The average Aussie drinks 100 litres of this a year - and it's killing us

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UPDATE: A new study suggests artificial sweeteners used in ‘diet’ soft drinks are contributing to a rise in diabetes. The study goes some way to answering a question that has been on a lot of peoples’ minds: “Is Diet Coke bad for you?”

According to Israel-based researchers, non-caloric sweeteners like saccharin, aspartame and sucralose can disrupt healthy microbes that live in the gut. This may cause blood sugar levels to rise, which can lead to diabetes. “Non-caloric artificial sweeteners may have directly contributed to enhancing the exact epidemic that they themselves were intended to fight,” the authors write in the journal Nature.

We previously reported: Let’s talk straight: soft drinks aren’t great for your health.

You know that, we know that, your neighbour knows that. And yet the message seems to be falling on deaf (or more likely, stubborn) ears because Australians consume 100 litres of the fizzy stuff every year, per person.

Of course, it’s important to treat yourself sometimes – but it’s equally important to understand that the health effects of soft drinks are far more long-lasting, and potentially serious, than the temporary sugar high they deliver.

One look at news headlines from the past couple of years suggests soft drinks are fast becoming the new cigarettes. Last year, former New York mayor Michael Bloomberg campaigned for a city-wide ban on soft drinks larger than 16 ounces (roughly 500mL), which was eventually knocked back. Here in Australia, the ACT government banned the sale of soft drinks in the territory’s primary schools earlier this year, and there have been numerous calls for similar crackdowns around the country.

The Glow spoke to a dentist, doctor, psychologist and dietician to find out exactly how harmful Coke and co. are for you.

Doctor

Surprise, surprise - a soft drink a day won’t keep the doctor away. You may get a short-term kick, but in the long run soft drink can lead to numerous diseases and even early death, says Professor Merlin Thomas from the Baker IDI Heart and Diabetes Institute.

Firstly, the sugars in soft drinks are absorbed quickly, meaning your body has to work just as fast to store them. The extra demands this places on your pancreas are believed to contribute to “early burnout”, which can lead to diabetes. This fast response also causes your sugar high to fade quickly, leaving you hungry and more likely to snack.

Regular soft drink consumption thickens your waistline (up to 7kg per year if you drink a can a day), but it can have the opposite effect on your bones. This is bad news for women, who are prone to fractures and osteoporosis. Professor Thomas says this thinning could be caused by the phosphoric acid in soft drink, or the fact it’s often consumed in place of bone-friendly drinks like milk.

In addition to sugar, some soft drinks contain substances like caffeine, which is addictive, can increase blood pressure and stiffen arteries; and carnitine, which has been linked to heart disease.

Professor Thomas says the first step to reducing the impact of soft drinks is a personal one: “When everyone commits to looking after their health, soft drinks will not be the menu."

Dentist

Two processes happen almost immediately after soft drink comes into contact with your teeth.

Firstly, the bacteria on your teeth - plaque - will start using the sugar to produce acid. "This acid will then begin the process of tooth decay with a process called demineralisation - the removal of minerals from the tooth’s surface," explains Professor Mike Morgan from the University of Melbourne.

The second process involves the acid that's already present in the soft drink - yep, that includes sugar-free varieties - which can start eroding the tooth enamel.

In the long term, regularly drinking soft drinks can produce more serious side-effects. "In the absence of anything that's going to help ... it could lead to the production of a cavity that can get larger and larger and eventually cause pain if left to its own devices," says Professor Morgan.

Aside from drinking less of it, there are several things you can do to counteract soft drink's dental impacts - for instance, reduce the amount of contact it has with your teeth by drinking with a straw, and then rinsing your mouth with water afterwards.

"Brushing twice a day with that, drinking fluoridated water and maintaining a sensible diet which is low in sugar will increase the chances of having good oral health," says Professor Morgan. "95% of Australians have access to fluoridated water - it's the best public health activity we have in reducing dental decay."

Nutritionist

Drinking just one can of soft drink knocks over your recommended daily amount of added sugars in a matter of minutes (or seconds, depending on how thirsty you are). Right away, your body and bloodstream is slammed with a high dose of glucose, calories, carbohydrates and sugar - and because soft drink isn't as filling as solid foods, it adds a lot of extra calories to your lunch or afternoon snack without you noticing. Sneaky.

The effects don't end with your sugar hit, though. Numerous studies show that your soft drink habit can have serious long-term impacts on your body, including gradual weight gain and a higher likelihood of developing diabetes and heart disease.

"Research suggests even one can of soft drink a day is linked with high rates of obesity," says Associate Professor Tim Crowe from Deakin University's School of Exercise and Nutrition Sciences.

Happily, there's good news here. Although it seems like eye-rollingly obvious advice, simply swapping your can of Coke for a glass of water can help to reverse weight gain.

"Clinical studies have shown really clearly that when people switch from soft drinks to water, on average they'll lose weight," says Professor Crowe.

Psychologist

Soft drinks don’t only affect your weight and teeth.

Dr Kieron Rooney and Professor Bob Boakes, from Sydney University’s Faculty of Health Sciences and School of Psychology, have completed a series of experiments using rats to assess the metabolic and behavioural impacts of sugar-sweetened beverages. In their tests, the rats are given either 24-hour access, or two hours access per day, to water containing dissolved sugar over a number of weeks, along with their normal food and water.

The findings have been, frankly, a little scary. Four weeks in, rats with 24-hour sugar water access had far more abdominal fat than the ones that only consumed water – and their livers had become fatty and had impaired glucose tolerance. The sugar also hindered their memories.

“After just 18 days of unlimited access to a sugar drink, rats were impaired on a short-term memory test … they were worse at remembering where an object had recently been located than control rats,” Dr Rooney explains. It’s important to note the average human likely doesn’t gain 40% of their total daily energy from sugary beverages, as the test rats did.

Only a few tests have examined these health impacts on human participants under well-controlled conditions. A Danish study of healthy young adults found drinking just one can of sugary drink per day caused metabolic deterioration after six months.

So what should you do with that soft drink you suddenly don't feel like drinking any more? You could flush it down the toilet - no, seriously, watch this: