Diet cola myths exposed

Will it really help you lose weight, or protect your teeth?
Learn more
  • Updated:16 Mar 2007

01 .Myths

Diet cola

In brief

  • If you drink diet cola our taste test suggests you might enjoy one of the cheaper brands as much as the heavily promoted big names.
  • Diet cola might not be as helpful in the fight against flab as you’d think, kids risk overdosing on the artificial sweeteners, and it’s still harmful for your teeth.

If you drink diet cola, chances are it's to avoid the sugar in the regular version, perhaps to help you lose weight or for the sake of your teeth. But there are a few things you might believe about diet cola that don't stand up in reality.

Please note: this information was current as of March 2007 but is still a useful guide today.

Myth 1: Big-name diet colas taste better

Last year Coca-Cola Amatil spent more than $18 million on promoting Coke Zero alone. And these big corporations aren't wasting their money - if you enjoy a diet cola, chances are you'll grab a Diet Coke or a Pepsi Max. But there are much cheaper brands of diet cola in the supermarkets and chain stores.

Diet cola taste test

To find out if the big brands really taste better we asked a few hundred consumers at a Sydney shopping centre to taste and rate 11 brands of diet cola. The brands were:

  • Australia's Choice Diet Cola (KMart)
  • Black & Gold Diet Cola (IGA)
  • Classic Taste Diet Cola (Aldi)
  • Coca-Cola Zero
  • Diet Coke
  • Home Brand Diet Cola (Woolworths)
  • LA Diet Ice Cola
  • LA Maxi Ice Cola
  • Pepsi Light
  • Pepsi Max
  • You'll Love Coles Diet Cola (Coles)

No clear favourites

The colas were identified only by code numbers so the tasters didn't know which brands they were tasting. We recruited 277 tasters who said they regularly drink diet cola - 40% of them male, and 42% of them aged between 10 and 18. Each tasted four colas and rated them on a five-point scale to indicate how much they liked the taste.

Overall the tasters liked no one brand more or less than average. And it was the same when we separated the results for adults and young people under 18 - neither group had any clear favourites.

The manufacturers of Coke and Pepsi pass on their huge marketing budgets to consumers as higher prices. So why not ignore the ads and try the cheaper alternatives? You'll save money, and you might find a drink you enjoy just as much.

Myth 2: Caffeine makes cola taste better

All the drinks in our test contain caffeine. Soft drink manufacturers claim it has a distinctive taste that heightens the flavour, but recently published research suggests this is untrue.

Expert tasters were unable to distinguish between caffeine-free Coca-Cola and the same drink spiked with caffeine at the level usually added to cola drinks.

This suggests adding caffeine could have more to do with its mildly addictive properties than its taste.

Myth 3: Diet colas help you lose weight

A can of regular Coca-Cola contains about eight teaspoons of sugar and gives you 675 flab-forming kilojoules. If you drink a can of diet cola instead you'll get less than 10 kJ.

Some studies have shown people lose weight if they substitute diet soft drinks for sugary ones.

However, evidence is emerging that even artificially sweetened drinks can stimulate your appetite; they can give you more of a craving for sweet foods and so contribute indirectly to you putting on weight.

You’re more likely to lose weight if you avoid these drinks altogether — maybe drink water, or get your caffeine fix from a cup of coffee?

Myth 4: Diet cola drinks are safe for teeth

Diet colas don't contain sugars that cause tooth decay but they contain phosphoric acid (and sometimes citric acid as well).

These acids can cause erosion in teeth, a condition where enamel is dissolved from tooth surfaces. It's different from decay, but can be just as bad for your teeth.


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02.Artificial sweeteners


What sweeteners are used?

The diet colas in our test contain no sugar but they’re sweetened with artificial sweeteners. Drinks usually contain at least two sweeteners because manufacturers have found that combinations give a quality of sweetness that’s more like sugar than any one sweetener on its own.

You can identify the sweeteners from the code numbers on the label:

  • Acesulphame potassium (950)
  • Aspartame (951)
  • Cyclamate (952)
  • Saccharin (954)
  • Sucralose (955)

These substances can be many hundreds of times sweeter than sugar so the amounts you get in your drink are very small.

Are they safe?

  • There have been reports linking many of these artificial sweeteners to increased risk of cancer. In the 1970s several studies of rats fed very large amounts of saccharin raised concerns about its safety, and as a result it was banned in Canada and until 1996 products containing saccharin in the USA had to be labelled with a warning.
  • It was much the same with cyclamate. A study found that it increased the risk of bladder cancer in rats and as a result its use was banned in Canada and the USA, and in the UK it was banned until 1996.
  • And aspartame has been linked to a variety of health problems ranging from Gulf War Syndrome to increased risk of brain and breast cancers.
  • But most of these claims for the various sweeteners have failed to stand up conclusively to rigorous scientific examination. Last year, for example, a European report claimed aspartame causes a number of different cancers, whereas an independent panel of experts looking at the same research results found no compelling evidence for aspartame being harmful at the levels permitted in foods and drinks.
    With these controversies widely reported in the media it’s not surprising that a quarter of adult Australians now believe artificial sweeteners cause cancer. Experts, though, are generally convinced that any risks are small. And you have to balance these small risks against the very substantial risks to your health from being overweight.

As long as there’s no absolute certainty, experts recommend we limit our intake of artificially sweetened foods and drinks. Recent surveys have found that some consumers (mainly children) are now exceeding the acceptable daily intake (ADI) for cyclamate. The ADI is the ‘safe’ level recommended by scientific experts; there’s a substantial safety margin and consuming more than the ADI over a short period isn’t necessarily a health risk, but on a regular basis there might be cause for concern.

“Contains phenylalanine”

You’ll see this warning on any product sweetened with aspartame.

When aspartame breaks down in the body, one of the products is the amino acid phenylalanine. This is a health hazard for people born with the rare hereditary disease phenylketonuria (PKU). Their bodies have a problem breaking down phenylalanine, so it builds up in the blood to levels that can cause brain damage.

To prevent this from happening they have to limit their intake of phenylalanine from all sources, including common protein foods such as meat and milk.

Chance discovery

Some artificial sweeteners were discovered by chance — or sloppy laboratory practices.

  • Ira Remsen, one of the discoverers of saccharin (in 1879), was working on the chemistry of compounds made from coal tar, but noticed a sweet taste after not thoroughly washing his hands before dinner.
  • Michael Sveda was developing an anti-fever drug when he discovered cyclamate. He was a smoker and noticed a sweet taste after momentarily putting his cigarette down on the lab bench.