Aspartame dangers – another myth without scientific evidence

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Every day there’s some person on social media claiming that this or that are harmful to human health. MSG. High fructose corn syrup. Gluten. None of those additives should worry you. But what about aspartame dangers? Are those real? Let’s take a look.

All about aspartame

Aspartame (which goes by the brand name Nutrasweet, although generic aspartame is also available) is a popular artificial sweetener, approximately 200 times sweeter than common table sugar or sucrose. Aspartame is a dipeptide of the natural amino acids Laspartic acid and Lphenylalanine – these amino acids or peptides are consumed regularly since they are a part of nearly any animal or plant protein.

So, let’s be clear. All amino acids in all life on this planet are the same. Whether those amino acids come from aspartame or your steak is irrelevant to the body. There’s no magical difference between the steak’s aspartic acid and phenylalanine and Nutrasweet’s.

Time to get even more science in this article. When aspartame is ingested while drinking your Diet Coke, it is hydrolyzed (broken down by water molecules) into its constituent components: aspartate, phenylalanine and methanol, in an approximate 4:5:1 ratio. No aspartame has been found in the bloodstream, since it is so quickly hydrolyzed in the gut, and only the constituent components are absorbed by the digestive system. And there are probably no transport mechanisms that can transfer aspartame from the gut to the blood stream.

Again, let’s be clear. Aspartame itself doesn’t get into the blood, only the constituent amino acids.

Setting aside the absolute safety of the amino acids (the body self-regulates amino acid production and usage), the one concern could be the methanol formed during the hydrolysis reaction in the gut. Except for the fact that most fruit juices, and the human body itself, produces much more methanol than can be consumed in many cans of diet soda.

Here’s some math. A 12 US fluid ounce (355 ml) can of diet soda contains 180 milligrams (0.0063 oz) of aspartame, and for a 75 kg (165 lb) adult, it takes approximately 21 cans of diet soda daily to consume the 3,750 milligrams (0.132 oz) of aspartame that would surpass the FDA’s 50 milligrams per kilogram of body weight acceptable daily intake of aspartame from diet soda alone. Moreover, methanol is not stored in the body, it is metabolized and then excreted. The only way for methanol to have a toxic effect is to ingest an amount so large that it temporarily cannot be cleared from the bloodstream and causes harm.

There just is no plausible pathway that small amounts of simple amino acids, substances that are prevalent throughout all food sources, and a tiny amount of methanol, a substance also found widely in fruits and vegetables, and is manufactured by the body as a byproduct of numerous metabolic processes, could have any effect on anyone.


Aspartame dangers?

Aspartame must be avoided by people with an extremely rare genetic mutation, called phenylketonuria, which leads to an inability to properly metabolize phenylalanine. But those with this disease not only must avoid aspartame, but also any protein that contains that amino acid. These individuals have a very restricted diet that only allows them to consume certain proteins.

Despite this overall lack of plausibility, aspartame dangers have been subject to pseudoscientific attacks almost from the day it launched. Internet hoaxes, government investigations, and unscientific studies have continue to make it appear there might be an issue with aspartame.

That’s why we have real science. The Scientific Opinion on the re-evaluation of aspartame (E 951) as a food additive (pdf), published by the European Food Safety Authority (EFSA), came to the following scientific consensus:

  • The amount of aspartame that is absorbed into the bloodstream is nonexistent in numerous human and animal studies. This supports the understanding that aspartame is hydrolyzed into its simple, and widely consumed and common constituent amino acids in the digestive tract.
  • Scientists have found no acute toxic effects of aspartame.
  • The available data did not indicate that aspartame had any genotoxic effect.
  • There were no aspartame-related increases in neoplasms and tumors in carcinogenecity studies.
  • They did recognize some studies indicated that aspartame should not be consumed in large quantities by pregnant women, not necessarily because of the aspartame itself, but possibly because of gastrointestinal disturbances and quality of overall diet. They established that the potentially harmful dose of aspartame is 1000 mg/kg/day, a few hundred cans of diet soda per day.
  • They noted that there was no epidemiological evidence for potential associations between consumption of aspartame and cancers.
  • A large prospective cohort study in Denmark found no consistent association between the consumption of artificially sweetened beverages (but not with aspartame specifically) during pregnancy and the diagnosis of asthma or allergic rhinitis in children.
  • Data did not support genotoxicity of the methanol metabolite of aspartame.

Those are the major points. The panel examined almost every claim about aspartame in detail, and reviewed all the scientific evidence–they found nothing. Aspartame is safe. They did recommend consuming less than 40 mg/kg body weight/day (less than the FDA’s recommended 50 mg/kg/day), that’s still 17 cans of diet soda. There are probably other issues to discuss if you’re at that consumption level of soda.


More aspartame dangers – or not

You’ve probably heard that aspartame can lead to metabolic disorders like type 2 diabetes. Except a large meta-analysis, a type of study that’s considered to be at the pinnacle of the hierarchy of scientific research, clearly shows that there is no link between aspartame use and the signs for type 2 diabetes, like blood glucose levels.

Possibly you believe that artificial sweeteners are related to obesity. Again, the evidence is very weak.

Maybe you think that aspartame is correlated with cancers. Another meta-analysis shows that that’s not true.

Now there is some, not high quality, evidence that aspartame is related to migraines and headaches. But much of that is based on anecdotes and one-off case studies. Some researchers propose that it is a placebo effect rather than a physiological one. It is possible that some people are sensitive to higher levels of phenylalanine.

However, that would mean these people with this so-called sensitivity to phenylalanine would have to avoid all of these foods with high levels of the amino acid – soybeans, egg whites, shrimp, chicken breast, watercress, fish, nuts, crayfish, lobster, tuna, turkey, legumes, and lowfat cottage cheese. So if one is to claim that aspartame causes these headaches, it should also occur after a plate of shrimp cocktail and lobster.


Aspartame dangers – the summary

So the rumors and innuendo about aspartame dangers are swirling everywhere. But the real science says it’s safe, and it’s probably not related to any conditions that are claimed to be caused by aspartame.

People demonize food ingredients all the time these days. Even scientifically minded individuals sometimes buy into the dramatic claims of pseudoscience, without actually reviewing the evidence. Sure, aspartame does taste different than good old fashioned sugar, but that’s a personal preference and has little to do with the safety of the product.

Moreover, there’s a lack of critical thinking about the costs and benefits of an additive like aspartame. Maybe it does cause headaches in a small number of people (and the evidence for this is unconvincing at best). But for some people, say those who are diabetic or obese, the benefits far outweigh any potential risks of consuming it.

Aspartame dangers are vastly overstated, and may even be nonexistent. Just enjoy your Diet Coke, if that’s your libation of choice.


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The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!