According to the claim “Eating nine bananas in a row can kill you by giving you a lethal overdose of potassium”
Potassium is a good thing. It is also a bad thing. It is an essential element in the human body and a crucial part, along with sodium, of maintaining fluid and electrolyte balance in the body. It is the principal cation inside the body’s cells and helps to maintain their integrity. It is a part of nerve impulses, muscle contraction, and adrenal gland function. Too little potassium, called hypokalemiais a disaster for your body. It can lead to high blood pressure, kidney stones, bone turnover, irregular heartbeat, muscle weakness, glucose intolerance, and ultimately, if the deficiency becomes severe enough, death.
See also Will Too Much Salt Give Me High Blood Pressure?
Potassium is also a toxin. Too much potassium can kill you. In fact, if enough potassium is injected into a vein, it will stop the heart. For this reason, it is part of lethal injections.
Bananas are one fruit with a reputation for having a lot of potassium. In fact, potassium is probably the only nutrient most people can name in regards to bananas. However, if you were to check the recommended levels of potassium from the diet (meaning from food), you would find that there is no upper limit set! An adequate level for an adult is around 4700 mg per day but this is not the upper amount. If too much potassium is so dangerous, shouldn’t there be a daily limit?
Nine Bananas Will Not Give You a Potassium Overdose
Well, it is close to impossible, if not outright impossible, to get potassium toxicity from eating too many high-potassium foods. When you take in more potassium than your body needs, the kidneys will simply excrete more of it. Your body is very good at maintaining its potassium and sodium balance. To disrupt this balance, you need to consume a very high level of potassium-containing salts, supplements, or perhaps certain energy drinks. Otherwise, a person may have too much potassium as a result of certain diseases or medical treatments.
People with kidney disease (especially if on dialysis) may sometimes need to avoid potassium-rich foods. Certain medications may also interfere with the body’s ability to excrete potassium.
Those with hypertension or complications from diabetes may be prescribed potassium supplements. Overdoing these supplements can be dangerous, as they contain much higher levels than would ever be found in a food.
Normally, however, if potassium is taken into a healthy body via the digestive system it is difficult to reach toxic levels. If the digestive system is bypassed, as in injections mentioned above, potassium becomes extremely dangerous.
So, you can see that eating nine bananas or even a dozen would not result in any sort of potassium toxicity. In fact, eating a lot of any potassium containing food is not likely to be dangerous to an otherwise healthy person. Bananas do not even contain as much potassium as certain other foods. 1
How Many Bananas Would You Have to Eat?
Any sort of estimate as to the number of bananas you would have to eat in a row in order to get an overdose of potassium is, in fact, silly. The reason it is silly is that your body will continually adjust and maintain your potassium level as you eat and you will probably become ill due to simple overeating before you could overcome your kidney’s ability to excrete the excess, even if you could eat fast enough.
Attempts to calculate the number of bananas based on oral intake levels result in numbers such as 487 bananas a day, or half that number if potassium-chloride is considered rather than pure potassium. 2
Besides muscle weakness, potassium toxicity would cause vomiting. You would undoubtedly be vomiting due to the sheer amount of banana long before you could poison yourself, if possible at all.