If you’re eating a banana while reading this, congratulations! You’re doing your heart a favour. On this National Banana Day 2025, celebrated every third Wednesday of April, there’s a new reason to peel and smile.
A study from the University of Waterloo suggests that bananas (and other potassium-rich foods) may be more effective at reducing high blood pressure than the long-standing advice to simply cut back on salt. At a time when over 30% of adults worldwide suffer from hypertension, this yellow fruit might just be the affordable, accessible, and surprisingly powerful solution we've overlooked for too long.
Potassium vs. Sodium, Not Just Sodium Alone
Traditionally, managing high blood pressure has focused on reducing sodium intake... and for good reason. Excess salt increases fluid retention, raising blood volume and straining the arteries. But this new study asks, what if it’s not just about salt, but also about potassium?
According to Professor Anita Layton, Canada 150 Research Chair in Mathematical Biology and Medicine and a professor at the University of Waterloo, “Usually, when we have high blood pressure, we are advised to eat less salt. Our research suggests that adding more potassium-rich foods to your diet, such as bananas or broccoli, might have a greater positive impact on your blood pressure than just cutting sodium.”
This means the real key could be your potassium-to-sodium ratio: how much potassium you're getting relative to salt.
How It Works
Potassium and sodium are both electrolytes: minerals that help regulate fluid balance, nerve signals, and muscle contractions. But they do more than just support workouts and hydration. Together, they play a tug-of-war in controlling blood pressure.
Too much sodium causes your body to hold onto water, increasing blood pressure. Potassium, however, helps your body excrete sodium through urine and relaxes blood vessel walls, resulting in lower pressure and better circulation. Lead author Melissa Stadt, a PhD candidate in Waterloo's Department of Applied Mathematics, points out that our ancestors likely consumed diets high in potassium and low in sodium, thanks to a fruit-and-vegetable-heavy lifestyle.
“Today, western diets tend to be much higher in sodium and lower in potassium. That may explain why high blood pressure is found mainly in industrialized societies, not in isolated societies,” she says.
Using a mathematical model that simulates how potassium and sodium interact in the body, the Waterloo research team showed how boosting potassium intake (particularly in relation to sodium) can significantly lower blood pressure. They also found notable sex-based differences: while men are more prone to developing hypertension, they also respond more effectively to increased potassium intake than premenopausal women.
This study is particularly exciting because it uses ethical, fast, and cost-effective modeling tools to explore real-world dietary impacts on health, without the need for large-scale clinical trials.
How Many Bananas Should You Eat?
A medium banana contains about 422 mg of potassium, which is around 9% of the recommended daily intake for an average adult (about 4,700 mg). So while one banana a day is a great start, you’ll want to complement it with other potassium-rich foods like:
- Spinach
- Sweet potatoes
- Avocados
- Beans and lentils
- Yoghurt
- Broccoli
- Oranges
If you're watching sodium, it's not just about skipping the salt shaker. Hidden sodium is everywhere: in packaged snacks, breads, pickles, cheese, and sauces. Balancing it out with potassium-rich food is a smarter, more sustainable approach.
More Reasons to Love Bananas
Beyond their blood-pressure-lowering potential, bananas pack a nutritious punch:
- Natural energy boost: Great source of carbohydrates, especially before a workout.
- Gut-friendly: Bananas contain resistant starch and prebiotics that feed good gut bacteria.
- Mood support: Rich in vitamin B6, bananas help produce serotonin, the "feel good" hormone.
- Heart health: Aside from potassium, bananas are low in cholesterol and fat—making them heart-friendly.
- Bone strength: Contain small amounts of magnesium and manganese for bone health.
- They're affordable, travel well, and require zero preparation.
While bananas are a powerful ally in your health journey, moderation is still key. People with chronic kidney disease may need to monitor their potassium levels, as their kidneys may not eliminate excess potassium effectively. Always consult a doctor or a registered dietician if you're making significant dietary changes, especially if you have pre-existing conditions.
Reference:
https://journals.physiology.org/doi/full/10.1152/ajprenal.00222.2024
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