Wassup you beautiful little chismosas!
If there’s one thing I love, it’s gossip and rumors and talking shit. If there’s one thing I hate, it’s when those rumors contain inaccurate scientific information that misleads the public’s perception of science and health. That’s just a me thing. Really grinds my fuckin gears.
So I’m taking shit into my own hands and starting a new column here on The Uptake called Rumor Has It!
In this column, I’ll be debunking or confirming viral internet rumors, old wives’ tales, or common misconceptions/factoids that have to do with science, while giving a deep dive into the actual science at the root of it.
Now y’all get Mythbusters, but for science. I can’t wait. Your time of having to live under the oppressive weight of falsehood is over now. I’m here, babe. Rejoice.
The best part: similar to Ask A Science Journalist, if you’re a paid subscriber, you’ll be able to submit a viral rumor, old wives’ tale, or factoid that you want me to research and confirm or debunk!
Become a paid subscriber if you got shit that’s been grinding your gears!
For our inaugural Rumor Has It, I’ll be diving into a viral rumor that your daily smoothie may be being corrupted by a household smoothie staple. Let’s blend this shit up and get to the truth!
Do Bananas Actually Make Your Smoothies LESS Healthy?
As you might have seen on TikTok, there’s been talk online about how, if you add a banana to your berry smoothie, the banana actually cancels out all the health benefits of the berries.
In the TikTok, homeboy says that: “there’s an enzyme in the banana that breaks down all the nutritional value of the berries.” But is that true…………
The short answer is: kinda! There is a real scientific basis to this! But this TikTok and the internet have blown it a bit out of proportion.
Bananas won’t destroy all the nutritional value of your berries. Things like fiber, vitamin C, and potassium are completely unaffected. However, bananas drastically reduce your body’s ability to absorb a specific type of healthy antioxidant found in berries called flavanols, which are great for your heart and brain.
Here’s the breakdown of the science behind what is happening in your blender when bananas and berries start fucking (that’s what they’re doing in there).
The Culprit: Polyphenol Oxidase
The enzyme responsible for this mass murder of antioxidants is called polyphenol oxidase (PPO).
In nature, PPO is a plant’s defense mechanism that’s actually meant to cause the mass murder of insects trying to eat the plant.
Under normal conditions, PPO is safely sequestered inside plant cells’ chloroplasts. When an insect chews on a leaf or a pathogen invades tissue, the cells rupture, and the PPOs leak out and mix with oxygen and chemicals called phenols, causing a rapid chemical reaction. What’s left after this is a lot of super-reactive chemicals called o-quinones.
These quinones are toxic and mess up the dietary proteins inside an insect’s gut, making the plant tissue super hard to digest, making it harder for the insect to grow.
Insects quickly learn to avoid plants that make them sick or fail to provide energy. When they try to digest the plant, it causes severe nutritional stress. This leads to post-ingestive aversion (fancy way of saying “this fucked me up, I’m gonna stop eating it), so the insects then stop feeding entirely or move away to find a different, non-defended plant species
Fun fact: PPO is also the exact same enzyme that causes a banana, apple, or avocado to turn brown after you slice it open and expose it to air!
The Study & Why PPO Sabotages Berries
Similar to what happens when an insect's jaws get a hold of plant tissue, when you drop a banana into a blender, the spinning blades crush its cells, releasing massive amounts of PPO.
If there are berries in that same blender, the PPO instantly goes to work, oxidizing and breaking down the berry flavanols.
In the study we talked about up top, researchers at UC Davis compared how well people absorbed flavanols from different smoothies:
The Berry Smoothie: One group of participants drank a mixed berry smoothie.
The Banana-Berry Smoothie: Participants drank a mixed berry smoothie with a banana added.
The Result: Those who drank the banana-berry smoothie had 84% lower levels of flavanols in their blood and urine compared to the banana-free group.
Surprisingly, the study also found that even if you don’t blend them together and instead eat a banana and berries at the same time, flavanol absorption still drops by about 37% because the PPO enzyme keeps working for a bit inside your stomach.
But how exactly does PPO break down flavonols?
The main thing to understand is that antioxidants like flavanols are only healthy because of their specific chemical shape.
On a molecular level, they are covered in little extensions called hydroxyl groups. Think of these groups like a specialized set of hands holding onto extra electrons.
In our bodies, they protect against something called free radicals, which are highly unstable atoms or molecules with at least one unpaired electron that are dying to find stability by stealing an electron to complete themselves.
