Types of sweetener

Search the web and you'll find plenty of claims against artificial sweeteners, aspartame in particular. Some state they are responsible for everything from cancer to Alzheimers, though there's little evidence that most cause any harm to people if consumed in moderate amounts.

Safety concerns often originate from research carried out on animals, not people, with dosages many times higher than a human could eat or drink.

Food labels must contain an ingredients list. If sweeteners are used they are listed as "sweetener" followed by its name or food additive code number (see our table).

Acesulphame-K

It has been claimed that acesulphame-K is associated with tumours of the lungs and glands in rats, and with increased cholesterol levels in diabetic rats. But more than 90 studies have verified its safety, and food regulatory authorities have approved it for use.

Aspartame

This has been associated with multiple sclerosis, vision problems, Alzheimer's disease and tumours. However, no clear links have been found and aspartame is recognised as being one of the most thoroughly tested and studied food additives. It is regarded as safe for most people.

People with the rare condition of phenylketonuria should avoid this sweetener. Having phenylketonuria means you are unable to break down phenylalanine, a component of aspartame. All babies are screened for this condition at birth. For this reason, all products containing aspartame will have a warning label.

Cyclamate

Animal studies conducted in the late 1960s suggested cyclamate was carcinogenic. This is no longer considered to be the case and it is approved for use in many countries. However, it remains banned in some, such as the United States.

Saccharin

Although there have been claimed links with bladder cancer, there is no definitive evidence it is carcinogenic.

Sucralose

This is the only sweetener made from sugar. It is chemically altered so can't be digested. Numerous studies verify that sucralose has no carcinogenic, neurologic or reproductive risk.

Alitame, Neotame and Thaumatin

There is no evidence of any harmful effects from these three new sweeteners. In fact, thaumatin has no specified ADI because it is deemed to have such a good safety profile. How safe are they?

Artificial sweeteners provide sweetness without the extra kilojoules of energy that sugar contains. This means they don't contribute to weight gain, and don't feed the bacteria living on our teeth. They're also preferred by many people with diabetes because they have less of an effect than sugar on blood sugar levels.

As with many foods - including sugar - it's not so much what you consume but how much that counts. Nine artificial sweeteners are approved for use in New Zealand: acesulphame-K, alitame, aspartame (aspartame-acesulphame-K), cyclamate, neotame, saccharin, sucralose, and thaumatin.

All are regarded as safe. However, the Australia New Zealand Food Standards Code (the Code) restricts them being added to some foods to ensure consumption from the whole diet doesn't lead to excessive intake.

How much is too much?

Food regulators have set an acceptable daily intake (ADI). This is the amount you could safely consume, per kilogram of your body weight, every day over your lifetime.

A 2003 survey commissioned by Foods Standards Australia New Zealand (FSANZ) found that about 60 percent of us had consumed food or drink containing artificial sweeteners in the previous week. We were most likely to get our sugar-free fix from "diet" soft drinks and confectionery, including chewing gum and chocolate.

The survey found that, almost without exception, we weren't consuming enough artificial sweeteners to pose any risk to our health.

The only concern was over cyclamate. Although average intakes were below the ADI, some people in the 12 to 39 age group exceeded the ADI for cyclamate, mainly from cordials, fruit drinks, soft drinks, and table-top sweeteners. But a 70kg adult would need to drink more than 1.2 litres of cordial or soft drink containing cyclamate every day to reach the ADI.

It's important to remember that consuming more than the ADI over a short period isn't necessarily a health risk, as ADIs have substantial safety margins and are based on a lifetime exposure.

The trouble is it's very hard to know how much you are taking in. Most product labels will tell you which sweetener they contain (either by naming it or giving the additive code number), but they won't tell you how much of it is in the product.

The Code, which controls what goes into food, says artificial sweeteners can only be added in specified amounts or can't be added at all to certain products. In the case of sweeteners, these can only be added in amounts necessary to replace the sweetness normally provided by sugars, or at very low levels as flavour enhancers.

The Code no longer allows table-top sweeteners containing cyclamate, and has lowered the amounts of saccharin and cyclamate allowed in cordials and soft drinks. But there is a loophole in the current regulations. The table-top sweeteners, Sucaryl and Sugromax, have been relabelled as "dietary supplements" permitting them to contain additives not allowed in foods. This means there is no independent scrutiny of their quality and safety because dietary supplements are not regulated in the Code. The Dietary Supplements Regulations is currently being reviewed. This should ensure this loophole is closed.

Is there a cocktail effect?

Increasingly, manufacturers are mixing different sweeteners in the same product to enhance sweetness or make products more heat-stable. For example, Diet Coke contains aspartame and acesulphame-K and Wattie's Lite canned fruit contains saccharin and cyclamate.

Sweeteners are synergistic, which means when they are used together they have more sweetness than if used separately. Therefore less of each sweetener is used.

Also, each artificial sweetener is metabolised differently in the body and combining artificial sweeteners in food products means you are less likely to exceed the ADI for any given sweetener.

Sweeteners compared

Guide to the table 1 Sweetener All sweeteners allowed in the Food Standards Code. Additive code number in brackets.

2 ADI

Acceptable daily intake, in milligrams of sweetener per kilogram of body weight.

3 Sweetness

Sweetness compared to sugar. For example, cyclamate is 30 times sweeter than the same amount of sugar.

4 Found in

Table-top sweeteners and common products which contain this sweetener. Based on our supermarket survey. More products and brands may be available.