Maysie Strang caused some excitement in the media recently when she reached the age of 102 despite a lifetime of heavy smoking. Maysie started as a teenager and smoked 20 a day. Her son Sandy, 65, says: “The house was a fug of smoke. She was a secretary and was always smoking at her typewriter.”

But that story – the ‘ultimate health paradox’, as Sandy describes it – overshadowed what might otherwise have been trumpeted as Maysie’s unusual longevity secret: bananas. Sandy said: “She’s mad on bananas. When she was working at the newspaper [Maysie was at the Daily Express] she was often eating lunch on the hoof, so she used to have a banana. She is a fanatical banana eater, she still eats a couple a day.”

Maysie is not the first centenarian to have their longevity associated with bananas. Salustiano Sanchez-Blazquez, who at 112 died in New York as the world’s oldest man, also put his long life down to bananas (and aspirin).

So could there be anything in it?

Plausibility rating: 7 out of 10. Oddly enough, yes. Bananas have got lots of things going for them and in particular their high level of potassium. Why does this matter? Well, there is good evidence that potassium can help counter the effects of too much salt in our diets, something that affects an awful lot of us and can lead to problems with our hearts.

First the basics. As well as potassium, bananas contribute to your recommended daily intake of vitamin B6, vitamin C, magnesium, copper and manganese. They are rich in fibre and contain virtually no fat. An average one has around 100 calories. And in the UK we love them, with the typical person eating around two a week.

But perhaps we should be eating more because many of us still don’t get enough potassium. That’s a problem when combined with another common trait in Western diets: eating too much salt. There is now strong evidence that a diet which is low in potassium and high in salt significantly increases our risk of cardiovascular problems like stroke and heart disease.

A change of diet might be the answer. This study, for example, suggests that eating twice as much potassium as sodium (i.e. a ratio of 2:1) halves your chance of dying from cardiovascular disease. The bad news is that just 1.5% of the US population (and probably similar levels of the UK population) currently eats a diet with that ratio. The authors say that ‘extraordinary efforts’ will be needed to achieve it for the whole population.

Eating a couple of bananas a day, like Maysie, as part of a balanced diet would be a start. Each banana has around 425mg of potassium which is around 15% of the amount recommended by the World Health Organisation. Other good sources are baked potatoes, tomatoes, milk, sweet potatoes, raisins and avocados. You can even find potassium in fudge and chocolate, though there are other reasons why you might not want to increase your consumption of those.

So Maysie may have science on here side. You would want to avoid her smoking though. While we can’t know for sure, it’s likely that Maysie has the set of genes that help protect some people from the effects of smoking and drinking. You may not be so lucky.

photo credit: Chris B Richmond http://www.flickr.com/photos/35652152@N07/28004881235″>Bunches of Bananas via photopin(license)