How do you get rid of garlic breath? Why do our stomachs rumble? And IS sparkling water bad for you? Here, experts explain the truth behind common food myths...

Fizzy: Sparkling water is made by dissolving carbon dioxide in water, which creates an enamel-eroding acid Is sparkling water bad for you?
  • Fizzy water contains carbonic acid which erodes away enamel in teeth
  • Swimming after eating could actually trigger nausea and acid reflux
  • People are biologically driven to crave sweets after a savoury meal
  • Ice cream cannot cool a person down, in fact metabolising it releases heat

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

Is sparkling water bad for you?

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

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.

She adds that if you know you're going swimming soon, but need to eat something, have a light meal — avoiding high intakes of fibre, fat and protein, because these are all digested slowly and stay in the stomach for longer, so are more likely to cause stomach discomfort and nausea if you exercise before they have passed through the stomach.

Mouldy: Foods go fizzy when they go off due to gas

Mouldy: Foods go fizzy when they go off due to gas

Why do foods go fizzy when they go off?

Different foods go off in different ways, partly depending on what's in them. 

The fizziness is the result of gas produced by certain foods when they go off — other foods become stale or discoloured.

'Some foods contain small amounts of certain bacteria or yeasts that produce gases such as carbon dioxide or hydrogen over time — and the fizzy taste,' says Peter Wareing, principal food safety adviser at research firm Leatherhead Food International. 

This is most common in foods that also contain a lot of water, such as ready meals (to make the ingredients easier to chew), and in foods such as yogurt (which contain bacteria).

Food manufacturers try to reduce the amount of bacteria in foods by cooking them at certain temperatures, or by adding salt to kill them off.

Why do I crave sweets after a meal?

Fancying a pudding after a meal is not simple greed; you are biologically driven to it by the need for a balanced diet.

This is 'sensory specific satiety', where too much of one type of food makes you want something different.

Dr Denise Robertson, senior lecturer in nutritional physiology at the University of Surrey, says: 'Continued consumption of a food results in a reduced liking for that and eventually you stop eating it.

'At the same time you experience an increased desire to eat a food that is completely different.'

Sweet treats: We are biologically driven to crave dessert after a savoury meal in order to get a balanced diet

Sweet treats: We are biologically driven to crave dessert after a savoury meal in order to get a balanced diet

It's all down to evolution; eating only one type of food would soon cause malnutrition, so we developed a mechanism that tells us to eat something else. 

This is why it is easy to overeat at all-you-can-eat buffets — because we eat many types of food at once, we don't feel full so quickly.

'If you only eat something sweet, you will want something savoury instead,' says Dr Robertson.

How do I get rid of garlic breath?

Garlic breath is caused by compounds containing sulphur, which the body cannot digest — these are excreted through breath and sweat instead. 

The best way to get rid of it is to eat an apple, research from Ohio State University has found.

Scientists tested how different foods affected levels of sulphur compounds after eating raw garlic — raw apple had the most powerful neutralising effect.

Bad breath: Garlic breath is caused by compounds containing sulphur, which the body cannot digest

Bad breath: Garlic breath is caused by compounds containing sulphur, which the body cannot digest

An enzyme in apples is thought to react with the garlic compounds, breaking them down and removing odour. 

Green tea, spinach, parsley and fresh mint were also found to have neutralising effects, possibly as they're rich in polyphenols, an antioxidant, which break down the compounds.

Previously, Ohio State University found milk can halve breath concentration of one of the main odour-causing compounds, allyl methyl sulphide. Full-fat milk was more powerful.

For best effects, eat the foods at the same time as the garlic, says Professor Sheryl Barringer, who oversaw both studies.

If you are going to skip a meal, which is the best one to miss out?

Many people do this as a way to lose weight, but missing meals can make things worse, suggests Priya Tew from the British Dietetic Association.

'Our bodies become accustomed to regular food intake and organise hormone release accordingly. 

Suddenly, skipping a meal can lead to low blood sugar levels, then when you eat again, larger fluctuations in the hormone insulin and blood sugar, which could be setting you up for fat gain instead of fat loss.' 

Skipping lunch: Studies have shown  missing meals leads to weight gain around the belly, experts warn

Skipping lunch: Studies have shown missing meals leads to weight gain around the belly, experts warn

But if you are going to miss a meal, you could choose lunch because, being in the middle of the day, it's more likely that you will be snacking instead, which could help avoid the sugar slump, she says.

