The truth about artificial sweeteners

Artificial sweeteners are one of the most controversial topics of the fitness and wellness space. Some fitness gurus and bodybuilders idolize them, almost as if they were a miracle cure or short-cut to the „perfect body”. Others, including naturopaths and wellness influencers deem them to be harmful and should be always avoided. It is difficult to find a middle ground since both sides argue so vehemently whether they are safe to consume. But what is the truth about artificial sweeteners?

One of the biggest issues is that artificial sweeteners haven’t been around long enough to successfully study their long-term effects. New scientific findings resurface almost each day proving or disproving a fact about sweeteners that we had thought was true before.

Another problem when it comes to the public perception of sweeteners is the amount of misinformation out there regarding any wellness and health products. The fitness- and wellness industry is enormous and there are many businesses that take a huge interest in pushing for the safeness of artificial sweeteners. Just think about how many protein powders are flavored with sucralose or aspartame. On the other hand, if a company’s best-selling product is organic stevia extract, naturally they will be against other non-nutritive sweeteners, such as the ones mentioned before.

As a consumer, it is truly difficult to figure out who is telling the truth. Lucky for you, I’m here to help you understand both sides a little bit more.

Let’s start with the most basic question: what are artificial sweeteners?

Non-nutritive sweeteners (NNS) can be defined as “a group of chemical compounds that are characterized by high sweetening intensity and low energy value”[1]. They are in simple terms food additives which are considered safe for use in small doses by the European Union and the United States’ Food and Drug Administration.  The most widely approved NNS (derived synthetically) are aspartame, acesulfame-K, sucralose, cyclamate, neohesperidin DC, thaumatin, neotame, advantame, saccharin, and aspartame-acesulfame salt. Two NNS of natural origin that is widely used in the supplement industry are stevia and monk fruit extract/Luo Han Guo.

What got NNS popular are their ability to act as a sugar replacement and hence reducing overall energy intake and leading to better weight management. There are, however, growing concerns about the long-term possible negative effects of NNS and their linkage to non-communicable diseases (NDC-s) such as cancer, diabetes, and cardiovascular diseases.

 A common concern regarding NNS is that they increase the risk of cancer. In 2006 and 2007 a study conducted by the Ramazzini Institute revealed that aspartame causes increases in malignant tumors in multiple organs in rats and mice. Aspartame is a very common sweetener used in especially artificially sweetened beverages and has been very heavily scrutinized in recent studies and RCTs (randomized controlled trials).  A 2023 meta-analysis found only weak evidence regarding cancer mortality and cancer incidence. Furthermore, a systematic review by the WHO in 2022 found no significant association  between  higher  intakes  of  NSS-containing beverages and cancer mortality. However, even though the evidence is of low or very low certainty, all leading health experts agree that we cannot say with a 100% confidence that artificial sweeteners don’t lead to any undesired side effects later along the line. For this reason, most health experts caution against the excessive consumption of NNS until further research has been done on their long-term effects. In this article I bring you arguments for and against the use of artificial sweeteners as a diet tool and show you where the science currently stands and what the universal recommended guidelines are.

The effect of NNS on the gut-microbiome

The gastrointestinal tract takes part in breaking down most dietary components (macronutrients, fiber etc.) and helps the uptake of nutrients, ensuring that we meet our nutritional needs. The gut microbiome, on the other hand, is a community of microbes which has access to these dietary components during and after digestion and absorption and supports the fermentation of dietary components such as fiber. During this process, these microbes make it easier for the body to capture energy from dietary components which we would normally be unable to access and furthermore, enables the production of additional nutrients (e.g., vitamins), which then the human body can access. The study of the gut microbiome is relatively new thanks to recent analytical tools being available. As we learn more about the effect of the microbiome on development, nutrition and health, new correlations have been discovered regarding NNS and the gut microbiome.

Since NNS are among the most common food additives, it is important that we understand the potential effects of these compounds to change our gut microbiomes. In a recent meta-analysis on the relationship between the intake of NNS-containing foods and irritable bowel syndrome (IBS), scientists revealed inconsistencies in the findings of clinical test studies. However, there was one outcome that seemed consistent in the researched studies.  Namely, that has been a depletion of a certain microbe „Akkermansia muciniphilia” when exposed to NNS (saccharin, Acesulfame K, and sucralose) in mice studies. The review then compared this finding to the reported effects of NNS on human health parameters like glucose homeostasis (that relates to weakened glucose tolerance) and concluded that there might be a cause-and-effect relationship between the use of NNS-containing foods and direct and/or indirect influence on the gut microbiome, which then influences physiological responses such as glucose intolerance, increased body weight or metabolic modifications. The study further explained that the public including those with IBS (or other gastro-intestinal sensitivities) perceive artificially sweetened beverages and foods as part of a healthy diet and frequently consume them. In a controlled survey, participants with IBD were found to take a preference in consuming said products and although remaining within the recommended daily intake limits, consumption of these products were higher than other pills and powders. This was explained by the lack of awareness when consuming food or beverages as opposed to pills and powders. The main conclusions were drawn that there should be a higher level of awareness within the population to help consumers make conscious choices.

