Impact of polyphenol oxidase on the bioavailability of flavan-3-ols in fruit smoothies: a controlled, single blinded, cross-over study.
Level 2 - randomized trial
Controlled, single-blinded crossover trial in humans
PubMed 37615673 · doi:10.1039/d3fo01599h
What was done
A controlled, single-blind, crossover trial was conducted in healthy men (n = 8) who consumed flavan-3-ols across three conditions: a banana-based smoothie (high polyphenol oxidase [PPO] activity), a mixed berry smoothie (low PPO activity), and a flavan-3-ol capsule (control). A subsequent study (n = 11) tested co-ingestion of flavan-3-ols with a high-PPO banana drink while preventing mixture prior to ingestion. PPO activity was also quantified in 18 fruits, vegetables, and plant-derived products.
What was found
Peak plasma concentration (Cmax) of flavan-3-ol metabolites after capsule intake was 680 ± 78 nmol L⁻¹, similar to levels detected after the low-PPO berry smoothie. Intake of the high-PPO banana smoothie yielded a Cmax of 96 ± 47 nmol L⁻¹, an 84% reduction compared to capsule intake. In the n = 11 group where contact prior to ingestion was prevented, plasma flavan-3-ol levels remained reduced.
Why it matters
Co-ingesting flavan-3-ol sources with high-PPO ingredients like bananas markedly impairs bioactive absorption, suggesting food combination choices directly alter the nutritional value of blended smoothies.
Limits
The study had very small sample sizes (n = 8 and n = 11) and was conducted exclusively in healthy men. Only acute postprandial plasma concentrations were measured rather than long-term clinical health outcomes.