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Is aspartame unhealthy? The artificial sweetener is often viewed with suspicion, but is that justified? In this article, we delve deeper into what aspartame is, how it is made, and how harmful it is.
The Fame of Aspartame
Aspartame. You don’t have to make an effort to find countless websites on Google warning you about its use. It’s said to be carcinogenic, cause headaches, trigger epileptic and migraine attacks, cause multiple sclerosis, lead to blindness, depression, fatigue, paralysis… the list seems endless.
But what’s true about all of that? Why could aspartame actually be harmful?
What is Aspartame?
Aspartame is an artificial sweetener that is about 200 times sweeter than table sugar (sucrose). So, you only need a tiny bit to sweeten something. It’s widely used in light products, such as soft drinks and dairy products. Because you need so little of it, it practically
provides no calories. That’s super handy if you want to lose weight.
All the sweet taste without the calories.
Chemically, it consists of two
amino acids (phenylalanine and aspartic acid) bonded together with a peptide bond, just like proteins. Proteins are a bunch of amino acids connected by peptide bonds. Because it consists of two amino acids bonded with a peptide bond, it’s also called a dipeptide.
How is Aspartame Made?
Aspartame is an artificial sweetener, so it’s produced through a series of chemical processes. As mentioned earlier, it consists of two amino acids bonded with a peptide bond. Additionally, there’s also a methyl ester on the phenylalanine residue.
First, the methyl ester is attached to the phenylalanine. By adding methanol to a solution with hydrogen chloride and phenylalanine, this linking (esterification) takes place. Then, a coupling reaction occurs to connect the two amino acids, followed by several steps to obtain pure aspartame.
How Harmful is Aspartame?
In addition to the name aspartame, the sweetener is also known by the E-number 951. Since it has an E-number, it means that the European Food Safety Authority (EFSA) has approved the substance for human consumption. A considerable amount of research is conducted before such a number is assigned.
In the case of aspartame, a tremendous amount of research has been conducted, much more than usual for E-numbers. Aspartame is one of the most researched substances in our food. If you search the biomedical database PubMed for clinical studies with ‘aspartame,’ you’ll find 144 publications. Other sweeteners such as ‘sucralose’ (51 publications), ‘cyclamate’ (18 publications), and ‘stevia’ (12 publications) yield far fewer results. The EFSA report contains 21 pages of scientific references.
Breakdown Products and Effects of Aspartame
When aspartame enters the gastrointestinal tract, it breaks down into, among other things, the two amino acids it consists of. However, these are present in much larger quantities in daily food intake. So, there’s no need to worry about that. An exception is made for phenylketonuria patients. These patients have a metabolic disorder in which the enzyme that normally breaks down phenylalanine is absent or does not function properly. This leads to an accumulation of phenylalanine in the body.
A third important breakdown product of aspartame is methanol. This is formed by the methyl group that is split from the dipeptide in the gastrointestinal tract. Due to the small amount present in products sweetened with it, you only ingest a tiny amount of methanol. Much less than with many other foods. For example, you get over ten times as much methanol from a liter of fruit juice as from a liter of aspartame-sweetened soda [1]. The amount of methanol produced is quite modest compared to other foods in the diet.
Another substance that can form is diketopiperazine (DKP). This occurs when the methyl group is released, leading to a rearrangement of the molecule itself. However, the amount formed is extremely small. Moreover, it falls well within the acceptable daily intake of this substance, as determined by various food safety agencies [2].
Eating Less or More with Aspartame?
In 1990, a study showed that knowing you have aspartame in your cornflakes instead of sugar, for example, makes you eat more [4]. “It’s light, so I can have more of it.” However, this is not caused by aspartame itself, as shown by a more recent study. It showed no greater intake when using aspartame if the participants didn’t know whether they were getting sugar or the substitute [5].
This study refutes the suspicion that aspartame itself would also make you eat more. Suspicions arose when it was found that aspartame stimulates the reward centers in the brain in the same way as sugar [6]. More dopamine is released, making you think, “This is good!” Other studies have also shown that aspartame inhibits the release of leptin [7].