Artificial sweeteners and weight loss

One of the biggest, loudest claims of artificially flavored beverages and other food products is the presumed benefit of aiding weight loss. It just makes sense that if we’re replacing a can of regular soda with a can of diet (zero-calorie) soda we will consume about 160 calories less. This, in time, will lead to a caloric deficit and thus help us lose weight. However, there is some controversy since some studies have shown, on the contrary, that NNS consumption promotes weight gain over time. The 2022 WHO study concluded that use of NSS results in a small reduction in body weight and BMI in adults based on low certainty evidence. Furthermore, NSS had no significant beneficial effect on other health indicators such as adipose tissue and cardiometabolic health. During the tests it turned out that the effects of NNS on reduction of bodyweight were slightly more significant when participants were given NNS-sweetened beverages or sugar-sweetened beverages as an addition to their diet. This connection can be explained by the common knowledge that sugars play a huge role in unhealthy weight gain, especially when they are consumed as liquid calories. Naturally, those participants that were drinking sugar-sweetened beverages consumed more calories without compensating for them with a reduced overall energy intake. The reason for that is that in terms of satiety, the body doesn’t recognize calories from SSB in the same manner as solid foods.

These results all point to the outcome that in the short term, using artificially flavored drink in place of sugary beverages can lead to small reductions in weight and fat tissue without any significant impact on cardiometabolic risk. There is some data suggesting, however, that negative health effects might occur in the long-term, but the evidence is inconclusive.

One of the limitations of the research on NNS is reverse causation. The fact that individuals assessed as higher consumers of NSS tend to be already at a higher risk of disease because of excess body weight, high blood pressure etc. In some studies, participants that consumed the most NSS had higher body weight or BMI and had poorer overall diet quality. In another study carried out on children in the United States led to the conclusion that participants that consumed NNS also consumed other sugar containing foods, in common terms junk foods. This leads to the false causation that consumption of NSS lead to higher risks of non-communicable diseases.

Will the new WHO guidelines change the game?

In May 2023 the WHO issued new guidelines regarding the use of artificial sweeteners as a method to decrease bodyweight. In the new guidelines the WHO suggests that non-sugar sweeteners should not be used to achieve weight loss or reducing the risk of weight-related diseases such as hypertension or cardiometabolic diseases. The WHO based his recommendations on a 2022 meta-analysis and systemic review conducted by the organization that revealed a connection between the consumption of NNS and the risk of noncommunicable diseases (such as heart disease, cancer, chronic respiratory disease, and diabetes). Although the evidence is of low to very low certainty, the WHO advises against the use of NNS since according to the latest studies, there is no data supporting that using NNS will lead to fat loss in the long run, and together with the possible undesirable long-term effects, it is not proven to be a useful tool. 

However, the new guidelines underline the importance of maintaining a healthy body weight throughout the life course. It is strongly recommended to reduce the consumption of free sugars and sustain a healthy diet. Because free sugars are often found in highly processed, highly palatable foods and beverages, the new guidelines are in line with previous WHO recommendations of limiting the consumption of foods with low nutritive value. Simply switching the sugar with artificial sweeteners, will not make a significant impact of the quality of the overall diet. Ideally, free sugars should be replaced naturally occurring sweetness, such as fruits and other, minimally processed whole foods. And of course, to meet our daily water intake recommendations, we should prioritize unsweetened, unflavored water as opposed to flavored beverages.

Closing thoughts

Being a personal trainer and nutrition coach for years have taught me that you must meet people where they’re at. You just simply can’t change too many habits all at once, since that usually ends up in over restricting, scarcity mentality and then consequently binging. It doesn’t matter if we’re talking about the number of training sessions or the number of healthy meals. If I meet a new client and they never exercised a minute in their adult life, I cannot let them do 4-5 training sessions a week. They will end up overly exhausted (mentally and physically) and probability is high that they will give up exercise altogether within a month or two. To be able to organize their life in a way that would enable them to participate in so many sessions would involve changing around their routines and most probably lead to feeling deprived of other activities that they used to enjoy in their old life (such as watching tv or hanging out with their friends in the evenings). However, if they start incorporating 1 or 2 workouts per week, they might only need to change one variable. For example, on Mondays their partner will take their kids to school, and they have an hour to finish a workout in the neighborhood gym. They will stick to their new routine for weeks, then maybe after a month or two, after having gotten used to starting their day at the gym, they will voluntarily wake up an hour earlier on other days as well, just to make it to the gym before their family obligations. Changing our lifestyle takes time and cannot be rushed. The same goes with nutrition. If somebody is used to drinking soda instead of water, you can’t expect them to fully switch their sodas to unsweetened water without a problem. They will probably crave the sweetness and added flavors, which will make it very hard for them to stick to their new routine of only drinking plain water. Even if they are successful for a certain amount of time, for example completing a 30-day-challenge, they will most probably go back to drinking soda when their motivation is lacking. Let’s imagine this person becomes my client with a goal to lose their excess weight. I see from their food log that they’re consuming 400-500 calories worth of soda every day.  Instead of going cold-turkey, in this case, I would always recommend switching to a zero-calorie option as well as incorporating more and more plain water in their diet. Then they can focus on slowly changing their soda-drinking habits step-by-step. Another great example is high-calorie, high sugar Starbucks drinks. If a client starts each day with their Starbucks mocha-Frappuccino’s that pack around 400 calories and 50 grams of sugar (as opposed to the daily recommendation of 36 grams) I would not advise them to switch to black coffee, although theoretically that would be the logical choice.  My first recommendation would be instead to make themselves a coffee drink at home using a blender and sugar free coffee syrup and low-fat milk. This way they can mimic the flavor profile of the „real thing” thus satisfying their craving but saving them a few hundred calories each morning.

Obviously, a diet consisting only of artificially flavored, highly processed foods is just as unhealthy as the one high in free sugars, but in my opinion, non-nutritive sweeteners can be a smart addition in an otherwise calorie-restricted, whole-foods diet.

[1] Wilk, K.; Korytek, W.; Pelczyńska, M.; Moszak, M.; Bogdański, P. The Effect of Artificial Sweeteners Use on Sweet Taste Perception and Weight Loss Efficacy: A Review. Nutrients 2022, 14, 1261. https://doi.org/10.3390/nu14061261