Healthy Food

Artificial sweeteners: How safe are they?

Much has been written about the perils of eating sugar, now linked to just about everything from diabetes and obesity, to less obvious heart disease and skin ageing. So are synthetic chemical sweeteners the answer? In her best-selling Quick Guide to Detox, available as a revised and updated e-book, Liz explains how to choose the best artificial sweeteners – both plant-based and synthetic.

What are the best artificial sweeteners?

Sugar alternatives have been sold to us for decades in an attempt to feed our naturally sweet tooth with a low-calorie alternative. Over the years, many have been linked to significant (and potentially serious) side-effects. Here’s the low-down on getting a sugar high…

Aspartame (NutraSweet, Equal, Canderel, Spoonful, AminoSweet)

Aspartame has 4 calories per gram (but is 200 times sweeter than sugar, so only tiny traces are used). It is technically a methyl ester of the aspartic acid/phenylalanine dipeptide – a synthetic chemical used as a sugar substitute even in non-diet processed foods as it is cheaper than real sugar. It is easy to find on labels as it must be avoided by those with the genetic condition phenylketonuria (PKU) and so is always clearly labelled.

Of all the artificial sweeteners, aspartame has probably attracted the most controversy. Much has been written about its possible link with brain disorders, mood swings, aggression and ADHD (especially in children and young people who drink ‘diet’ drinks), headaches and actually causing increased appetite (bad news for dieters), however a European Food Safety Authority review in 2013 did conclude it was safe for human consumption.


At 1.6 calories per gram, mannitol is made from sugar alcohol, usually derived from GM-corn syrup. Considered to be one of the safer synthetic options (alongside sorbitol), it is absorbed relatively slowly by the body and has few adverse side effects aside from a laxative action when consumed in great quantity. Mannitol can be used for baking.

Saccharin (Sweet’N Low)

With zero calories, saccharin is the oldest artificial sweetener, discovered in the 1870s. One of the most controversial chemical sweeteners, the Canadian government banned saccharin as a food additive in the 1970s, when laboratory rats were found to develop bladder cancer when fed large amounts of saccharin.

The US government also warned that it could cause cancer. However, following an evaluation in the 1990s, the International Agency for Research on Cancer concluded it could no longer be considered a possible carcinogen in people and Canada lifted its ban in 2014. However, it is not advised for use during pregnancy, as it has been shown to cross the placenta. Saccharin can be used for baking.


Sorbitol contains 2.6 calories per gram, and is produced in the same way as mannitol – to which it is very similar. Sorbitol can also be used for baking.

Sucralose (Splenda)

Zero calories and three times sweeter than aspartame, (600 times sweeter than sugar), sucralose has a long shelf-life and the ability to retain its sweetness after heating. Sucralose is replacing aspartame in many processed foods.

It is made by chlorinating sugar in a chemical process that also uses maltodextrin or dextrose (from GM-corn) as bulking agents. Although sucralose itself has no calories, the bulking agents that accompany it in packs add around 2-4 calories per gram (the FDA allows any product containing fewer than five calories per serving to be labelled as zero calories).

Reports of adverse side effects include claims it could trigger migraines, however, a review of evidence in 2000 found that it is safe for human consumption and does not affect blood sugar levels. Also listed as E955 on food labels, Sucralose can be used for baking.


With zero calories, this comes from the leaves of the Stevia bush, native to South America. In South America, it has been used it as a natural sweetener for hundreds of years and more recently in Japan since the 1970s.

Although it is a naturally derived plant, some argue that stevia is not a natural sweetener, as it has to be processed and refined to make it available commercially. However, it is perhaps the most natural of all the ‘synthesised’ sugar substitutes.

Those taking prescription medication such as lithium and diabetes drugs are advised to consult their doctor before using, although research shows that stevia may help lower both blood pressure and blood sugar levels. It is generally considered safe for use in pregnancy but little specific data exists on this, so perhaps avoid large amounts, along with all other artificial sweeteners.

Stevia can be used for baking. Limited data has linked large quantities fed to mice with microbiome disruption, not specifically replicated in the human digestive system.


Xylitol has 2.4 calories per gram, and was developed in 1963 as an artificial sweetener. Xylitol can be made from various foodstuffs, including berries, oats and mushrooms, but is invariably made from cheaper corn husks or xylan, a hardwood extract from trees.

Xylitol actually has some interesting health benefits, including being beneficial to teeth and has been shown to reduce the incidence of inner ear infection. However, it can also have a laxative effect and is highly toxic for dogs. Xylitol can be used for baking.

For more on artificial sweeteners and how to kick the sugar habit, read Liz Earle’s Quick Guide to Detox.