Artificial Sweeteners- A Free Lunch, or an Obesogenic Carcinogen? What 80+ Studies Say. Part 2!
“Just a spoonful of sugar helps the medicine go down.”
NOTE - This article first appeared in Science Based Medicine.
Key Takeaways
It has been accused that artificial sweeteners cause weight gain and diabetes, disrupt gut bacteria, and even cause cancer.
Weight gain - Observational links between artificial sweetener intake and weight gain are highlighted in the media but can largely be explained by mistaking correlation for causation and the failure to recognize reverse causality. There are ZERO well controlled, experimental studies that show a causal link between artificial sweeteners and weight gain.
Diabetes - Consumption of artificially sweetened beverages are better for acute glycemic response and short-term metabolic health than fully sugar-sweetened beverages. There is no human evidence that shows artificial sweetener consumption increases one’s risk of developing metabolic syndrome or diabetes.
Gut Bacteria - Most of the information regarding the effect of AS consumption on the gut microbiota is speculation derived from observational research and studies performed on rats or in cell cultures. There is a significant need for more well-designed studies to assess this topic and, until that time, it is advised to proceed with caution - consume artificial sweeteners in moderation or not at all if you have concerns about the health of your gut microbiota.
Cancer - Counter to the findings of a study in the 80’s that linked aspartame with bladder cancer in mice, artificial sweeteners do NOT cause cancer.
Artificial sweeteners are not “healthy”, per se, and technically your diet may be better off without them. But for many, myself included, the pros of AS intake - increased adherence to macronutrient/calorie goals, increased enjoyment of food, and overall better physical and emotional health - outweigh the cons - potential increased appetite, decreased sensitivity to sweetness, and negative effects of very high doses on the gut microbiome resulting in decreased glucose tolerance.
Full Story
Last week, in Artificial Sweeteners- A Free Lunch or an Obeseogenic Carcinogen? What 80+ Studies Say Part 1, we explored the history of artificial sweeteners, had a mini lesson in research interpretation, and debunked the claim that artificial sweeteners cause weight gain, the most infamous accusation against synthetic sugar. This week, we take a look at the next three allegations, that artificial sweeteners:
Cause Diabetes
Disrupt Gut Bacteria
Cause Cancer
If we search PubMed, we’ll find studies that support these claims. But, we’ll also find studies that contradict them. This makes our job more fun, although significantly more difficult - instead of simply reading titles and abstracts, we have to assess the strength of the evidence to formulate an informed opinion. Lucky for you, I’m going to take care of all of it.
Additionally, we’ll discuss the ADI (acceptable daily intake) of the most common artificial sweeteners and my personal AS consumption habits. Sit back, relax, and let’s dive in.
2. Artificial Sweeteners Cause Diabetes
Now that we know that artificial sweeteners do not cause fat gain, it’s time to answer another question about its metabolic effects; do artificial sweeteners cause diabetes? Similar to the relationship between artificial sweeteners and obesity, researchers have found an observational link between AS intake and diabetes (1, 2, 3, 4).
Once again, these are observational studies and not well-controlled experimental trials- yet another example of correlation vs. causation and reverse causality leading to a misinterpretation of research. This being the case, the research only conveys that people with metabolic syndrome and diabetes are more likely to consume artificial sweeteners (probably in an effort to decrease sugar intake) and not that artificial sweeteners cause these diseases. In contrast, high quality studies have found that diet beverage consumption has no effect on metabolic disease risk (5, 6, 7).
To better understand the directionality of the link between AS intake and metabolic disease risk, let’s take a look at the studies on the impact artificial sweeteners on hormones and blood sugar response. A few studies have found that artificial sweeteners negatively impact satiety hormones and increase blood sugar levels. This mice study supports that artificial sweetener consumption may increase energy intake by suppressing GLP-1, a hormone that makes us feel full after a meal and plays an important role in glucose homeostasis (8). And this small study of seventeen obese women found that those that drank an artificially sweetened beverage before consuming a sugary drink had 14% higher blood sugar levels and 20% higher insulin levels, compared with those that drank water before the sugary drink (9). With this study in particular, as these women had not previously consumed artificially sweetened beverages, it is important to note artificial sweeteners may have different physiological effects depending on one’s age, genes, and history.
If I was trying to demonize artificial sweeteners – as many nutrition “experts” will do - I would end this section here and you would probably be convinced that your weight loss plateau is caused by the Splenda in your coffee. But, in the interest of painting a comprehensive picture, we must consider the opposing argument. In fact, the majority of human studies have found that artificial sweetener intake does not increase blood sugar, insulin levels, or other satiety hormones (10-21).
