Artificial Sweeteners: Good or Bad?

Artificial Sweeteners: Good or Bad?

Biscuit with artificial sweeteners topping and flour

Artificial sweeteners are increasingly common. They give you the flavor without the calories. But are they safe compared to natural soda, or water? We break down the research!

When were artificial sweeteners invented?

We will focus mostly on the artificial sweetener aspartame in this article, as it is the most commonly used. Aspartame was actually discovered by accident in 1965 by a researcher trying to find a cure for stomach ulcers. His name was James M. Schlatter. James had accidentally spilled some aspartame on his finger, so when he licked his finger to turn a page in a book, he sensed a sweet taste! After reviewing eleven studies on the substance, the FDA and European countries approved the use aspartame in food in the 1980s. With over 40 years on the market, aspartame is now one of the most studied sweeteners in the world.

How artificial sweeteners work and how they affect the body

When you consume aspartame, it is broken down to two amino acids (protein) and methanol. Methanol is where the fear aspartame comes from. But don’t forget that the dose makes the poison.

A can of diet soda contains less than 190 mg aspartame. Animals given aspartame corresponding to 1500 cans (4,000 mg/kg) of diet soda daily over their entire lives have not developed any disease. Meanwhile, EFSA and the FDA recommend a maximum of 15-20 cans (40-50 mg/kg) per day for humans, which is already way lower than what is given to animals in studies.

Furthermore, only about 10% of ingested aspartame becomes methanol. Methanol doesn’t accumulate in your body either, it is broken down and peed out. Therefore there is no need to worry about aspartame acting as a poison in your body.

Are artificial sweeteners bad for you?

Over past decades, media has spread fear behind artificial sweeteners, claiming that they cause damage by increasing body weight, food cravings, and causing addictions, sometimes comparing sweeteners with cocaine addiction. (5) These analyses are, however, based on cherry picked studies looking at rats receiving huge doses of artificial sweeteners (1000 times higher than human consumption) from birth. They also use test tube studies, brain scans looking at the reward system, and correlation studies (more on thi later). Just because an effect seen in a rat or in a test tube or flashes on an MRI are not the same as effects on weight or health.

Overall artificial sweeteners are beneficial for promoting health when used in moderation. Newer sweeteners aren’t as well studied as for example aspartame which is most proven to be safe. Every person’s body is different, and metabolic responses could differ between people (for example: people born with metabolic disease PKU should avoid aspartame). There is and will always be an “unknown” factor to everything, which is why constant research is needed to prevent negative consequences.

Why artificial sweeteners are good

To know what is actually true about aspartame, we need to look at experimental studies where on humans actually measuring weight (as opposed to simply looking at brain scans or test tube studies). (6) We also need to look at all available studies, using so-called systematic reviews, where scientists go through all studies they can find on a topic to draw conclusions (they also actually explain how the authors searched for the studies, allowing anyone to reproduce the search to know studies weren’t cherry picked).

In his systemic review, P.J. Rogers et al concluded that, when looking at all the evidence, there is no reason to doubt that artificial sweeteners could help people restrict how many calories they consume and thus lose weight (7). Replacing caloric sweeteners (i.e. sugar, honey, syrup etc.) with artificial sweeteners could be one method to help the growing prevalence of obesity and diabetes worldwide. Still, science is never 100%, and there is still the need for long term experimental studies to confirm results from short-studies and term or observational studies.

This will always be demanded when it comes to any scientific question, but at one point we have to say that the evidence seems certain enough to give a recommendation, and in this case it is: artificial sweeteners are a better alternative than sugar for preventing weight gain for metabolically healthy individuals.

Why artificial sweeteners are bad

As mentioned above, there is a metabolic disease called PKU where people aren’t able to handle the amino acid phenylalanine. These people should avoid all sources of phenylalanine, including many protein sources, but also aspartame.

Overconsumption of all soda is also a risk for tooth health, which is why water is a better choice. But this applies to both sugar and artificially sweetened soda.

Newer sweeteners like saccharin might affect the bacteria in your gut negatively, but it’s really too early to tell, and even if this is the case it doesn’t seem to matter for weight or diabetes as we already have studies measuring these outcomes.

There are observational, low-quality studies that indicate an increased risk for dementia and ischemic stroke. You can learn more about why you can’t draw any conclusions from these kind of studies here.

Artificial sweeteners vs sugar

Usually, people are faced with the choice of foods/drinks sweetened with refined sugars or aspartame-sweetened drinks. It is very possible that long term studies may one day show harmful effects of artificial sweeteners like aspartame. But make no mistake: the evidence for the dangers of refined sugars is undeniably stronger than the evidence for the harmful effects of aspartame. Eating refined sugar without counting calories makes it very easy to gain weight. This is because caloric density and low effects on hunger. Obesity is in turn linked to an array of other diseases, such as type 2 diabetes, heart diseases and certain cancers. It’s therefore a good idea to reduce refined sugar consumption, but you don’t have to eliminate sugar completely.