Leptin is the hormone released when you eat and suppresses appetite. You have the taste in your mouth, and your brain says:
“Good!”, but you don’t get the calories, so you might eat more.
In the latter study, conducted on rats, it was found that replacing aspartame with
water resulted in lower weight.
Getting used to a certain taste makes you crave it [8]. So, replacing sugar with aspartame means you’ll still crave sweet things, especially if you eat more sweet things because you think it’s not unhealthy. But as mentioned, it’s not clear if this actually leads to eating more in practice.
Are there any studies showing weight loss with the use of aspartame? Yes, but in those cases, a diet and exercise regime likely contributed more to the weight loss [9,10].
Metabolic syndrome is a collective term for various symptoms of a metabolic disorder. In short, an imbalance between energy intake and expenditure. Typically, this is caused by excessive food intake and insufficient exercise. Aspartame is used as a sugar substitute to contribute to reducing energy intake. In this way, aspartame should theoretically reduce the risk of metabolic syndrome. However, this is not the case in practice.
Researchers at Massachusetts General Hospital recently discovered that aspartame may actually cause metabolic syndrome instead of limiting it [11]. Not because you eat more, but because of an effect of aspartame itself. It’s composed of two amino acids, aspartic acid, and phenylalanine. Upon ingestion, it breaks down into these two amino acids.
The research from Massachusetts General Hospital shows that phenylalanine (which also contributes to increasing dopamine) has an inhibitory effect on an important enzyme. This enzyme, called intestinal alkaline phosphatase (IAP), actually reduces the likelihood of metabolic syndrome and obesity, as previously shown in a study with mice fed this enzyme. Their study also showed that mice given aspartame gained more weight and exhibited other symptoms of metabolic syndrome.
We found that aspartame blocks a gut enzyme called intestinal alkaline phosphatase (IAP) that we previously showed can prevent obesity, diabetes and metabolic syndrome; so we think that aspartame might not work because, even as it is substituting for sugar, it blocks the beneficial aspects of IAP.
Massachusetts General Hospital
So, it’s a lot wiser to simply learn to eat less sweet than to replace sugar with aspartame.
Also read the article: Research: “Sweeteners Can Increase Risk of Metabolic Syndrome and Fat Absorption”
How Much Aspartame is Harmful?
The EFSA has kindly scoured the
entire literature and thoroughly assessed the safety of aspartame. In a report of 263 pages (!), the EFSA sets out everything and concludes that an intake of 40 mg per kilogram of body weight per day is a safe intake for people without the aforementioned metabolic disease [2]. You should understand that the EFSA is always
extremely conservative with their recommendations. In animal studies, no adverse effects are seen even with an intake of 4000 mg/kg body weight per day. So, with that 40 mg/kg body weight, you’re on the very safe side.
So, 40 mg/kg body weight, how does that compare to, for example, soda sweetened with aspartame? If you weigh 70 kg, you could ingest 2800 mg per day. The amount of aspartame in various diet sodas varies, but you’ll find a maximum of about 500 mg per liter [3].
In other words, a good 5 liters of diet soda a day. Which practically means as much as you want.
Conclusion
Aspartame is a sweetener that practically contains no calories. There has been a tremendous amount of research done on it, and all the research indicates that its consumption is safe up to a consumption of 40 mg/kg body weight per day. This means you can consume as much of it as you want. The fearmongering surrounding aspartame is absolutely
not based on sound scientific research.
So, enjoy it.
References
- Magnuson, B. A., et al. “Aspartame: a safety evaluation based on current use levels, regulations, and toxicological and epidemiological studies.” Critical reviews in toxicology 37.8 (2007): 629-727.
- EFSA ANS Panel (EFSA Panel on Food Additives and Nutrient Sources added to Food), 2013. Scientific Opinion on the re-evaluation of aspartame (E 951) as a food additive. EFSA Journal 2013;11(12):3496, 263 pp.
