25 Apr 2016  •  Dental Health  •  5min read By  • Jo Dickinson

How bananas could make a monkey of your teeth!

I once spent some time with some cyclists. It was an eye-opening experience, because without a doubt they took their sport really seriously, more seriously than any other amateur sport that I have come across. I quickly concluded that any man who shaves his legs and plunges into a bathtub full of ice after a ride is either incredibly committed or perhaps just simply a little deranged!

Some of the group were professional cyclists, worshipping their bodies by only eating healthy nutritious food. They were incredibly knowledgeable and kept up-to-date with the latest theories in sport science. I really admired their dedication. However, I did have one bugbear and that was their excessive consumption of bananas. I’m not suggesting that bananas aren’t packed full of vitamins and minerals, but they also have the potential to harm a really important part of the body – our teeth.

Potassium is one mineral that is lost during perspiration, especially during exercise. Bananas contain high levels of potassium so snacking on them is a good way to replenish the potassium used up during exercise. They also contain Vitamin B6, magnesium and other micronutrients vital for a healthy body.

The cyclists’ banana obsession involved eating bananas frequently throughout their ride, which could easily last up to six hours or more. The idea behind it was in fact based on science, a particularly interesting study that had been carried out in the US, looking at various ways of improving cyclists’ performance. In this study, one group were given a sugary drink during their ride and the other group were given bananas. Unsurprisingly, the banana-fuelled group did significantly better than the sugar group in terms of performance and tissue recovery.

So, why do I have reservations about excessive consumption of bananas?

Well, there is a very interesting case report from North Carolina School of Dentistry which was created in the 1980s about a three and a half year old boy who had been given pieces of banana to suckle on instead of a dummy. These bananas had caused every tooth in his mouth to rot down to the gum line in just over two years. This was a really rare case and unlikely to be seen again, but it did demonstrate that bananas do contain sugar and can have an impact on the teeth. I am not suggesting that snacking on the odd banana will cause this level of destruction; frankly it won’t. Eaten in moderation, bananas are still on the tooth friendly-ish list.

These bananas had caused every tooth in his mouth to rot down to the gum line in just over two years.

Bananas contain surprisingly high levels of nasty sugars – the type that rots teeth. A banana contains glucose, fructose and sucrose in levels high enough to cause tooth decay. In 1990, a very reliable study looked at the sugar content and stickiness of various snacks and concluded that bananas, raisins and crisps could all contribute to the decay process.

Aristotle hypothesised that eating figs that stuck to the teeth caused dental decay. He was probably right. If only this great philosopher had also been able to conclude that snacking on nuts or cheese was a safer alternative, he could have saved generations from the pain of tooth decay.

It can take the mouth anything up to an hour to recover after eating sweet food. Saliva cleanses away food particles and slowly replenishes minerals lost from the enamel surface. Within my group of cycling friends, they were eating bananas so often; their mouths were not really being given the chance to recover before eating another, leaving them at high risk of decay.

Going bananas!

Even Paignton Zoo in Devon is concerned about the sugar content of bananas and in 2014 stopped feeding them to their monkeys! They felt that the bananas grown for human consumption are too sugary and bear little resemblance to the wild bananas that monkeys would eat in their natural habitat. They discovered the monkeys became really naughty when they had too much sugar and now they are looking for a supplier who can provide bananas with a low sugar content – so it’s not just us who suffer the pain of cutting down on our banana intake!

Of course, fruit is such an important part of our diet and shouldn’t be reduced unless it really is being eaten in excess. However, there are ways of eating fruit without damaging our teeth. Bearing in mind that many fruits also contain high levels of acid which can also damage teeth; problems arise as a result of snacking on fruit regularly, so eating it at mealtimes and opting for something more tooth-friendly between meals is the healthiest thing to do.

Of course, fruit is such an important part of our diet and shouldn’t be reduced unless it really is being eaten in excess.

Sometimes, dedicated sports people don’t have this option. The alternative to bananas for my friends was constantly sipping on sugary drinks, which is just as bad. Maybe their solution lies in using fluoridated oral products to reduce the effect of the constant influx of sugars over their teeth. Perhaps part of the holistic health regime of a serious sports person should include a trip to the dental practice to discuss the best means of protecting teeth during high-level training. Our bodies are a temple, lycra clad or not. The gateway to this temple is the mouth and our teeth are such an important part of our bodies that we often overlook. Holistic health and fitness should include our teeth and gums.


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