Sweeteners - cancer, diabetes, obesity. Are sweeteners really so unhealthy?

Aktualisiert: 10. Mai 2020

Sweeteners come under a lot scrutiny in society and in the media especially. We are told that sweeteners, such as aspartame, are carcinogenic or promote type 2 diabetes, obesity and high blood pressure and cause many other diseases people do not want to develop. The other side of the story tells us that sweeteners are completely unproblematic. Most of the time, however, people are making claims without the science. Fortunately, there is relatively good information out there, and in this article we take a closer look at the research and get to the bottom of what sweeteners do to our bodies and how unhealthy they really are.

How do sweeteners work in our body?

Sweeteners, just like sugar, bind to the sweetness receptors on our tongues and give the brain the signal that something sweet and probably high in calories has passed our external barrier. However, in contrast to sugar, sweetener has no calories and cannot be metabolized by the body. Sweeteners also have a much higher degree of sweetness than sugar. In addition to sweeteners, there are sugar alcohols / sugar substitutes, which have 2.4 kilocalories per 1 gram of sugar substitute compared to sweeteners (1). Sugar alcohols are obtained from fruit and vegetables and are, according to current knowledge, harmless to the body. However, they are absorbed more slowly in the gastrointestinal tract, which can have a laxative effect in high quantities, as they bind water in the intestine and can thus liquefy the stool.

There are also many studies claiming that sweeteners are carcinogenic, lead to obesity and cause glucose intolerance.

To put it simply: when we consume carbohydrates and especially sugar, our blood glucose levels (blood sugar levels) rise. This causes insulin levels to increase in the blood to lower the glucose levels. This is normally not a problem. However, a permanently raised insulin level can become problematic as our body will start to become less sensitive to insulin. The body can develop glucose intolerance when this happens as if high amounts of sugar are taken continuously, the body will continue to desensitise to the amount of insulin produced and blood glucose levels will become dangerously high. (2). This phenomenon is called type 2 diabetes. The best way to combat type 2 diabetes is mainly through exercise and a strict diet limited in refined sugars and carbohydrates, allowing your body to rebuild its sensitivity to insulin. Medication may also need to be taken. Type 2 diabetes can also be caused by excessive regular alcohol consumption, as alcohol is converted to sugar in the body and is extremely insulinogenic (3).

The problem with nutritional studies is that they are ALWAYS first tested on animals, for example rats or flies. If certain patterns are found, it is often appropriate to consider a study with humans. However, humans have such diverse individual factors as sleeping behaviour, consumption of stimulants or their origins and associated genetic differences. Therefore, a review of a single nutritional characteristic in the large and variable world of humans, such as the consumption of sweeteners, cannot really be considered an accurate representation for everyone. Since rats are obviously not human, nutritional studies involving animals should ALWAYS be treated with caution. The opposite has not always been confirmed in the human world today.

The current science on the subject

The Contra - Sweetener Study Situation

Animal studies have shown that consumption of sucralose and acesulfame-K cause a change in the "good microbiota", resulting in glucose intolerance in mice (4)(5).

The term "microbiota" describes the bacteria in the gastrointestinal tract, i.e. the various bacterial cultures that live in the gastrointestinal tract and form a complex system. In a further study with humans, which was carried out by American scientists in 2017, 17 overweight test subjects were tested for their glucose intolerance (6). The participants were first given a glucose-water mixture, after which their blood sugar levels were measured. In a further procedure, the test subjects were first given a sweetener-water mixture and then a glucose-water mixture with accompanying blood sugar measurement.

The result: During the measurement with sweetener + glucose, a significant increase of the blood sugar level took place. This shows that sweetener does not leave our body completely without being involved in the metabolism.

Point of discussion: The study lasted only 5 hours, the number of participants is very small and the usual eating behaviour of the test subjects was not tracked. Although there is a correlation between sweetener and an increase in insulin levels, there is also a correlation between obesity and impaired glucose tolerance. Furthermore, a correlation is not a causality (cause), which means that correlations are not automatically a cause. This would require a larger study with non-obese people who are given a consistent diet plan with adjusted calorie and carbohydrate levels. This proves to be almost impossible, which is why there is no such study (as there is today). The study also suggests that people who are overweight and have glucose intolerance are more likely to use sweeteners, which can actually be observed in practice.

