How Many Bananas Does It Take to Poison You?

Eating a single banana or even a whole bunch won't poison you, but if you eat too many the excess potassium can harm you. (robin_24)
Eating a single banana or even a whole bunch won’t poison you, but if you eat too many the excess potassium can harm you. (robin_24)

You probably know too much water and too many apple or cherry seeds can kill you, but did you know eating too many bananas may lead to an early demise? It’s not their high radiation signature. It’s because bananas contain potassium. But wait, you may be saying, isn’t potassium good for me? It is, but like everything else, too much potassium is bad for you. Too much potassium can lead to heart damage and cardiac arrest.

I was reminded of that when reading about an attempt to set a new world record for eating bananas. Apparently the world record effort has been scaled back so that it involves more people eating bananas and not people eating as many bananas as possible. The reason for the change was to prevent health problems or death from over-eating bananas.

I couldn’t help but wonder exactly how many bananas you would have to eat in order to ingest a dangerous amount of potassium. I mean… what are we talking about here? Three bananas? Ten? I have a friend who ate 7 bananas as part of some weird man-challenge. He isn’t dead and didn’t go into cardiac arrest, but he assures me that is nearing the upper limit of banana-eating. How many bananas do you think it takes to poison you with potassium?


Meri says:

I, as a banana lover since childhood, often eat as many as I buy, which is usually 5 or more during an evening. And I suppose that I HAVE eaten more, and yet no noticable damage has ever occurred.Judging by the information given at (a site I do trust) an average banana has 13.4% of the recommended daily amount of potassium, so 7-8 bananas, if you don’t eat any other foods that are ich in potassium, seems to be the daily norm potassium-wise. Maybe all is not that dangerous

John says:

Great question!

Here’s what I found on the subject: “The normal level of potassium in the bloodstream is in the range of 3.5-5.0 mM, while levels of 6.3-8.0 mM (severe hyperkalemia) result in cardiac arrhythmias or even death due to cardiac arrest. Potassium is potentially quite toxic, however toxicity or death due to potassium poisoning is usually prevented because of the vomiting reflex. The consumption of food results in mild increases in the concentration of potassium in the bloodstream, but levels of potassium do not become toxic because of the uptake of potassium by various cells of the body, as well as by the action of the kidneys transferring the potassium ions from the blood to the urine. The body’s regulatory mechanisms can easily be overwhelmed, however, when potassium chloride is injected intravenously, as high doses of injected potassium can easily result in death.” (Source:

Knowing that, it seems like one could calculate how many bananas would need to be eaten to get that level of potassium in the blood. I’m assuming this is where calculus (ack!) would come in: Let’s say it takes 100 bananas for easy math. By the time you get to the 50th banana, maybe the potassium from the first five bananas has already finished its “tour” in the bloodstream and you know have to eat five more. You may never catch up!

Tomato Addict says:

It only takes ONE banana!

Bob S says:

Bananas are rich in vaso active amines – particularly when they are green. Is it possible that this is the origin of their reputed toxicity?

Sam says:

Well, I have pseudohypoaldestronism Type 2, and if I have way too many bananas or anything with too much potassium I can get very ill. The end result can easily be a heart attack because my blood pressure could easily get out of control.. I am taking hydrochlorothrozide which, well duh, lowers my blood pressure.

Raj Sharma says:

My blood pressure had started going up-150/110. I started taking 7 bananas and 3 plums everyday. In three weeks my BP came down to 120/80. Of course I did other things like cutting down drastically on salt, saturated fats etc.

Penny says:

I always had a banana for breakfast and I was a heavy smoker and I was in a rush and I found out that way that bananas are not entirely good for your heart because my heart was racing and I just didn’t feel very healthy. I stopped eating bananas after my morning cigarette soon after and felt a lot better. I was just reading bananas are supposed to be good for your if you want to quit smoking but I disagree after that. I don’t smoke anymore and eat a balanced diet so problem solved there.

susan says:

I highly doubt that bananas are toxic. I am even wondering whether you are talking about something different:may be strange species of banana! You never know, but from the snap am seeing, it is the usual banana i have consumed ever since i was weaned. Bananas are ma staple food. We eat bananas from Jan to Dec year after year; but i have never even heard of any single complaint due to bananas. We have different species: food (meals), snacks, juice or local brew, fruit to mention but a few. I have never heard of anyone in ma home area grumbling, and i do not expect to hear that in the near future!

Heather says:

People do not realize that the body needs 4,500 of potassium a day which many of us are lucky if we get 1,000 a day a lack of potassium can cause so many health problems mostly heart and muscle disease. Yogurt has potassium in it, as well as fruits like bananas strawberries, and tuna fish. I would think its impossible to get too much of this. I would look on the back of labels and see how much it has in it. Another important vitamin is magnesium, that too is hard to get enough of in 24 hours.

Rob says:

A person can eat up to 8 bananas a day and be ok as long as you don’t get other potassium foods.

rahul says:

I eat on average 25-30 bananas a day, with about a dozen at a time. I have had no heart problems. There is no such thing as “too many bananas”.

Karlin says:

A average-size banana contains 500 mg of potassium; If we need 5000 mgs per day, then about 10 would be ideal if that is our only potassium source. Bananas are wonderful food, one of few that a person can eat only that and survive.

richard murphy says:

you can live on bananas. the bbc did an experiment, chlesterol dropped 23%, the volunteers were happier, blood pressure dropped massively…

our nearest biological and genetic cousins live on them. my friend ate nothing other than bananas for 5 weeks, i’ve never seen him look so healthy and radiant.