Three regular meals stop sugar levels dropping too low, so you're less likely to have cravings for sugary, more calorific foods, too.

A recent study suggested skipping meals leads to weight gain around the belly, and the development of insulin resistance, meaning diabetes is more likely, according to The Journal of Nutritional Biochemistry. 

Why does my tummy rumble?

That 'rumbling' sound is caused by gas bubbling through liquid as it is propelled by contractions through different parts of your digestive system, says gastroenterologist Dr Nick Read, chief medical adviser for charity The IBS Network.

The loudest rumbles come from the stomach and colon.

Gas in the colon is a mix of hydrogen, methane and carbon dioxide, generated from the fermentation of food that hasn't been completely digested in the small intestine.

Rumbling: Our stomachs make a sound when we are hungry but also when we are upset or worried

Rumbling: Our stomachs make a sound when we are hungry but also when we are upset or worried

The liquid is a mixture of digestive secretions, drinks and partly broken down food.

This rumbling typically occurs when we're hungry — the thought of eating makes the stomach secrete acid and contract in anticipation of a meal.

But hunger is not the only cause.

'Often people's stomachs rumble because they are upset or worried, so it is expressed instead by the gut,' says Dr Read.

Can cold food really cool us down?

When the weather gets warmer, we are naturally drawn towards eating cold food such as ice cream.

Icy: Even cold food makes heat when broken down

Icy: Even cold food makes heat when broken down

But there's no evidence to suggest food can cool us down, says Professor Susan Lanham-New, head of Nutritional Sciences at the University of Surrey.

'Any food will need to be broken down and metabolised, and these processes will give off some heat, which makes you feel slightly hotter,' she says. 

'The process that makes us cool down is heat dissipation, where a raised body temperature makes the brain send a signal to activate mechanisms, such as sweating, to get the body temperature back to its base level.'

The most important thing when feeling hot is to drink plenty of water, as this will replenish fluids lost through sweating.

Why do I want to be sick when I see something unpleasant?

That visceral feeling of disgust is the body's way of avoiding something harmful. 

It harks back to when much of our available food was rancid, says Richard Clarke, a neuroscientist at University College London.

When the brain receives a visual clue that something could be toxic — such as rotting meat — it messages the vomiting centre at the bottom of the brain. 

This sends signals to the body to co-ordinate the actions needed for vomiting.

Dr Clarke explains: 'The stomach muscles relax, you produce a lot of saliva and your vocal cords tighten to stop stomach acid getting to the lungs. 

'If you stimulate the vomiting centre enough, it sets off a cascade of reflexes that actually make you vomit: the diaphragm contracts rapidly and the abdominal muscles contract to squeeze the stomach.' 

Vomit-inducing: Wanting to be sick after seeing something disgusting is an adaptation to keep us from danger

Vomit-inducing: Wanting to be sick after seeing something disgusting is an adaptation to keep us from danger

This reflex would have evolved through natural selection, adds Adam Perkins, a lecturer in the neurobiology of personality at King's College London. 

Those who experienced revulsion at rotting meat were more likely to survive, so the reflex spread.

Dr Clarke adds: 'As our brains evolved they encountered new concepts, such as betrayal. 

'Older areas of the brain, such as the one governing disgust response, were brought in to deal with these. So you can feel physically sick when you hear about a moral transgression.'

Salty: Unprocessed salt is no better than processed

Salty: Unprocessed salt is no better than processed

Is unprocessed salt better?

Most table salt is mined from underground salt deposits and then heavily processed to remove impurities — but this doesn't mean 'unprocessed' salt such as sea salt flakes is any better for you.

Sea salt comes from evaporated sea water and it is less refined, so it often contains traces of other minerals, such as calcium or iron, depending on where the water came from.

'However, if you're sticking to a sensible amount of salt (the maximum is 6g a day for adults), these traces wouldn't be enough to make any difference to your health,' says Sian Porter of the British Dietetic Association.

'Some table salt, on the other hand, has iodine added, which is important for thyroid hormones.' 

This would usually be described as 'iodised salt' on packaging.

Crucially, she says, table salt and sea salt have the same amount of sodium — and this is what we need to watch, as too much can raise blood pressure.

'The argument that's sometimes put forward is that sea salt has larger crystals and some varieties are flavoured, so you may use less,' she says.

'However, the best advice is to add little or none of either type to your cooking and don't add it without tasting your food first.'

 

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By Mathias Dillion 10/13/2015 14:14:00