In a study with mice, researchers tested for 11 weeks how mice react to the addition of sucralose, aspartame and saccharin. The mice were given either a glucose-water mixture or a glucose-sweetener-water mixture (4).

The result: After 11 weeks the mice that consumed sweetener and sugar developed a higher glucose intolerance compared to the other mouse test group.

The discussion: In the following, the researchers examined the "good microbiota" of the mice and found out that the reason for the intolerance is related to the intestinal bacteria of the mice. Sweetener cannot be metabolized by the mouse, but the intestinal flora does react to the substance. Afterwards, the mice were given an antibiotic, which destroyed the intestinal flora of the mice and glucose intolerance disappeared. In addition, the mouse faeces of the glucose-intolerant mice were taken and transferred to sterile laboratory mice, which are bred in such a way that they have no intestinal flora at all and these laboratory mice also did not develop glucose intolerance.

The pro - sweetener study situation

The same researchers in the mouse study used this approach and conducted the same study in 7 humans. They were given the maximum recommended dose of saccharin for one week. The result was that 3 of the participants showed no particular reaction to the sweetener-glucose mixture. Four of the participants, however, showed a small deterioration in glucose tolerance.

In a current paper from 2019, all studies on sweeteners and changes in the intestinal flora or glucose tolerance in humans were summarized and re-evaluated. This led to the conclusion that the animal studies are not transferable to humans and that further studies with humans are missing to clarify this connection. The Federal Institute for Risk Assessment also gives the green light here as long as the ADI (Acceptable Daily Intake) is adhered to. The word ADI describes how high the maximum daily consumption of sweetener can be for a whole lifetime without experiencing any adverse effects (8).

"Sweetener" "ADI-Value in mg/kg Bodyweight" "Organisation" "Date"

"Sweetener" "ADI-Value in mg/kg Bodyweight" "Organisation" "Date"

For aspartame, the "ADI value" (acceptable daily intake) is 40 mg per kilo body weight per day. This means that a person weighing 60 kg would have to consume 12 doses of 330 ml of an aspartame-sweetened diet soda each day for the rest of his life to reach this value (9). This is obviously completely unrealistic to achieve.

One study showed that with the help of sweeteners, test subjects were able to stick to their diet better and lose more fat mass (7).

Cancer and aspartame

Even on rodents, there is a meta-analysis from 2013 that explores 10 studies on aspartame and cancer and comes to the clear conclusion that there is no causal link (10).

A 2019 cohort study of 470,000 people also analysed the association between cancer and aspartame and concluded that there is no increased risk of cancer in humans (11).

In a recent paper from 2019 it is reported once again that the effect of sweeteners on the human intestinal flora cannot be scientifically proven. Further results and assessments require further large-scale studies with humans! (12)

Summary - What should all these studies tell us now?

As you have probably noticed, it is not easy to answer the question: "Are sweeteners healthy or unhealthy?" with yes or no. The current state of research clearly indicates that sweeteners do not pass through the body completely apathetically, but a causal link between diseases such as type 2 diabetes, cancer, obesity and sweeteners can be ruled out at the moment. The reason for this is that the studies with animals are not transferable to humans, as confirmed by various federal offices and institutions. Human studies simply lack valid and reliable results with many test subjects. This proves to be very difficult because humans are very individual and complex beings. In contrast, the study situation for sugar is relatively clear and very negative.

In any case, both sugar and sweetener should be handled with care, as our taste buds can quickly get used to the sweet taste and at some point we can no longer perceive sweet-tasting fruit as really sweet (13).

Advantages of sweetener

Compared to sugar, sweetener has no calories and a very high degree of sweetness, which allows you to better regulate your calorie intake. Studies have shown that test subjects lost more fat mass and most likely achieved their goal by using sweetener. By taking sweetener, unlike sugar, there is no insulin reaction, according to current knowledge. Sugar is harmful to teeth and has been shown to promote tooth decay. Therefore, the WHO recommends not to exceed the daily intake of 25-50 grams ADI (14). Subjectively, this figure seems to be relatively low and is not adhered to by many people. Sweeteners and sugar substitutes are used in most chewing gums and dental care products for precisely this reason, as they do not have any negative effects on dental hygiene.

