Aspartame – Sweet Poison or Harmless Sweetener?

Question of health safety of aspartame (E951) is one of the most controversial questions in the last 30 years when it comes to the human diet. It's mostly due to media sensationalism, which is the reason why many even today think aspartame is one of the greatest dietary poisons – despite countless research proving otherwise.

Aspartame is an artificial non-nutritive sweetener, used also as (mostly fruit) taste amplifier. Interestingly enough, it was discovered by accident. In 1965 chemist James Schlatter – neglecting the basic lab rules – licked his finger in order to lift the paper from the table. He had previously spilt the substance he was investigating. He noticed the sweet taste and this is where the aspartame story began – a white powder with no smell and with energy value the same as saccharose, the sugar we consume (4 kcal/g). However, it is 200 times sweeter than regular sugar so it takes a minimal quantity of aspartame to achieve the same level of sweetness. Aspartame is a methyl ester of the dipeptide with methanol as alcoholic component and aspartic acid and phenylalanine as peptide component. It is stable in dry conditions, but decomposes during prolonged thermal processing and loses some of its sweetness, so it is not suitable for foods that need to be thermally processed for longer periods of time. Due to aspartame being wide-spread, in over 6000 products, you must have consumed it, at least unknowingly. Non-alcoholic beverages, yoghurts, puddings, candy, and pharmaceuticals are just some of the examples.

In the digestive system, with the help of enzymes esterase and peptidase, aspartame is completely decomposed – hydrolyzed, to be precise – to abovementioned components methanol, phenylalanine, and aspartic acid. These are ingested in far greater quantities through regular diet. For example, a glass of milk has 6 times more phenylalanine and 13 times more aspartic acid, and a glass of apple juice has twice as much methanol than the same quantity of a beverage sweetened exclusively with aspartame. I emphasize the word exclusively because products are often sweetened using a combination of artificial sweeteners, especially in Europe.

An acceptable daily intake of aspartame (ADI) is 40 or 50 mg/kg body mass, depending on regulatory agencies for food safety (EFSA – European Food Safety Authority or FDA – Food and Drug Administration from the US). The average intake in Europe is around 3 and 10 mg/kg/day in population with a very high intake – e.g. diabetics – while in the US that number lies between 5 and 13 mg/kg. For example, to reach the still safe level of 50 mg/kg body mass, one should drink 6-7 liters of a beverage sweetened with aspartame only. It's good to know that ADI is calculated from NOAEL (no observed adverse effect level – the quantity which has been proven not to cause any side effects in lab animals) by reducing it 100 times. This leads to conclusion that an occasional higher intake is not dangerous for your health.

Even though research has followed the approval procedure more thoroughly than necessary, media, and especially the internet, are full of all kinds of stories and images about aspartame being exquisitely harmful. Interestingly, one of the main sources for this frenzy was a chain-email, still making rounds today, which was the exact reason I decided to take on the subject with a bit more interest. The reason for these headlines still being popular today is the fact they have just enough science behind them to seem factual to laymen. As a result of this global infatuation with aspartame's alleged harmfulness, it has become one of the most researched compounds in the world. We have countless scientific studies proving its safety over and over again, and only a few of those concluding differently – these are mostly done on animals, using quantities way over NOAEL. Only a few of serious studies showed aspartame can be harmful in quantities lower than ADI, but these were deemed absolutely worthless in scientific circles due to abundance of methodological errors.

After more than 30 years of scientific research, it can be safely claimed that aspartame is a safe dietary item which made quality of life a lot better for diabetics, allowing them to enjoy the taste of sweet without blood sugar fluctuations, and did the same for overweight people, with no unnecessary added energy value to foods consumed.

This article was published in the book called 100 (and a few more) tidbits on nutrition science, published by the Croatian Society of Food Technologists, Biotechnologists, and Nutritionists.

I participated in the 3rd International Student Congress „Nutrition and Clinical Diet Therapy“ (Rijeka, May 25-27, 2012) with the presentation called „Aspartame – sweet poison or harmless sweetener, where I won a prize for best oral presentation.


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