Is Aspartame Carcinogenic? No

We tend to lean into all or nothing statements, they appeal to our sense of simplicity ; “Good things always happen to me”, “I am never lucky”, “drugs are bad”. But the word drugs for example includes, marijuana, methamphetamine, metformin, Tylenol and psilocybin, Each compound being completely different and having wildly different affects on our bodies. In this small list alone we have the potential to relieve pain, alter consciousness, save a life or take one . Is there any real meaning in the statement “drugs are bad”?

You might argue that we can understand context without explicitly mentioning it. But this is an assumption that goes against what we know about the strength of cognitive biases and black and white thinking patterns. Indeed because of this kind of thinking and slogan chanting we lost 70 years of research into the potential of psychedelics for the treatment of conditions such as PTSD, depression and addiction.

Another all or nothing phrase I have begun to see as problematic is “chemical free” or “chemicals are toxic”. I wrote about this about 12 years ago when I did a piece on aspartame. Unfortunately it has been lost to the data cloud gods and so I can’t quote it directly nor provide a link. But I began with a breakdown of the chemical composition of the baddie sweetener. Let’s start there. This is the chemical makeup –

N-l-α-aspartyl-l-phenylalanine methyl ester or 3-amino-N-(α-carboxyphenethyl)succinamic acid N-methyl ester

If your hackles are up already because of this long, hard to pronounce name take a breath and look at the chemical name of Vitamin C –

5R)-[(1S)-1,2-Dihydroxyethyl]-3,4-dihydroxyfuran-2(5H)-one

Or vitamin A –

(2E,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohex-1-en-1-yl)nona-2,4,6,8-tetraen-1-ol

Just because it has a complex name does not make it inherently toxic and everything is a chemical. The toxicity for aspartame, as for vitamin A (or any other compound you can ingest) depends on the dose. But let’s table that for now and look at the different parts of aspartame. Aspartame is made up of 2 amino acids; phenylalanine and aspartic acid, both of which occur naturally in our body and in food. A slight modification has been made to the phenylalanine by adding a methyl group. This is what gives aspartame its sweet flavour and is approximately 200x sweeter than sugar. Methyl groups are highly stable consisting of one carbon atom bonded to three hydrogen atoms (CH3). You usually see it as part of a larger molecule but can also be found alone in nature. It is indeed, natural.

When ingested, aspartame is broken down in the gut by enzymes. These enzymes break down the proteins into smaller molecules called peptides (phenylalanine and aspartic acid) which are then absorbed into the gut and used as building blocks to make protein somewhere else in the body or used for energy (this is really simplified but suffice for this conversation). So far so good, but what happens to the lab modified methyl group? This sweet sweet methyl group gets broken down into methanol. Methanol is made in the body when we eat certain foods, including fruits and vegetables but mainly citrus fruits. sounds innocuous, however we do know that methanol can be toxic at high levels such as from ingesting large quantities of home distilled alcohols. We also know that one of methanols oxidation products is formaldehyde, which is not something we think of as healthy . But before we can nix the sweetener due to its methanol content we need to go back to the earlier principle of the dose is the poison. What kind of exposure do we have when we ingest aspartame at normal levels and can our bodies remove the methanol byproducts or not?

Some of you who have a strong bias towards not adding chemical compounds to your diet are probably already leaning into your bias. Try and hold off. Remember that vitamin A is also a chemical, a set of molecules bonded together to form a larger molecule. We have use for some of its byproducts and we excrete what we don’t need. But if we ingest too much vitamin A, our filtering system becomes overloaded and we have abdominal pain, irritability, drowsiness and vomiting. The toxic overload consequences of some essential nutrients -nutrients we need to survive – includes death. Bare with me for a bit longer and let me woo you to the dark side…the sweetest side of all the sides…

We humans have an enzyme called alcohol dehydrogenase (ADH) that functions to break down ethanol into aldehyde, ketones and other alcohol metabolites. For Methanol, ADH first breaks it down into formaldehyde and then aldrohyde dehydrogenase breaks it down further into formic acid. Formic acid is benign in small quantities but can be toxic in large amounts and is part of the animal kingdom and plant world’s defences as is seen in bee venom, fire ant bites and stinging nettle. It has a low toxicity grade, meaning the quantity required to produce adverse affects is quite high, way above any quantities seen through food additives.

Formic acid is easily metabolized and excreted by the human body as long as we avoid concentrated doses. AT such high concentrations formic acid can cause damage to the optic nerve and blindness as is seen in methanol poisoning. There is some evidence that chronic occupational exposure to concentrated formic acid may result in kidney damage. This is not related to ingestion quantities but rather people who are exposed to this compound as part of an industrial solution. It has no bearing on health safety with sweeteners but I want to cover all bases so we have a deep understanding of the compounds we are dealing with. We should be able to fully accept that one compound can nutritious or benign and yet also toxic at high enough concentrations.

