IT has been said, admittedly on a TV comedy show, that eating more than six bananas at once will kill you.

Karl Pilkington, the grumpy friend of Ricky Gervais and fellow comedian Stephen Merchant, said in Meet Karl Pilkington — An Interview with Ricky Gervais that there was a limit to how much of the fruit you should eat at once.

“Before when you were talking about bananas ... I had that fact, about if you eat more than six, it can kill you,” Pilkington said to Gervais.

“It is a fact. Potassium levels are dangerously high if you have six bananas ... I saw a bowl of bananas. There’s six bananas there. You know why there’s only six? Seven would be dangerous.”

But is that true or an urban myth?

Catherine Collins, a dietitian at St George’s Hospital in London, England, told the BBC that potassium is crucial for survival and can be found “within every single cell of the body,”.

“We use it to help generate an electrical charge which helps the cell function properly. It helps keep your heart rate steady, it helps trigger insulin release from the pancreas to help control blood sugars, and more importantly keeps blood pressure in check.”

Small degree of (dietetic) satisfaction that people more interested in bananas than @jeremycorbyn at the moment pic.twitter.com/k9XheI89Sy — Catherine Collins (@RD_Catherine) September 13, 2015

If the potassium level in the body is too low or too high it can cause an irregular heartbeat, stomach pain, nausea and diarrhoea. Potassium chloride used in lethal injections in the US, as extremely high doses can cause cardiac arrest.

However, Collins said “it would be impossible to overdose on bananas.”

“You would probably need around 400 bananas a day to build up the kind of potassium levels that would cause your heart to stop beating ... Bananas are not dangerous — and in fact they are, and always have been, very good for you.”

The Australian Government states that adult men should consume 3,800mg of potassium daily and women should intake 2,800mg per day.

An average banana, weighing 125g, contains 450mg of potassium, meaning a healthy male can consume at least eight bananas before reaching the recommended level.

Collins said people with kidney disease should steer clear of foods that are high in potassium.

“These patients have a very low kidney function which can potentially see a build-up of harmful potassium levels in their blood stream because they can’t get rid of the mineral when they pass urine,” she told the BBC. “So in theory it is possible for someone with kidney disease to die of a high blood potassium level if they decided to consume lots of different food types rich in the mineral.”