Bananas in Smoothies May Slash Flavanol Benefits by 84%, Study Finds

A new study from UC Davis reveals that adding a banana to a smoothie may cut the body's absorption of flavanols by up to 84%. These compounds, found in foods like berries and dark chocolate, are linked to heart health, better blood pressure, and improved brain function. The findings suggest a simple swap could help maximise the benefits of flavanol-rich drinks.

Flavanols belong to a group of plant compounds called flavonoids, known for their antioxidant and anti-inflammatory effects. They appear in cocoa, tea, apples, grapes, and leafy greens, as well as red wine and citrus fruits. Research increasingly ties long-term flavanol intake to lower risks of cognitive decline and dementia, alongside improvements in vascular health and insulin sensitivity.

The UC Davis study pinpoints bananas as the culprit behind reduced flavanol absorption. The fruit contains polyphenol oxidase, an enzyme that breaks down flavanols during blending. While smoothies often combine multiple fruits for broader nutritional benefits, this reaction can significantly lower the amount of flavanols the body actually uses. For those relying on smoothies as a main source of flavanols, researchers recommend replacing bananas with alternatives. Options like berries, cantaloupe, or mango provide a similar creamy texture without the same enzyme interference. Occasional banana-berry smoothie drinkers, however, need not make changes—only frequent consumers may see a noticeable impact.

The study highlights a straightforward adjustment for smoothie lovers aiming to boost their flavanol intake. By choosing banana-free bases, people can better preserve the heart- and brain-protective properties of their drinks. Meanwhile, the broader benefits of flavanols—from supporting circulation to cognitive health—remain well-documented in everyday foods.