A small UC Davis–affiliated trial reports that a banana-based smoothie markedly lowered the body’s uptake of flavan-3-ols—about 84% less at peak plasma levels than after a control capsule—an effect the researchers link to the fruit’s polyphenol oxidase enzyme.
Researchers from the University of California, Davis, and collaborators report that the type of fruit blended into a smoothie can significantly influence how many flavan-3-ols the body absorbs. The work, published in the Royal Society of Chemistry journal Food & Function, examined the role of polyphenol oxidase (PPO)—the browning enzyme abundant in bananas—in altering flavanol bioavailability. (pubs.rsc.org)
In a controlled, single‑blinded, cross‑over study in eight healthy men, participants consumed three interventions on separate occasions: a banana‑based smoothie (high PPO), a mixed‑berry smoothie (low PPO), and a flavanol capsule (control). Peak plasma flavanol metabolite levels after the banana smoothie were 96 ± 47 nmol/L—84% lower than after the capsule—whereas levels after the mixed‑berry smoothie were similar to the capsule condition. Urine and blood were collected to assess bioavailability. (pubs.rsc.org)
A follow‑up experiment (n=11) suggested the reduction persists even when flavanols and a high‑PPO banana drink are ingested together without pre‑mixing, pointing to a mechanism consistent with post‑ingestion PPO activity in the stomach. The authors emphasize that more research is needed to clarify mechanisms and generalizability. (pubs.rsc.org)
“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,” said lead author Javier I. Ottaviani, of Mars Inc. and UC Davis. He added that the team was “surprised” by how much a single banana decreased flavanol levels, underscoring how food combinations can influence nutrient absorption. (sciencedaily.com)
Contextual guidance: In 2022, an expert guideline developed using the Academy of Nutrition and Dietetics process and published in Advances in Nutrition advised consuming 400–600 mg/day of flavan‑3‑ols from foods to support cardiometabolic health. For people aiming to maximize dietary flavanols, Ottaviani and colleagues suggest pairing flavanol‑rich fruits (e.g., berries) with low‑PPO ingredients such as pineapple, oranges, mango, or yogurt, and avoiding high‑PPO pairings when optimizing for flavanols. According to UC Davis, other high‑PPO items include beet greens. Bananas remain nutritious; the advice pertains to maximizing flavanol intake rather than general diet quality. (nutrition.org)
Authorship and funding: The Food & Function paper lists co‑authors Jodi L. Ensunsa, Reedmond Y. Fong, Jennifer Kimball, Valentina Medici, Gunter G. C. Kuhnle, Alan Crozier, Hagen Schroeter, and Catherine Kwik‑Uribe, with affiliations spanning UC Davis, Mars Inc., the University of Reading, and King Saud University. UC Davis notes the study was funded by a research grant from Mars, Inc. (pubs.rsc.org)
Limitations: The primary crossover study enrolled eight healthy male participants, which may limit broader applicability. The authors call for further work, including on other preparation methods such as tea brewing, a major dietary source of flavanols. (pubs.rsc.org)