Bandana says:

I can’t find any records of anyone ever being killed by eating a banana except from a heart attack caused by choking on a banana or by slipping on a banana peel. Water can rid you of the excess dietary potassium. If you have diabetes, however, the high level of blood sugar from to many bananas can eventually destroy your capillaries and kill you.

jeremy says:

since i was a child i have loved bananas, though now i cant eat them due to my acid reflux. im not sure exactly why they hurt my esophagus, but every time i eat them, it gets very painful.

before they started bothering me, however, i would eat at least 4 a day, most of the time more. i have eaten 15 in one day (but that was not in one sitting, it was throughout about 10 hours), and i am mostly fine. i think as long as you drink a lot of water you would be ok.

nolan says:

It takes 190g of oral potassium to kill a 165lb person. If each banana contains approximately 500mg, that means that person would have to eat 95 bananas to cause cardiac arrest.

bob says:

nice math, but it would actually take 380 according to your findings (500mg = 1/2 gram)

Joyce S. says:

Okay, whatever! One banana can NOT give you potassium poisoning!

Bananas in general can’t hurt anyone (unless you’re allergic to them), but too much potassium can. Like Nolan wrote; “It takes 190g of oral potassium to kill a 165lb person. If each banana contains approximately 500mg, that means that person would have to eat 95 bananas to cause cardiac arrest.”

So, eat your bananas, and stop worrying!

Derek says:

My best friend’s ex-girlfriend is a strict vegetarian and used to eat lots of bananas every day, She ended up with Potassium poisoning, so yes it does happen. I imagine she had been eating a lot of them for a long time before it got to that dangerous level. The diagnosis was made by a doctor who recommended she cut down on the bananas and she’s been fine ever since.

Patrick says:

Table 9.2 Safe upper level (or guidance level) and effect of excess for selected metals.
Metal Safe upper level per day/mg (adult) Problem
potassium * (3700) stomach pain, nausea, diarrhoea
sodium * (2300) increased blood pressure (hypertension) increasing risk of heart attack or strokes
calcium * (1500) stomach pain, diarrhoea, kidney stones, milk alkali syndrome
magnesium * (400) diarrhoea
iron * (17) constipation, stomach pain, cirrhosis of liver, impaired heart function and failure
zinc 25 reduces absorption of copper and iron, leading to anaemia and weakening of bones
copper 10 stomach pain, damage to the liver and kidneys.
* Insufficient data to establish a safe upper level – value given is a guidance value for supplemental doses producing no adverse reaction.

(38) Everyday Bikeathon says:

I bike to work 26 miles a day. When I get there a man selling fruit gives up to a dozen small bananas for a dollar.. Sometimes I eat all of them without sharing throughout the day. They are always ripe and sometimes I through away the funky part. Somebody told me that maybe I should not be eating so many bananas but it has been a while and I am still doing great. I notice that Mc Donalds sells two breakfast sandwiches for three dollars and lots of people get into that routine. I think to be fair 12 bananas a day for a dollar is much safer and healthier than 10 breakfast sandwiches a week and not to mention more filling and 10 dollars cheaper. I don’t think I am making any intelligable point here put that what I was thinking. Maybe I should starting eating an orange and 3-4 bananas. I should also avoid donuts and hashbrowns and anything via Mickey D’s.

Katy says:

You’d have to eat quite a few and not urinate. Your kidneys would get rid of the excess nutrient.

Alexandra says:

I have high potassium and when I eat even half of a banana I feel like my heart will pop out my chest at any given moment.

Robin Nixon says:

Actually you can overdose on bananas and give yourself arrhythmias (irregular heart beat), if you are also on a potassium drug for lowering blood pressure. In which case you can go past the maximum dose level quite easily. And if you also use a low salt alternative containing potassium then you are definitely going to feel the effect if you also have too many bananas. Basically, if you are on a potassium drug you should use very little low salt and only 1 banana a day to avoid possible side effects.

erlar says:

The toxicity of bananas might not come from potassium but from oxalic acid;
they contain a lot of it and it may cause lithiase.

julie says:

I’m known for my strange eating habits but I have about 16 apples and about 6 bananas a day. If I didn’t I would have bowel problems and therefore be on medication.

Mike says:

I crunched in the numbers and here’s what I got: for a person weighing 60 kg, you will only need 17-18 bananas to induce a cardiac arrest. The actual number might be higher because the kidneys remove excess potassium from the bloodstream.

Here are some of the data and assumptions I worked with:

-each banana contains 450mg of potassium
-the normal blood concentration of potassium is 3.5-5.0mM
-the concentration of potassium needed to induce a cardiac arrest is 6.3-8.0mM
-a human body is 60% water (w/w)
-To keep my calculations simple, I didn’t consider the natural capability of the kidneys to remove excess electrolytes.
-I didn’t involve other xenophobic proteins in the body that might fight against potassium poisoning.


dtrer says:

My girlfriend eats on average 8 bananas a day and we have been together for a year. No sign of cardiac arrest!

Monty says:

Why would anyone feel the need to eat 8 bananas a day? Is there no other food available?

Lorenzo says:

Thank you all for posting, I came here concerned, as I have been eating 3 bananas per day. I like to make half of a sandwich using banana with peanut butter (real peanut butter), not brands with corn syrup and such. However, I leave here feeling comfortable that 3 of these wonderfully satisfying treats per day will not harm my physical condition.

Abcedere says:

It’s gotten worse, in a way. Freeze dried bananas! Once you start, you can’t stop! Well, okay–You can stop, because they fill you up. I don’t know if these are new or not. They are new to me. They’re 100% better than fried banana chips

Potassium per 2.5 oz bag is 930 mg.