When a dangerous free radical shows up in your body to cause cellular damage, the flavanol uses these chemical hands to toss over an electron, neutralizing the threat. That is how an antioxidant does its job.
But when you toss a banana into a blender, PPO comes in and fucks up the vibe.
Once those spinning blades crush up the banana’s cells and release that PPO, a whole process kicks off.
Phase 1: Electron Robbery
PPO is a copper-based enzyme, meaning it acts like a powerful chemical magnet.
The second it bumps into a berry flavanol, the flavanol slips into the enzyme like a key into a lock.
Using the extra oxygen from the flavonol as fuel, the PPO enzyme violently plucks the electrons and hydrogen atoms right out of the flavanol’s hands.
Phase 2: Chaotic Cascade
Once a flavonol gets robbed of its electrons, it’s no longer a stable antioxidant. They mutate into those highly reactive, chemically desperate molecules called quinones.
These molecules simply cannot handle being unstable. They panic and immediately start clawing at everything around them to regain balance.
They attack healthy flavanols, proteins, and amino acids in the smoothie, gluing them all together in a frantic chain reaction.
The Result: Giant Molecular Junk
By the time this chain reaction stops, your tiny, easily absorbable berry antioxidants have been forced to link arms and form giant, tangled molecular clumps.
In fact, they have chemically transformed into melanin, the exact same dark pigment that turns an apple brown on your counter and gives human skin its color!
Your gut is perfectly designed to absorb small, nimble, individual flavanol molecules. It has absolutely no idea what to do with a giant, complex melanin clump.
Because the original shape is ruined, your digestive tract can’t absorb it, and the entire clump passes straight through your system without giving you a single ounce of that antioxidant boost.
But just because it’s not nutrient-efficient to add bananas to your berry smoothie specifically, doesn’t mean that there’s no benefit to eating bananas or even adding bananas to your smoothie in general.
Health Benefits of Bananas
Even if they throw a wrench into your berry antioxidants, bananas are still an absolute nutritional powerhouse.
Because they’re packed with specific types of fibers, essential minerals, and easily digestible carbohydrates, they offer major head-to-toe health benefits.
1. Cardiovascular & Blood Pressure Support
Bananas are famous for potassium. A medium fruit delivers about 450 mg, meeting roughly 10% of your daily requirement. Potassium acts as a natural vasodilator, relaxing blood vessel walls and helping the kidneys flush out excess sodium.
A diet rich in potassium directly lowers blood pressure and reduces stroke risk.
2. A Smart Fuel Source for Workouts
There is a reason marathon runners keep bananas at the finish line. They give us a unique dual-energy source:
Quick Energy: Easily digestible simple sugars (fructose and glucose) give an immediate glycogen boost to muscles.
Sustained Energy: Complex carbohydrates provide a slower, steadier release of energy.
Electrolytes: The combination of potassium and magnesium helps maintain proper electrolyte balance.
3. Gut Health & Targeted Digestion
Bananas are also great for your gut, but the way they help actually changes depending on how ripe they are:
Slightly Green/Underripe: These are packed with resistant starch, a powerful prebiotic. It resists digestion in the small intestine and travels straight to the large intestine, where it feeds your beneficial gut bacteria, fermenting into short-chain fatty acids like butyrate that protect your colon lining.
Fully Ripe: As the fruit ripens, that starch turns into simple sugars, and it becomes rich in soluble fiber (pectin). This forms a gel-like substance in your digestive tract, helping soothe the stomach, solidify loose stools, and keep bowel movements regular.
4. Mood & Sleep Support
Bananas contain a helpful combination of Vitamin B6 and tryptophan (an essential amino acid).
Your brain requires Vitamin B6 to convert tryptophan into serotonin, the neurotransmitter responsible for stabilizing mood, reducing anxiety, and promoting feelings of well-being. That same pathway helps produce melatonin, the hormone that regulates your sleep cycle.
A single medium banana provides roughly 25% of your recommended daily intake of Vitamin B6, making it one of the richest plant-based sources of this vital metabolic enzyme companion.
Once you peel it back, yes, bananas do reduce the amount of antioxidants you get if you add them to your berry smoothie, but that doesn’t mean they’re not nutritious on their own.
If you want to maximize banana and berry benefits, just have them on different days, bruv.
Other Nutritional Nullifications
One of the most surprising parts of this internet rumor that helped it gain popularity is the revelation that two foods can chemically cancel each other out.