For instance, this randomized controlled trial of 50 people found that an intake of 2 diet sodas/day for twelve weeks had no effect on insulin response, as well as no effect on bodyweight or food intake (23). And in contrast to the previously mentioned rat study on GLP-1, this study found that artificial sweeteners had no effect on GLP-1 release in healthy human subjects (24).
In conclusion: There is no doubt that consumption of artificially sweetened beverages are better for acute glycemic response and short-term metabolic health than fully sugar-sweetened beverages, and there is no human evidence that shows artificial sweetener consumption increases one’s risk of developing metabolic syndrome or diabetes.
3. Artificial Sweeteners Disrupt Gut Bacteria
The study of the gut microbiota is a relatively new science with far-reaching implications. It appears likely that the types and number of bacteria that reside in the gut affect many facets of health, from body composition to mood to heart and brain health. For a great research-backed intro on the importance of gut health, check out this 2017 Healthline article (25).
While it is becoming increasingly apparent that the condition of our gut plays an integral part in the maintenance of our health and wellbeing, the impact of artificial sweetener intake on gut bacteria is not as clear-cut. First, we know that the food we consume does have an impact on the number, structure, and activity of the bacteria in our gut (26, 27). It follows, then, that artificial sweetener intake would have an effect on the gut microbiota. The question at hand is whether that effect is positive, negative, or inconsequential. Holding strong to the common theme with artificial sweeteners, it’s complicated.
In mice studies, the effect of artificial sweetener intake on the gut microbiota looks grim. In general, mice that are given artificial sweeteners experience negative changes to their microbiome, resulting in more fat gain and an impaired metabolic response to glucose, compared to their counterparts given water or sugar sweetened beverages. In some studies, it is suspected that the metabolically damaging effects are due to increased hunger and caloric intake, while in others it is speculated that the negative effects are caused directly by altered gut microbiota resulting in decreased glucose tolerance and insulin sensitivity (28-33).
Fascinatingly enough, some studies even found that artificial sweetener resulted in adverse metabolic effects despite positive changes in body composition. For instance, this 2014 study found that mice fed artificial sweeteners had increased fasting glucose levels and more insulin resistance than the mice fed sugar, despite having a lower bodyweight and improved body composition (34). For people that consider their physique a reliable indicator of health, this finding is especially concerning – this particular study indicates that artificial sweeteners may have an insignificant effect on our physical appearance but, nevertheless, may cause metabolic damage. As we know from “metabolically obese, normal weight people,” it is certainly possible to look “good” on the outside but be in poor physical health (35).
However, (shocking!) not all of the research is consistent. This study found that artificial sweetener intake actually improved glucose tolerance in insulin resistant mice and this study found that Stevia intake had no impact on bodyweight or glucose tolerance (36, 37).
Once again, let’s break down the two sides of the evidence. As we now know, there is a mountain of evidence showing that high intakes of artificial sweeteners in mice wreaks havoc on gut bacteria and results in serious adverse metabolic consequences. On the other hand, humans are not mice and most people do not consume even close to the amount of artificial sweeteners used in these studies. For instance, this rodent study found harmful effects on the gut microbiome, except it was with doses of artificial sweetener equivalent to humans eating 165 packets of Splenda or 36 cans of diet coke per day, for 6 months! (38).
If you know anyone that consumes 6,500 cans of diet soda in a 6 month time frame, he/she may have cause for concern. Otherwise, I am skeptical that AS intake in moderation, i.e. not 36 cans of diet soda a day, as a component of an otherwise well-balanced, primarily whole foods diet will have significant harmful effects on the gut microbiota (39).
In conclusion: The gut microbiota is a complex realm of human physiology. For this reason, it is the effect of artificial sweeteners on gut bacteria that gives me greatest pause with my personal AS consumption. Most of the information regarding the effect of AS consumption on the gut microbiota is speculation derived from observational research and studies performed on rats or in petri dishes. There is a significant need for more well-designed studies to assess this topic and, until that time, it is advised to proceed with caution. Consume artificial sweeteners in moderation or not at all if you have concerns about the health of your gut microbiota (40).
