Aspartame linked with dementia and stroke – is it true?


Last week an article in the Daily Mail claimed that Aspartame (an artificial sweetener) in diet soda can triple a person’s risk of dementia and stroke. The article was published in response to recent US research. Prevalence of both these particular diseases are high throughout the UK with an estimated 850,000 individuals living with dementia, whilst stroke is the fourth largest single cause of mortality. So, what is the background behind this alarming article and do we need to avoid aspartame?


Artificial sweeteners are 0 kcal or low kcal chemical substances.  They are used in the place of sugar (sucrose) and naturally occurring sugars (syrups, honey, fruit juice and fruit juice concentrate) to add sweetness to a variety of products. Their negligible calorie content means that they are particularly useful for people wishing to control their kcal intake.

Aspartame tastes around 200 times sweeter than sugar and is widely used in food, drinks, medications, toothpaste and chewing gum. A number of internet hoaxes in the 90’s resulted in aspartame becoming vilified.  As a result, pseudoscience continues to make claims that aspartame causes a variety of conditions, including (but not exclusively): blindness; multiple sclerosis; cancer; diabetes; and, epilepsy.

Can we trust the research?

Researchers from the Boston University School of Medicine and Tufts University (Boston) wanted to investigate any link between artificially sweetened drinks and an increased risk of dementia and stroke.  They analysed data from the Framingham Heart Study (a cohort study) and several thousand participants were included.  At follow-up (10 years later) 3% of the cohort had suffered a stroke, whilst 5% had developed dementia.

The researchers adjusted the data to allow for confounding factors such as diabetes, high blood pressure and cardiovascular disease, which could negatively impact the results. No correlation was found between the use of artificially sweetened drinks and an increased risk of dementia. With regards to artificial sweetener and risk of stroke, once again no correlation was demonstrated with long term use.

The Daily Mail appears to have used data from a study where the necessary adjustments for confounding factors had not been made. This would have meant that the data was skewed giving inaccurate results. So, simply put, the evidence the mail cites isn’t there.

So, is Aspartame Safe?

Research by the European Food Safety Authority (EFSA) has led to them setting an ADI (average daily intake) of 40 mg per kg of body weight daily for aspartame.  Therefore, for a 70 kg adult this equates to 2800 mg per day. A typical can of diet cola contains approximately 180 mg of aspartame.  Therefore, an adult would need to drink approximately 5 litres (or 15 cans) per day over their lifetime before meeting EFSA’s ADI.

However, aspartame contains phenylalanine.  This can interact with medications such as MAOI antidepressants and Levodopa (used to alleviate symptoms of Parkinson’s Disease) and should be avoided. Additionally, phenylalanine should be avoided by individuals with Phenylketonuria (a rare, genetic disorder) and some mental health conditions. If you are unsure if aspartame or indeed any artificial sweetener is safe for you to consume, please consult a registered medical professional in the first instance.

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Any opinions above are the author’s alone and may not represent those of his/her affiliations. Any comment is based on the best available evidence at the time of writing.  All data is based on externally validated studies unless expressed otherwise. Novel data is representative of the sample surveyed. An online recommendation is no substitute for seeing your own doctor and should not be taken as medical advice.


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About Helena A L Fordham (5 Articles)
MMedSci student in Human Nutrition at the University of Sheffield. BSc (Hons) BA (Hons). Passionate about evidence based research.

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