How safe are artificial sweeteners?

In the first part of my update on artificial sweeteners, we considered which sweeteners are available in South Africa and the strict tests they are subjected to by international organisations such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA) (2012), before being approved for use by humans. Today, we will take a look at the public safety concerns that always emerge when we touch on this subject.

Scientific background

At a recent Oldways symposium on ‘Managing Sweetness’, Dr Bernadene Magnuson, Professor in the Department of Nutritional Sciences at the University of Toronto in Canada, when speaking about “Sweeteners and Sweetener Safety” addressed these consumer concerns and safety issues.


a) The Methanol Controversy

Most people who receive e-mails will have seen the "Aspartame e-mail" which links this non-nutritive sweetener to every ill known to mankind. Most people will have dismissed this as scare mongering, but there have been legitimate concerns that aspartame may have behavioural effects or be linked to nervous system damage. These concerns were based on the fact that aspartame contains 2 amino acids (phenylalanine and aspartyl) and a so-called methyl ester.

When aspartame is metabolised, the compound is broken down into phenylalanine, aspartate and methanol. Phenylalanine and aspartate are found in large quantities in all protein foods, so unless an individual suffers from phenylketonuria (a genetic disorder in which the body cannot process part of a protein called phenylalanine), no harm should be caused by these two common amino acids 

It is, however, the methanol which is formed from the methyl ester mentioned above, that has come under suspicion and had been held responsible for damage to the nervous system and aberrant behaviour.

Dr Magnuson (2012) pointed out that methanol is also formed in the human body from a variety of standard foods such as fruits and vegetables, something most people probably never take into consideration.

For example 1 medium banana produces 21 mg of methanol in the human body, while a 340 ml glass of orange juice is responsible for 23 mg of methanol, both of which compare well with the 18 mg of methanol which our bodies produce if we drink 340 ml of a cold drink that has been sweetened with aspartame.

The basic chemical evidence, therefore, does not support the theory that the methanol produced from aspartame will cause nervous system damage or change human behaviour.

But what do the studies show?

There are two types of studies that are used to determine if an artificial sweetener causes harm, namely consumption studies and animal and human clinical trials to determine negative side-effects.

1) Consumption studies

According to Dr Magnuson (2012), consumption studies have been conducted with aspartame in Australia, Brazil, Canada, Denmark, France, Germany, Italy, Korea, Netherlands, New Zealand, Portugal, Spain, Sweden, the UK and the USA, producing the following results:

  • Average users consume less than 1-10% of the ADI (ADI = Acceptable Daily Intake of 40 mg/kg/day as defined by the JECFA)
  • The highest users consume 45% of the ADI or 45/100 x 40 = 18 mg aspartame/kg/day
  • No report of anyone using or exceeding the aspartame ADI has been found worldwide.

2) Clinical trials

In addition, clinical trials have been carried out with many different animal species (using healthy animals or those that were genetically predisposed to developing a disease and even animals with induced disorders of the nervous system), which did not identify any aspartame-linked damage.

Dr Magnuson (2012) went on to report that when similar clinical aspartame trials were performed with normal children, hyperactive children, children with phenylketonuria, aggressive schoolboys, sugar-sensitive children, as well as healthy adults, aeroplane pilots, adults with Parkinson’s disease or those suffering from depression, no effect on learning, cognitive performance, behaviour, seizures or any other neurological parameters could be identified.

In similar fashion, the effect of aspartame on cancer has been disproved according to Magnuson (2012) and she concluded the section of her talk on aspartame as follows:

  • “there is no credible evidence that aspartame is carcinogenic”
  • “there is no need to revise the previously established ADI.”

But the regulatory bodies watching over our food safety never sleep, so they are reviewing all the data about aspartame again and will hopefully publish their findings by September 2012.

Not convinced?

For those members of the public who are not convinced about the safety of aspartame, there are of course a variety of other non-nutritive sweeteners which can be used instead.


A popular new edition to the sweetener arsenal, is stevia, which we also discussed in Artificial Sweeteners - part 1.

Stevia has been suspected of causing blood sugar variations, increasing blood pressure, and negatively affecting reproduction and kidney function. Based on scientific studies, it has become evident that crude or low-purity extracts of stevia (as are often sold illegally), may well cause some, or all of these negative effects (Magnuson, 20120).

On the other hand, studies conducted with high-purity extracts which contain 95% or more of steviol glycosides, have not shown any negative effects. This is then also the reason why the JECFA have specified that only stevia extracts that contain 97% pure steviol glycosides, can be approved for human consumption (Magnuson, 20120). It is thus important to be careful what type of  stevia products and/or food/drinks sweetened with stevia you buy. Purchasing products manufactured by reputable companies, should ensure stevia safety. 


It is good to hear that there are no legitimate safety controversies about the non-nutritive sweetener Neotame (a derivative of aspartame), which has also been extensively tested in mice, rats, rabbits, dogs and humans. Neotame has such intense sweetening properties (it is up to 13,000 times sweeter than sugar, and up to 60 times sweeter than aspartame), that it has the added advantage of only having to be used in extremely small quantities.

The week ahead

I have just realised that Easter and all those sweets and chocolates are around the corner. So I imagine that this information about artificial or non-nutritive sweeteners, will be a bit lost on most chocolate bunny and egg eating consumers. However, once you get over the Easter chocolate frenzy and are wonder about reducing your energy intake to compensate for this indulgence, then you will hopefully be able to make an informed choice when it comes to non-nutritive sweeteners.

- (Dr IV van Heerden, DietDoc, April 2012)        

(Photo of colourful candy from Shutterstock)                           


(JECFA (2012). Food Safety and Quality(JECFA).; Magnuson B (2012). Sweeteners and Sweetener Safety. Paper presented at Managing Sweetness, An Oldways Event in association with ADSA and SAAFoST, 23 February 2012. Sandton Convention Centre, Johannesburg.)

Any questions? Ask DietDoc

Read more:

Artificial sweeteners update
The sweet debate

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