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Why is diet cola bad for you?

August 5th 2015 / Peta Bee


Peta Bee can't get enough of the fizzy stuff but why do nutritionists think cola is the Devil?

I love diet cola. I love everything from the moment I hear the pop and fizz of the ring pull to the way the icy cold bubbles gurgle down my throat. I love the immediate lift it gives me and the lingering buzz that follows. Don’t get me wrong, I have made it a once-daily habit because every nutritionist I have met has frowned upon my usage, horrified that I am pouring this caramel-coloured Devil’s liquid down my throat even that often. In truth, though, I could drink more. Much more. It is a guilty pleasure, a habit I can’t - or won’t - break; a sugar fix without the sugar. But I do sometimes wonder what it’s doing to my body - can it really be that bad?

“It’s just rubbish,” says Miguel Toribio-Mateas, chair of the British Association for Nutritional Therapy. “Absolute rubbish.” His viewpoint, it seems, is shared by hoards of nutritionists and scientists who claim diet cola’s image as a healthy alternative to the nine-teaspoons-of sugar, regular variety of the fizzy drink is wholly misplaced. If you think it’s going to help you lose weight, says Toribio-Mateas, you are wrong. Diet cola’s mix of carbonated water, colourings and sweeteners such as aspartame and acesulfame K may combine to less than one calorie, but it can backfire with disastrous consequences not just for your waistline, but your teeth and even the appearance of wrinkles on your face.

A recent study at Purdue University, following 40 years of investigation, reported that fizzy diet drinks may be linked to a range of health problems from obesity to heart disease, just like their sugar-laden counterparts. So what happens? “The fake sugars in the drink are hundreds of times sweeter than sugar and trick your brain into thinking real sugar is on the way,” says Toribio-Mateas. “When the calories don’t arrive, it triggers a cascading effect that interferes with hunger signals, blood sugar levels and satiety.”

MORE GLOSS: Why sugar is the ultimate weight loss enemy

It also confuses your metabolism so that calorie burning becomes harder. Amanda Payne of Switzerland’s Institute of Food, Nutrition and Health published a paper in the journal Obesity Reviews last year which found that consuming large amounts of fructose (a type of sugar), artificial sweeteners, and sugar alcohols (another type of low-calorie sweetener) can all interfere with natural gut bacteria. That, in turn messes up your metabolism and disrupts the body’s way of signaling to you that you’re full and satisfied. As a consequence of all this, the body pumps out insulin, the hormone that controls sugar levels and fat storage, so that you lay down what Toribio-Mateas calls “diet cola belly in the form of more fat around the midriff” - just where you wanted to shed fat.

Amanda Griggs, director of health and nutrition at the Balance Clinic in London, says that “phosphoric acid, the ingredient that gives diet cola its appealing tangy taste and the tingle you get when it is swallowed, can cause a host of problems” - even accelerate the ageing process. In experiments at Harvard University, the mineral, which is widely used in food production was found to make skin and muscles wither and to damage the heart and kidneys over time. Other studies have shown that the phosphorus released from phosphoric acid in just two fizzy drinks a week can cause calcium to be leached from bones, raising the risk of osteoporosis.

Cola (both diet and regular varieties) seems particularly damaging to the skeleton. Typically, a can of diet cola contains 44-62mg of phosphoric acid - more than in many other soft drinks - and researchers at Tufts University in Boston showed that women who regularly drank three or more cans a day had four per cent lower bone mineral density in their hips compared to those who preferred other soft drinks.

MORE GLOSS: 10 bad things you never knew sugar was doing to your body

Then there’s the effect a diet cola habit has on teeth. Sian Porter, spokesperson for the British Dietetic Association says they may lack sugar, but the acidic nature of artificially sweetened fizzy varieties means they still attack tooth enamel. A report in the British Dental Journal a few years ago claimed carbonated drinks were “the biggest factor” in causing tooth erosion in children with any amount of the drinks increasing the risk of rotten teeth in a 14-year-old by 220 per cent. Youngsters who drank more than four cans a day were 500 per cent more likely to suffer dental erosion. “It’s not just the sugary drinks that are causing teeth problems,” says Porter. “Sugar raises the risk of decay, but diet drinks are equally acidic and can cause erosion in the same way.”

What’s certain is that my favourite fizzy drink is no health tonic. It has also been shown to raise the risk of type 2 diabetes and high blood pressure by some researchers. To add to the dire news for diet cola fans, results of a ten year study found a link with cardiovascular disease among those who drank it every day; cola drinkers were found to be 43 per cent more likely to suffer a stroke or heart attack during a ten-year period than those who abstained.

MORE GLOSS: Addicted to the sweet stuff? Here are 10 ways to kick your sugar cravings

So where does that leave me? I was once on the wagon for seven years after a personal trainer convinced me that it was akin to self-poisoning. But I’m off again now and, honestly, am likely to stay that way. Ian Marber, the nutritionist, empathises. He, too, is a secret diet cola addict, sometimes consuming up to three cans a day, although when he exceeds his self-imposed limit he counteracts some of the adverse effects by popping a phosphorous tablet. “I know it’s not good, but, oh, I love the stuff,” he says. “I don’t drink alcohol and don’t smoke, so it’s my single vice. If you like it, I think the key is to make sure it replaces a sugar treat and isn’t taken in addition to a lot of sugar which will just perpetuate the yearning for super-sweet things. I know everything about it is wrong, but I love it.”

Follow us on @getthegloss and Peta @petabeeuk.

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