Aspartame was always been a controversial food additive while I was growing up. There was rumors about it causing brain damage, and my father refused to let me drink any diet soda for fears of developing illnesses. As a child, I always wondered why we were allowed to consume such dangerous chemicals without regulations. Is it possible that aspartame’s ill effects are completely blown out of proportion?

Molecular structure of aspartame. Source: Wikipedia. License: Public Domain

Aspartame was approved for use as a table-top sweetener in 1981 by the Food and Drug Administration. In 1983, following its approval as a sweetener, aspartame found its way into carbonated beverages. The average intake of aspartame in the general public is around 4.9mg/kg.

The problem with aspartame

The use of aspartame has been a controversial one even to this day, with articles starting that the chemical causes illnesses such as headaches, seizures, weight gain, mood swings, nausea and many other health problems. It is believed that aspartame’s by-products from its breakdown are to blame because it produces methanol, aspartic acid and phenylalanine. Methanol is known as a poison and because it was believed that methanol is bound weakly to phenylalanine, it becomes free, unbound methanol within the body. In fact, aspartame is thought to be the largest source of methanol intake in an American diet. The other by-product, phenylalanine, is believed to accumulate in the brain and cause memory loss. Aspartame is so problematic that in 1995, a list of reported symptoms was sent to the Food and Drug Administration in order to get it banned for use. To this day, people are still reporting adverse results from aspartame such as nerve damage.

Scientific tests on the safety of aspartame use

With such horrifying results from aspartame intake, why is it that we are still using this poison in our foods in 2018? Perhaps aspartame isn’t as bad as the public think it is. Let’s begin with the by-products from metabolism that was said to be poisonous. Phenylalanine is one of the three observed components of aspartame breakdown.  Phenylalanine is believed to be able to affect serotonin release in the brain, but other adverse effects were not observed since it is metabolized in the same matter as other sources of phenylalanine. Methanol, although poisonous, is often consumed in many other forms of food such as fruits. Unlike previous claims that diet soda was the biggest contributor in methanol intake, Magnuson’s literature review claims that juice (especially tomato juice) has a higher methanol content than carbonated drinks. In addition, methanol is metabolized into formaldehyde which is then further metabolized into simpler components. Therefore, the methanol released into the body via aspartame is harmless with moderate intake of carbonated drinks. Lastly aspartic acid, a non-essential amino acid, is also found in aspartame breakdown. However, when high amounts of aspartic acid were given to non-human primates, no damage was observed.


Carbonated soft drink with aspartame. Source: Wikipedia. License: Public Domain

One of the biggest concerns from aspartame intake is its carcinogenic effect, where it can lead to the development of brain tumors. However, this does not seem to be the case with many studies suggesting that there is no link between aspartame intake and cancer development. Weihrauch & Diehl’s literature study suggests that animal studies do not show any cancer-inducing effects from high amounts of aspartame intake. In addition, children who are exposed to maternal consumption of aspartame did not show an elevated risk of brain tumor development. In fact, there was no carcinogenic effect found with aspartame nor any of its breakdown products with many studies finding that aspartame consumption up to 40mg/kg (way below the average intake of 4.9mg/kg) was entirely safe.

If aspartame does not have any carcinogenic effects, maybe it has immediate adverse effects? I distinctly remember that seizures were a big concern with aspartame consumption. Maher & Wurtman’s study suggests that aspartame does not induce seizures, but may promote seizure occurrences in animals that are already at risk. Thus, it may be possible that consuming too much aspartame, leads to increased phenylalanine in the brain which may increase seizure frequency. However, Butchko’s safety review argues that although it’s possible that seizure frequency may increase with phenylalanine intake, higher than average aspartame consumption shows that it still results in a safe plasma phenylalanine concentration. In addition, Butchko claim that even in doses 1000 times higher than the average aspartame intake in humans, it does not show any effect on brain chemistry and function.

Where does this lead us?

In conclusion, studies have shown no link between aspartame and carcinogenic effects, adverse physiological effects or adverse mood effects. In fact, aspartame may come with some benefits. Blackburn has shown that aspartame may facilitate weight gain because it helps control appetite. If there was no link at all between most of the claimed adverse side effects, then why does this negative stigma still exist to this day? Aspartame has been in use since 1981 and thoroughly investigated by many food safety administrations such as the Food and Drug Administration and the Joint Expert Committee on Food Additives. This negative stigma was powerful enough to affect my parents and relatives into distrusting diet soda. Perhaps the problem lies with the fact that scientists aren’t able to get their findings publicized or that media tends to sensationalize fear. Surprisingly, my initial mindset researching aspartame was to understand it’s adverse effects but I was blown away by the lack of evidence and general scientific consensus that aspartame is entirely safe for consumption. I guess the take home message is that you really shouldn’t believe everything you hear.