It sounds obvious when you think about it, but it’s not something we think about.
It also begs the question: if it can happen with something as common as bananas and berries, surely there are other food & beverages combinations that nutritionally nullify each other?
Well, you’d be right, and I’m here to clue you in on ‘em.
Alcohol + B Vitamins (Ethanol vs. Thiamine & Folate)
While it’s not what you’d think of as a nutritional food pairing, enjoying a glass of wine alongside a nutrient-dense meal significantly impairs how your body handles essential B vitamins.
Ethanol (alcohol) technically acts as a systemic toxin that disrupts Thiamine (Vitamin B1) and Folate (Vitamin B9) at the cellular level at every stage of processing. It actively inhibits the specific transporter proteins in your intestinal wall that are responsible for pulling these vitamins into your bloodstream. Alcohol also causes the kidneys to excrete whatever B vitamins you do manage to absorb at a much faster rate.
This means that chronic or even moderate alcohol consumption alongside meals can severely deplete B-vitamin status, which is why long-term heavy drinkers are highly susceptible to neurological issues stemming from severe thiamine deficiency.
To fix this, enjoy your alcoholic drinks well after your meal has had time to digest, rather than washing your food down with them.
Whole Grains + Zinc/Magnesium Foods (Phytic Acid vs. Minerals)
Pairing high-zinc foods (like shellfish or pumpkin seeds) or high-magnesium foods with unsoaked, unfermented whole grains can lock up those vital minerals.
Whole grains, seeds, and legumes contain an organic compound called phytic acid (phytates). Phytates serve as the plant’s storage form of phosphorus, but in the human digestive tract, they function as an intense anti-nutrient. They bind tightly to minerals like zinc, magnesium, and iron, creating insoluble salts that pass completely unabsorbed through your intestines.
Diets heavily reliant on unrefined grains without proper preparation can lead to mineral deficiencies over time, as the phytates continuously lock down the minerals present in the rest of the meal.
To fix this, we’ve developed traditional food preparation techniques such as soaking, sprouting, and sourdough fermentation that activate an enzyme called phytase, which naturally breaks down phytic acid and releases bound minerals.
Raw Cruciferous Vegetables + Iodine Foods (Goitrogens vs. Thyroid Hormone Production)
If you frequently mix raw kale, broccoli, or cabbage into a salad that contains iodine-rich foods (like seaweed, dairy, or seafood), well, oopsie, turns out you can accidentally suppress your thyroid function.
Raw cruciferous vegetables (a family of nutrient-rich plants) are packed with glucosinolates. When these raw veggies are chewed or blended, they break down into compounds called goitrogens (specifically thiocyanates). Thiocyanates look chemically very similar to iodine, and they actively compete with iodine for entry into the thyroid gland, effectively blocking the thyroid from absorbing the iodine it desperately needs to manufacture T3 and T4 metabolic hormones.
Over time, a massive intake of raw goitrogens paired with iodine intake can contribute to an enlarged thyroid (goiter) or sluggish metabolism.
Lightly cooking, steaming, or blanching these vegetables completely deactivates the enzyme responsible for creating goitrogens, allowing you to get all the fiber and vitamins without the thyroid blockade.
High-Dose Zinc + Copper (Mineral Transport Competition)
While not a food pairing, this supplement combo is a classic bottleneck issue that frequently catches people off guard when they take over-the-counter supplements for immune support.
Zinc causes the production of metallothionein, a protein that sequesters copper and traps it inside intestinal cells to block its absorption. Zinc has a much higher binding affinity for this protein than copper does. When you flood your digestive system with high amounts of zinc, it stimulates the production of metallothionein, which then binds up all available copper, trapping it inside the intestinal cells until they are naturally sloughed off and excreted.
Taking high-dose zinc supplements (often found in cold remedies) for more than a few weeks without balancing it with copper can induce a profound, dangerous copper deficiency, leading to anemia and neurological issues.
To avoid this, keep supplemental zinc doses moderate or look for formulations that explicitly include a balanced ratio of zinc to copper.
I hope you enjoyed the first hit of this new vertical on The Uptake! I’m so excited to now be your official scientific Mythbuster.
If you want to use me to debunk or confirm scientific rumors or old wives’ tales you’ve come across, become a paid subscriber, and you can submit a topic!
Otherwise, you can support the work I do hear by sharing with your friends and fam. Don’t be greedy, you little miser. I know you want to keep me all to yourself, but sharing is caring. Go spread the love.