Artificial sweeteners vs water for hunger, and weight gain

Piernas et al. conducted an experimental study where participants were asked to replace sugary drinks with diet drinks (the artificial sweetener group) or water (the control group) (8). The artificial sweetener group developed better habits, consumed less alcohol, desserts and caloric sweeteners compared to the water group. Looking at calories consumed, both groups ended up eating less calories, and this finding was statistically significant, but there were too few participants in the study to say that one group was better than the other. After 6 months, The artificial sweetener group reduced caloric intake by 30% (from 2283 kcal to 1601 kcal). while the water group reduced intake by 26% (from 2056 kcal to 1517 kcal). It is important to keep in mind that participants were part of a weight loss study, meaning that other influences might have contributed to their reduction in caloric intake.

Apart from the above, another study looking at caloric sugar alcohols (sorbitol, mannitol, xylitol, erythritol etc.) found that they might reduce the risk of cancer, have prebiotic functions, favor absorption of B vitamins, reduce the rise of blood glucose and insulin levels and increase mineral bioavailability. We talk more about sugar alcohols in our book Diet Like a Doctor.

Artificial sweeteners and diabetes

Diabetes is a disease where the hormone insulin isn’t working properly. Insulin’s main job is to move sugar from the blood into your cells to keep them from starving. While diabetes most likely is cause by a combination of lack of exercise, high body fat, lack of muscle and genetics, diabetics are often recommended to avoid foods that make insulin spike up and down. High insulin spikes would make blood sugar drop, which might make controlling diabetes more difficult.

Claims that sweeteners cause a spike in insulin are mistaken! One study looked at blood insulin levels after consumption of aspartame vs glucose vs fructose vs water. It found that only glucose and fructose caused rises in insulin. (1)

So for a diabetic looking to keep their blood sugar stable, aspartame won’t make your blood sugar levels go crazy. Instead, abandoning sugar sweetened soda for aspartame sweetened soda is a great way to cut calories to make fat loss easier. Lowering body fat is one major step towards reversing type 2 diabetes, so if water is no option, go with aspartame!

Artificial sweeteners and cancer

The science shows no convincing data to support that artificially sweeteners, particularly aspartame which is most well studied, causes cancer.  (2, 3)

The studies that do indicate a risk are low-quality observational studies (cross-sectional, case control studies.). They find “links” between sweeteners and disease, but don’t let us know if sick people use more sweeteners or if the sweeteners make them sick. The best evidence is experimental trials and prospective observational studies where people drinking aspartame and followed over time, and these show no risks.

Artificial sweeteners and the gut microbiome

We’ve gotten a lot of questions on effects on the gut microbiome. A study in Nature found that gut bacteria and insulin response are affected in mice after getting artificial sweeteners, but mostly in response to saccharin, an uncommon sweetener. (4)

Similar effects were seen in four out of seven humans given saccharin, but a bigger population needs to be studied to make sure that this finding isn’t a fluke, and whether this effect on insulin is anything worth caring about is still uncertain. After all, sugar has a much clearer effect in both mice and humans.

Practical Advice: Which artificial sweeteners are safe?

We recommend choosing aspartame whenever the alternative is sugar, and consuming regular sugar in moderation (max 5-10% of calories). Here’s how you should prioritize:

  1. Water
  2. Aspartame
  3. Other artificial sweeteners and sugar alcohols
  4. Refined sugars

In terms of refined sugar consumption, try to stay below 50 g added sugar per day. For reference:

  • A can of soda has 11 g refined sugar.
  • A serving of flavored fruit yoghurt (around 150 g) has 14 grams of refined sugar.
  • A sugar cube has 4 grams of sugar
  • A serving of sweet chili sauce has around 15 grams of refined sugar.
  • A serving ketchup has round 10 grams of sugar
  • A standard chai latte has around 10 grams of sugar
  • A 130 gram café muffin has around 28 grams of sugar.

Don’t forget though, you can’t simply look at the sugar content of a food to decide if it’s healthy or not. Instead you need to consider how it affects your desire to eat, and other rewarding properties. To learn more about this, check out Diet Like a Doctor.

  1. Rodin J. Comparative effects of fructose, aspartame, glucose, and water preloads on calorie and macronutrient intake. Am J Clin Nutr. 1990 Mar;51(3):428-35.
  2. Systematic review and evaluation of aspartame carcinogenicity bioassays using quality criteria. doi: 10.1016/j.yrtph.2018.01.009
  3. Health outcomes of non-nutritive sweeteners: analysis of the research landscape doi: 10.1186/s12937-017-0278-x
  4. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. doi:10.1038/nature13793
  5. PMCID: PMC2892765
  6. 10.3945/ajcn.112.048405 DOI
  7. 10.1038/ijo.2015.177 DOI
  8. 10.3945/ajcn.112.048405 DOI
  9. 10.1161/STROKEAHA.116.016027 DOI

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