Let’s look at an example of human ingestion safety levels based off of a 3 month controlled/blind study on 43 individuals with type 2 diabetes. A person weighing approximately 200 lbs. is fed 1.8 grams of aspartame (this is the equivalent of 6.8 litres of diet soda) in one sitting. Blood levels show no remaining aspartame or metabolites but urine samples do show clear levels for up to 8 hours after ingestion. No evidence of toxicity found as all the metabolites were eliminated at the usual pace of liquid metabolization and nothing was found in the blood. No negative symptoms were reported by the participants.

In over 100 other studies performed after product approval, no negative symptoms have been shown any causal relation to aspartame use at the regulated dosage.

2 small case studies suggested a link between contact dermatitis and aspartame as well as migraines and aspartame. The theory for both is that a tiny percentage of the population may have a sensitivity to one of the metabolites. Possibly formaldehyde. But in no way is this a general conclusion as the vast majority of studies on the safety and metabolism of aspartame show no negative symptoms at and much beyond the regulated doses. Just like for vitamin A, C, K and many other essential nutrients, once you overload the elimination system, things get sticky. It is very important to understand this when making food choices.

Even phenylalanine can cause harm in people who are unable to digest it properly. We see developmental issues in the foetus of mothers who take in high doses of this amino acid if they can not process it. But this is a disease that approximately 450 000 people have worldwide. The same doses for the rest of the population have no effect on the mother nor the baby. Almost every food that you can think of that has protein in it contains this amino acid. So once again, it is both nutritious and possibly toxic. These are not mutually exclusive things, it depends on the dose and or sensitivity.

It makes sense to be asking yourself, why is this guy trying to convince me to drink Coke Zero? I’m not. When I work with clients with nutrition programs, I often have to begin with trade-offs. If someone is in a desperate situation and they need to lose weight quickly in order to stave off cardiovascular damage, metabolic issues, diabetes etc., then we may need to take the path of least resistance in order to make some quick progress. One of these paths has been to switch from regular soda to diet soda. Somewhere down the line, we work on weening off of all sodas or transitioning to plain soda water with lemon. The diet sodas may not be calorie dense or have the same effect on your blood glucose but they do stimulate your brain in similar ways to sugar and so the sugar cravings may continue. This is just a temporary trade-off for an important win in the weight loss category.

The other reason I am writing this is to continue in the vein of science literacy. Though I have not listed many studies in this post I am trying to give nuance to the conversation being had online right now about the burden of “toxic foods.” You may see such personalities as Casey Means, Mark Hyman, Rhonda Patrick, Joe Rogan or Ben Greenfield use words such as poison or toxin when speaking about foods or ingredients. And while some highly processed foods may contain ingredients that are not necessarily good for you, understanding that the dose is the poison can relieve the fear factor.

Recently I cam across a video published by Rhonda Patrick (whom I have much respect for and still follow closely) citing a huge list of “toxins” that are found in food or food containers. She offered some evidence for a few select compounds but mainly stuck with conclusions based on research that I saw no references for. A closer look at the reference of Aspartame as a possible carcinogen found it to basically be the opposite. The IARC has listed it as 2B – a possible carcinogen. The same category as Aloe. Because there are some animal studies that at very high doses have some inconclusive evidence of cancer causing mechanisms they need to make this classification. But they specify that this does NOT mean it is cancerous and are not concluding that it is. I understand the confusion but the deeper dive is necessary before alarming your audience. What does the person who has switched to diet sodas for the last 2 years to lose weight think after seeing her video? No one can get it right all the time. I sure as hell have not. But we can produce less content and be better at making our statements when we are unsure. Avoid sitting in any one “camp” when it comes to nutrition science or diet fads. Just take the information as it comes and adapt if need be. We don’t need to identify with how we eat.

Would it be better if these foods were not so widely available for cheap prices? It would be. But they are not going away any time soon so we need to clearly and calmly educate each other on how to navigate the food world. I feel zero guilt having a diet soda if for some weird reason I get a random craving a couple times a year. I would still have no guilt if it was every month because I feel safe in knowing that though I am not maximizing my nutrition intake, I am also not being pumped full of poison. I may change my mind if new evidence comes about. But so far aspartame is not the evil sweetener it has been made out to be. It is not cancerous at the tiny dose we get in foods, especially if our diet is mostly comprised of whole foods.

If you have comments or questions, please feel free to leave them here. Or if you would like to set up a consultation for a nutrition program contact me here. I have worked with people with all sorts of chronic illnesses as well as competitive athletes that need highly individualized programs. I bring nuance and science to each program. No fads, no non evidence based restrictions or supplements.