Evil Sweeteners and Diet Soda

Ah, sweeteners. Another spawn of the devil? Or something that is once again completely overblown and hyped up by the Dr. Google experts? 

I know another controversial topic, and hey, I want to provide you with the most fact- and evidence-based information possible. Plus, this will give you some great points for coworkers when you are gathered around the virtual or maybe soon-to-be real-life water cooler.

Sweeteners and diet soda are an interesting topic because there has been a lot of science that has shown pros and cons. Unfortunately, it’s dry, and you may need some higher level of education and training to decipher and understand the nuances of the literature. Most Dr. Google experts don’t have this training and instead work from a biased perspective of parroting and exaggerating the aspects of the evidence that support their beliefs, so they can sell you their vegan, venti, latte, acai fit tea recipe.

Fortunately, or perhaps, unfortunately (depending on how you feel about me), I do have training. I wouldn’t say I am a pro but maybe a semi-pro with an injury as I did spend the majority of a year and ~$25,000 learning how to interpret the literature and apply it to practice. Yay for higher education and crippling student debt…

For full transparency, I have done my best to mitigate my bias in writing this blog as I do consume at least 1 can of Coke Zero daily and will likely do so for the rest of my life. This is because Coca-Cola is the most amazing company ever! Here’s to hoping Coca-Cola starts sponsoring me to help pay off my student debt. 

Anywho, let’s talk about some science. As always, I like to provide you with a bit of background information! 

What are sweeteners?

Sweeteners are sugar substitutes and pretty much do as named: sweeten and substitute sugar – I know, I know groundbreaking. They can be used as 0 calorie substitutes as they are 100-500x sweeter than regular sugar. Therefore, you need a lot less of them to achieve a similar sweetness level of sugar.

Today, they are found in a ton of different products, from diet soda to toothpaste and gum. Some of them have been labelled as scarier than others simply because they have been studied more. Most of them have been approved by the FDA for use as food additives, including saccharin, aspartame, acesulfame potassium, sucralose, neotame, and advantame. 

Stevia is a bit different as it is composed of steviol glycosides which are derived from the leaves of the Stevia plant, found primarily in South America. The FDA has been a little more suspicious of this one and has recognized it as generally safe, but some crude extracts of Stevia leaves are not allowed to be used as food additives. Some may think it is more ‘natural,’ but the reality is it is still very refined and processed. To be quite honest, the aftertaste has ruined anything I have ever tried it in – think a combination of black licorice and lousy coffee. 

Side note: If you enjoy black licorice, I am sorry to you and for you – but I don’t think we can be friends anymore. 

So, we know what they do, but are sweeteners actually killing us?

Well, the ‘woke’ keyboard warriors would like you to believe that. Sweeteners have been claimed to cause cancer, heart disease, diabetes, obesity, altered glucose tolerance, and affect your gut health. While we are at it, we should say they caused COVID too.

Now there have been some observational studies and animal studies that have suggested the aforementioned issues were caused by sweeteners. However, there were some shortcomings found in that literature, specifically, the observational studies: studies where we look at a group of people from a database and watch them over a period of time then determine their sweetener intake and see if they are more likely to have something terrible happen compared to a group that did not consume sweetener.

Observational studies do their best to account for confounders or issues that may affect the end results. However, it is challenging to account for everything. Upon reanalysis by different authors, when other confounding variables were taken into account, such as obesity, the possible risk of sweeteners suddenly disappeared between the 2 groups.

As well, the individuals in these observational studies tend to be >40 years of age and have other comorbidities such as obesity, insulin resistance, previous heart disease, etc. A big question remains. Did these people actually consume sugar-based foods (which we know increase your risk of the above) up to a certain point in their lives and then switch to sweetener-based foods when they started gaining weight or were diagnosed with one of the previously mentioned conditions? If so, the damage is already done, then sweeteners get blamed!? I feel like sweeteners should be preparing lawsuits, and I will happily collect a percentage for bringing this information to light…

What about animal studies?! Well, mice are a little different than humans. “Obviously Dr. Dan, thanks for the fact of the day.” You are welcome. This is a crucial point to remember since the negative effects in the animal studies have not been replicated in human trials. Furthermore, it has been found that rats respond differently than humans to sweeteners. They can indeed cause cancer in rats; however, this is via a mechanism that humans do not possess.

Finally, on to the interventional trials. These are trials where we control all the variables and provide one group with the sweetener-based item. The other group gets a placebo. The only difference between the groups is the sweetener, which has not demonstrated negative effects as seen in observational and animal studies. There have even been some studies that have shown sweeteners might actually be beneficial for things like weight-loss.

These interventional trials tend to be our gold standard because of the control we have on them. Side note: Type A personalities thrive in creating an interventional trial environment because of all the control they have. However, I suppose most Type A’s perfection mindset and need to please may also lead them to biased study results, so they don’t let anyone down…

Anyways, the most recent interventional trial came out in 2021. It’s fresh off the press! It added more evidence that sweeteners, in particular saccharin, do not alter your gut microbiome or lead to issues with how your body processes glucose. Yay, science! It was a pretty well-done study as well.

Final Thoughts

We can’t ignore the observational or animal data. However, higher-quality studies and evidence show a different story and are likely closer to the truth, which is…..*drumroll please*… that sweeteners are safe, and they might even support your weight management efforts!

I am not saying you should start binging on diet pop. Diet pop also contains carbonic and phosphoric acid, which can cause other issues like melting your teeth away. Continue to be mindful! But, if you want to have a can of Coke Zero on the regular, there should be no issue. 



  1. Mendoza-Pérez, S. et al. Consumption of sweeteners at different stages of life: effects on body mass, food and drink intake in male and female Wistar rats. Int. J. Food Sci. Nutr. (2021) doi:10.1080/09637486.2021.1888077.
  2. Azad, M. B. et al. Nonnutritive sweeteners and cardiometabolic health: A systematic review and meta-analysis of randomized controlled trials and prospective cohort studies. CMAJ 189, E929–E939 (2017).
  3. O’Connor, D. et al. A rational review on the effects of sweeteners and sweetness enhancers on appetite, food reward and metabolic/adiposity outcomes in adults. Food and Function vol. 12 442–465 (2021).
  4. Spencer, M. et al. Artificial sweeteners: A systematic review and primer for gastroenterologists. Journal of Neurogastroenterology and Motility vol. 22 168–180 (2016).
  5. Brown, R. J., De Banate, M. A. & Rother, K. I. Artificial sweeteners: A systematic review of metabolic effects in youth. International Journal of Pediatric Obesity vol. 5 305–312 (2010).
  6. Romo-Romo, A. et al. Non-nutritive sweeteners: Evidence on their association with metabolic diseases and potential effects on glucose metabolism and appetite. Rev. Investig. Clin. 69, 129–138 (2017).
  7. Lohner, S., Kuellenberg de Gaudry, D., Toews, I., Ferenci, T. & Meerpohl, J. J. Non-nutritive sweeteners for diabetes mellitus. Cochrane Database of Systematic Reviews vol. 2020 (2020).
  8. Toews, I., Lohner, S., Küllenberg De Gaudry, D., Sommer, H. & Meerpohl, J. J. Association between intake of non-sugar sweeteners and health outcomes: Systematic review and meta-analyses of randomised and non-randomised controlled trials and observational studies. BMJ (Online) vol. 364 4718 (2019).
  9. Serrano, J. et al. High-dose saccharin supplementation does not induce gut microbiota changes or glucose intolerance in healthy humans and mice. Microbiome 9, 1–18 (2021).


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