Conclusion and recommendations

According to current studies, sweeteners are safe for humans as long as the ADI value is adhered to. However, the ADI for common sweeteners such as aspartame, sucralose, saccharin and acesulfame K is so high that it is completely unrealistic that one would consume these amounts from diet products.

Of course, it cannot be completely ruled out that in future studies with more people, the opposite will be discovered. It is clear that cane sugar is more harmful to us and there is a significant link between obesity and type 2 diabetes. Of course, the most sensible thing would be to stick to water and unsweetened tea, but we are all just people who want to indulge in treats every now and then. This article is intended to help you decide whether the current state of science on this subject advises you to use sweeteners rather than sugar, or whether you do not want to consume sugar or sweeteners because you think the risk of possible consequences is too great.

You have to make the decision yourself. Personally, I see more advantages than disadvantages in sweetener, because I can better regulate my calorie intake. It has also been proven to have no negative effects on your teeth. Nevertheless, caution is advised when consuming all sweets, no matter how they are sweetened.

Only people with PKU should avoid sweeteners completely, as they cannot process the breakdown product phenylalanine.

Addendum: In nutritional psychology, there are still approaches that consider whether a stress reaction is released in the brain when one consumes sweetener. If you are interested in this topic, please let me know in the comments (under the blog or on Instagram) if you are interested in the topic "Diet and Stress Reactions", since I wrote my thesis on this topic.

References: (All URLs were opened on 18.04.2020)

(1) ELMADFA, Ibrahim (2009): Dietetics. 2nd edition. Stuttgart: Eugen Ulmer

(2) Unbedenklichkeit von Zuckeralkoholen: https://www.fdiworlddental.org/sites/default/files/media/documents/Sugar-substitutes-and-their-role-in-caries-prevention-2008.pdf

(3) Kummer, Jürgen: Summary table of many foods with glycemic index, nutritional values and intolerances: https://jumk.de/glyx/

(4)Suaz J et al. (2014): Artificial sweeteners induce glucose intolerance by altering the gut microbiota: https://www.diabetes.org.br/publico/images/pdf/artificial-sweeteners-induce-glucose-intolerance-by-altering-the-gut-microbiota.pdf

(5) Uebanso T et al. (2017): Effects of Low-Dose Non-Caloric Sweetener Consumption on Gut Microbiota in Mice :https://www.mdpi.com/2072-6643/9/6/560/htm

(6) Yanina M et al. (2013): Sucralose Affects Glycemic and Hormonal Responses to an Oral Glucose Load: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3747933/pdf/2530.pdf

(7) Johnston & Foreyt (2013): Robust scientific evidence demonstrates benefits of artificial sweeteners:https://www.cell.com/trends/endocrinology-metabolism/fulltext/S1043-2760(13)00169-0?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1043276013001690%3Fshowall%3Dtrue

(8) BfR (2014): Evaluation of sweeteners and sugar substitutes: https://mobil.bfr.bund.de/cm/343/bewertung_von_suessstoffen.pdf

(9 ) https://www.aspartam.at/nebenwirkungen

(10) Mallikarjun & Sieburth (2013): Aspartame and Risk of Cancer: A Meta-analytic Reviewhttps://www.tandfonline.com/doi/abs/10.1080/19338244.2013.828674

(11) Lim U et al. (2006): Consumption of Aspartame-Containing Beverages and Incidence of Hematopoietic and Brain Malignancies: https://cebp.aacrjournals.org/content/cebp/15/9/1654.full.pdf

(12) Haighton L et al. (2019): Evaluation of aspartame cancer epidemiology studies based on quality appraisal criteria


(13) WHO (2017): Incentives and disincentives for reducing sugar in manufactured foods An exploratory supply chain analysis: http://www.euro.who.int/__data/assets/pdf_file/0004/355972/Sugar-report_WHO_107773_updated-and-revised-Dec-2017.pdf?ua=1

(14) Bartolotto C (2015): Does Consuming Sugar and Artificial Sweeteners Change Taste Preferences?:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4500487/

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