Are Bananas Quietly Stealing Your Smoothie’s Superpowers?

"I love bananas. But these days, I’m a lot more cautious about adding them to my smoothies or mixing them with other fruits." -Alida, our Founder

Bananas are a beloved, convenient, and nutrient‑dense food. And we totally get that they make smoothies better in both flavor and texture.

But...if you’re using smoothies as a daily boost for heart, brain, or metabolic health, you MAY want to think twice about adding bananas.

Today, we're going to show you why combining the right ingredients can seriously change the benefits you get from every sip. 

Because the research on bananas shows that certain fruits, like bananas, can lower the bioavailability of flavanols. 

Yes, THOSE flavanols.

The very same beneficial compounds most of us are trying to boost by adding cocoa, berries, and grapes to our smoothies!

Now, this doesn’t mean bananas are bad. It just means we need to get smarter about food pairing.

Starting With Flavanols 101

Flavanols are a group of polyphenols found in foods like cocoa, berries, grapes, apples, and tea. Regular intake of these compounds has been linked with:

Better vascular function and blood flow

Support for cognitive performance and healthy brain aging

Modulation of inflammation and oxidative stress

But because many people don’t eat enough whole, flavanol‑rich foods from day to day, smoothies have become a convenient way of “concentrating” these nutrients into something fast and easy.

Whether the smoothie (or its counterpart: the smoothie bowl) is in fact a healthy option for everyone may be up for a bit of debate. Some acai bowls contain upwards of 750 calories - made mostly of carbohydrates and fats and not enough protein - can trigger weight gain in certain individuals. Blood sugar issues are definitely a cause for concern so personalized nutrition recommendations are necessary for optimal health of the individual.

But for today, we're sticking to the issue at hand: how certain compounds in the bananas (and other fruits and veggies) can block the absorption of flavanols...thereby decreasing the anti-inflammatory, heart health boosting, and anti-oxidant properties that make these foods 'healing.'

Meet Polyphenol Oxidase (PPO): The Browning Enzyme

You cut apple or banana and see it turn brown. It's not just the air. This is a reaction between Polyphenol Oxidase, an enzyme naturally present in many fruits and vegetables that reacts with polyphenols, and oxygen. 

It’s part of the plant’s defense system, and it changes the chemical structure of certain polyphenols, including flavanols.

Unfortunately, PPO is highly active in bananas! Now you know why your bananas always turn brown before you get a chance to eat them...

"I'll just make banana bread with these..."

But will you though?

PPO stays active throughout the blending process and the early stages of digestion, PPO can convert flavanols into far less bioavailable (usable/absorbable) forms in humans.

Meaning, those beneficial flavanols are no longer useful.

Enzymes are only deactivated with heat, so when you add a raw, high‑PPO fruit to a smoothie that also contains flavanol‑rich foods, you may be sabotaging the very compounds you’re trying to absorb.

The Science: Banana vs. Berry Smoothies

Yes, we brought receipts.

A controlled human crossover at UC Davis decided to ask:

Does adding a high‑PPO fruit to a flavanol‑rich smoothie change how much your body absorbs?

Participants consumed three different treatments on separate occasions:

1. A flavanol capsule (control).

2. A flavanol‑containing banana smoothie (high PPO).

3. A flavanol‑containing mixed‑berry smoothie (low PPO).

Blood and urine samples were collected after each drink to measure flavanol levels. The results were remarkable:

-The banana‑based smoothie led to about 84% lower flavanol levels in the body compared with the control.

-The low‑PPO mixed‑berry smoothie did not show the same dramatic reduction.

-Even when flavanols and bananas were consumed together but not blended, flavanol levels were still significantly reduced, suggesting PPO activity continues after ingestion, likely in the stomach.

Researchers concluded that co‑ingesting high‑PPO foods can substantially reduce the bioavailability of flavanols and likely other polyphenolic bioactives.

High‑PPO vs. Low‑PPO Foods: Yes, The Right Pairing Matters

The study and follow‑up analyses measured PPO activity in a range of fruits and plant foods and found big differences. While specific PPO rankings vary, the practical takeaway is:

Avoid using high‑PPO foods with flavanol-rich ingredients like: bananas, apples, pears, peaches, strawberries, some leafy greens like beet greens, and avocado.

Flavanol-rich foods pair better with lower‑PPO foods like: pineapple, oranges and citrus, mango, yogurt, many greens like kale (especially when lightly cooked), add‑ins like spirulina or some protein powders.

Again, none of this makes bananas or even apples “bad.” It simply means that if your goal is to maximize flavanols from cocoa, grapes, or even berries, tossing in that banana may undercut your efforts.

Rethinking Your Smoothie Strategy

Instead of throwing it all in the blender, think intentionally. Ask yourself, "What’s the purpose of this smoothie?"

If the goal is flavanol therapy (heart/brain/antioxidant support):

Focus on flavanol‑rich ingredients: cocoa, dark chocolate powder, berries, grapes (or 100% grape juice), maybe tea as a base.

Pair them with low‑PPO ingredients:

Liquids: water, coconut water, raw milk, unsweetened almond milk (check labels), yogurt or kefir if tolerated.

Fruit: pineapple, oranges, mango in moderate amounts.

Extras: kale (pre-steamed with an acid like lemon juice and cooled), spirulina, chia or flax seeds, a clean protein powder.

If you love bananas, and want to use them for a fiber boost or post-workout smoothie, avoid adding in cocoa or berries. That way, you’re not wasting your premium ingredients by pairing them in ways that block their absorption.

It's important to note that food is more than a list of 'healthy' ingredients; it’s an intricate network of reactions.

Pair your foods properly and you'll maximize the healing benefits of whatever you take in.

PS...A Little Fun Fact About Bananas and Bees

It's a little lesson Alida learned from a bee keeper.

If you're afraid of bees, you may want to avoid bananas. There's a chemical compound in bananas that resembles the 'alarm' pheromone

When bees smell this, it may cause them to act defensive around you. 

While this is more of a fascination than a major health concern, it is a good reminder that chemistry connects everything, from your smoothie to the hive.

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