Taking the fizz out of diet soda

Calorie-free, artificially sweetened drinks are not necessarily the healthier choice.

Research findings published earlier this month reported that drinking just one sugar-sweetened beverage a day, such as a fizzy drink, could increase a man's risk of heart attack by 20 per cent.

The study, published in the journal Circulation, followed more than 40,000 men for 22 years and found that sugar-sweetened beverages had a harmful effect even after researchers accounted for differences in age, physical activity, family history of heart disease and diet quality.

It comes as no surprise that sugar-sweetened beverages are detrimental to our health. After all, a single can of soda can have upwards of 180 calories and a whopping 12 teaspoons of refined sugar.

If you've ditched regular soda in favour of diet soda assuming it's a healthier choice, you may want to think again. Research suggests that diet soda isn't all it's cracked up to be, and may in fact have some potential health risks of its own. Here are five reasons to rethink your diet soda consumption.

1 Diet soda tied to heart attack and stroke

A study released earlier this year in the Journal of General Internal Medicine followed more than 2,500 adults for 10 years and found that people who drank at least one diet soda a day were 43 per cent more likely to have a heart attack or stroke compared with those who didn't consume fizzy drinks on a daily basis. The results held true even after researchers accounted for differences in physical activity, body mass index and whether or not participants had diabetes and heart disease.

2 Diet soda may decrease bone mineral density

Results from the Framingham Osteoporosis Study, published in The American Journal of Clinical Nutrition in 2006, found that women who drank the most cola, either regular or diet, had significantly decreased bone mineral density compared with women who reported having less than one cola per month. Even after adjusting for variables such as calcium and vitamin D intake, researchers found that the more cola a woman drank, the lower her bone mineral density.

While the exact cause isn't clear, researchers suggest that phosphoric acid, a common flavour enhancer found in cola, may leach calcium from the bones resulting in reduced bone mineral density.

Emilie Hartmann, a registered dietitian at EHL Dubai Mall Medical Centre, warns that soda can also displace healthy beverages from the diet. "One of the health risks I see related to the consumption of diet soda is that it is usually consumed instead of more nutrient-rich drinks, such as milk, which is high in calcium," she says.

3 Diet soda linked to metabolic syndrome

Numerous studies have shown that diet soda may increase the risk of metabolic syndrome, a cluster of symptoms that includes increased waist circumference, high blood pressure and high cholesterol levels, which together increase the risk of type 2 diabetes and heart disease.

One study, published in the journal Circulation in 2008, found that the risk of developing metabolic syndrome was 34 per cent higher in people who drank the most diet soda, compared to people who drank the least. Interestingly, the risk for metabolic syndrome was higher in people who drank diet soda, compared to regular soda.

4 Diet soda linked to type 2 diabetes

When asked about the health risks of diet soda, Sara Ismail, a clinical dietician at Advanced Cure Diagnostic Center in Abu Dhabi, warns against its potential link to diabetes. "In 2009, the journal Diabetes Care published a study that associated daily diet soda consumption with significantly greater risks of weight gain, impaired glucose control and eventual diabetes," she says.

In fact, the study found that people who drank diet soda at least once a day had a 67 per cent higher chance of developing type 2 diabetes, compared to people who did not drink diet soda.

5 Diet soda associated with obesity

A study presented at the annual meeting of the American Diabetes Association in 2005 surprised many health experts when it was revealed that diet soda drinkers were more likely to be overweight and obese than regular soda drinkers. Researchers reported that over the eight-year study period, drinking one to two cans of diet soda every day increased the risk of becoming overweight by 55 per cent, compared to just 33 per cent for the same amount of regular soda.

The bottom line

It's important to note that while all these studies show an association, they do not show a direct cause-and-effect relationship. In some cases, people who drink diet soda have other diet and lifestyle behaviours that may affect their health, and these are not always accounted for in research studies. Health experts agree that more research is needed to fully understand the long-term health effects of diet soda. One thing can't be denied - diet soda remains a highly processed beverage and, like regular soda, should be consumed in moderation. "I like to remind my patients that diet soda is calorie-free, which is positive, but it is also nutrient-free, unfortunately," says Hartmann.

Michelle Gelok is a member of the Dieticians of Canada and holds a BSc in Food and Nutrition. She lives in Abu Dhabi.

Did you know?

- Most diet soda gets its sweet taste from artificial sweeteners - synthetic sugar substitutes that are up to 13,000 times sweeter than sugar.

- Some brands of diet soda contain phenylalanine, an amino acid found in the artificial sweetener aspartame. Phenylalanine is very dangerous for people with a rare genetic disorder called phenylketonuria (PKU) because their bodies cannot break it down, resulting in dangerously high levels in the body.

- Earlier this month two leading cola companies changed the way they make the caramel colouring used in their soft drinks available in California to avoid putting a cancer warning on their labels. The change comes on the heels of a new law in the state that aims to limit people's exposure to toxic chemicals that might cause cancer.