ISLAMABAD: Mother always said not to eat before swimming. But is the old wives tale actually true?
 
Eating before taking a dip could trigger nausea and reflex, one expert warns.
 
And while fizzy water contains no sugar or calories, it contains acid that may erode tooth enamel.
 
From why we crave dessert to tips for banishing garlic breath, here, experts answer the most curious health questions..
 
Fizzy: Sparkling water is made by dissolving carbon dioxide in water, which creates an enamel-eroding acid
 
While plain fizzy water contains no calories or sugar, it may harm our teeth.
 
This is because it's made by dissolving carbon dioxide in water, which creates carbonic acid.
 
And this acid, like the acid in other fizzy drinks, erodes tooth enamel, says Professor Andrew Eder of University College London's Eastman Dental Institute. 
 
'Even one glass can cause microscopic levels of the outer surface of the enamel to dissolve, and when we consume something acidic the mouth stays acidic for 45 minutes before returning to a normal pH level,' he says.
 
But you'd need to drink sparkling water daily basis for years to suffer the effect — one or two glasses a week won't hurt.
 
However, with flavoured fizzy drinks not only is there a risk of erosion but they also contain sugar or sweeteners, some of which can lead to tooth decay.
 
With any fizzy drink, Professor Eder suggests minimising the effects by drinking through a straw to avoid contact with teeth, or drinking it in one go.
 
'If you sip it, the mouth stays acidic for longer.' Having it with food also helps, as it will make the mouth less acidic. 
Should you swim after eating?
 
It's the sort of thing your mother used to say — don't swim too soon after eating or you'll drown.
 
There's no reason that you would — however, going for a dip after eating could trigger nausea and acid reflux in susceptible people, says Kathryn Brown, a senior performance nutritionist for British swimming at the English Institute of Sport.
 
Cooling: Going for a dip after eating could trigger nausea and acid reflux in some people, one expert warns
 
This is because being in the horizontal position allows acid to escape from the stomach and go back up the oesophagus, causing heartburn. 
 
'It's down to individual tolerance, but sports nutritionists generally advise waiting two to four hours after a large meal, or up to one hour after a light snack before swimming,' says Kathryn.