietary recommendations and food preparation techniques.
The study, funded by a research grant from Mars, Inc., brought together a diverse team of experts. Contributors included researchers from the UC Davis Department of Nutrition, UC Davis Department of Internal Medicine, University of Reading, King Saud University, and Mars, Inc. This collaborative effort underscores the importance of interdisciplinary research in advancing our understanding of nutrition and health.
As we continue to unravel the complexities of food science, it’s clear that seemingly simple choices, like adding a banana to a smoothie, can have profound effects on our nutritional intake. By staying informed and making mindful decisions about our food combinations, we can harness the full potential of nature’s bounty and optimize our health outcomes.
Allan is out in the field, at the heart of the action. Specializing in local reports and in-depth investigations, he has a knack for revealing the stories behind our city’s facades.