4. Artificial Sweeteners Cause Cancer
Do artificial sweeteners really cause cancer? Despite all of the evidence that supports the contrary, the scary myth that diet soda is a carcinogen still be heard today at water coolers around the world. After a study was published in 70’s that showed saccharin caused increased rates of bladder cancer in rats, it was claimed that artificial sweeteners caused cancer (41). As a result, in the 80’s the FDA required that artificial sweeteners come with a warning label and saccharin was even banned in the U.S. until 2000. In Canada, it was banned until just a few years ago! (42, 43).
Not so fast, Canada. The bad news - a lot of innocent rats were killed in that study. The good news - the dosage of artificial sweeteners given to the rats was outrageously high, rats are not humans (in case there’s still confusion), and the carcinogenic effects, as it turns out, do not translate to humans (44). This subsequent study found no association between saccharin intake and bladder cancer in humans (45). Future studies on sucralose and stevia have concluded that they are also not carcinogenic to humans (46, 47).
In conclusion: You can rest assured that artificial sweetener intake does NOT cause cancer. If I haven’t yet convinced you, here are some more resources that explain the history of the relationship between artificial sweeteners and cancer.
Artificial Sweetener ADI (Acceptable Daily Intake)
Acceptable daily intake is the maximum amount of a compound that can be consumed daily over a lifetime that is deemed to not cause appreciable adverse health effects (51). The ADI for the most common artificial sweeteners is very high. This is important to note because many of the studies I cited, especially those that showed harmful health effects, used doses of artificial sweeteners that were near or at the ADI.
Sweetener ADI
Aspartame 50 mg/kg/d (21 cans of diet soda)
Sucralose. 5 mg/kg/d (31 Splenda packets)
ACE-K 15 mg/kg/d (30 cans of diet soda)
Saccharin 5 mg/kg/d (10 Sweet n Low packets)
Stevia 40 mg/kg/d (40 Stevia packets)
(52).
Although I’m sure they exist in some dark corner of the universe, nobody I have ever met consumes 20+ cans of diet soda per day. It is not a stretch to believe that, while occasional AS intake may be more or less harmless, 20 cans of diet soda daily may have some negative health effects.
My Personal Artificial Sweetener Intake
I’m not sure if you care - I’m sure most don’t - but I figured I’d share my personal average AS intake for your entertainment. For reference, I am a 24 year old male with a healthy body composition and above average cardio-metabolic health markers. That being said, I am not sure how consistent intake of AS will affect my long term health - we will find out!
Average day
9am - ~1 tbsp of monk fruit sweetener or 1 serving sugar free pumpkin spice syrup (sweetened with ACE-K and sucralose) in my coffee
10am- .5 scoop of protein powder (sweetened with sucralose and ACE-K) in my protein oatmeal
1pm- .5 scoop of protein powder (sweetened with sucralose and ACE-K) in my protein oatmeal
4pm- (a few times of week) - a serving of “water enhancer” (sweetened with sucralose and ACE-K)
7pm- .5 scoop of protein powder (sweetened with stevia and monk fruit) in my protein pudding
2x throughout the day - 1 stick of “5 Gum” (sweetened with sorbitol, mannitol, aspartame, and ACE-K)
As you can see, I am not afraid of the potential downsides of artificial sweeteners and consume them quite liberally throughout the course of an average day. Until definitive research is published that suggests low to moderate intake of AS results in significant adverse health effects, I will continue my daily AS consumption. Personally, my decision comes down to a simple fact: in regard to artificial sweeteners, the pros outweigh the cons.
Wrap Up
Human nutrition is complex. Every food decision is influenced by, just to name a few, biological, psychological, physical, societal and economic cues. The specific choice to consume artificial sweeteners is made even more complicated by mixed research, conflicting expert opinions, headline-grabbing fear mongering, and logical fallacies. It’s not a black and white concept, and there is no correct answer that applies to everyone.
That being said, it is our responsibility to consider the strength of the available evidence and our individual circumstance to make the best possible decision for our health and wellbeing. After performing a thorough cost benefit analysis, I have made my decision.
For me, the pros of artificial sweeteners:
increased adherence to my macronutrient/calorie goals
increased enjoyment of my food
increased diet satisfaction while strictly limiting my intake of hyper palatable “junk foods” such as donuts, cookies, and ice cream,
outweigh the potential cons:
increased appetite
decreased sensitivity to sweetness
negative effects of very high doses on the gut microbiome resulting in decreased glucose tolerance
Sure, a diet sans artificial sweeteners may technically be “healthier”, but if their intake facilitates better overall health through lower caloric intake and decreased stress and feelings of restriction, it may very well be more optimal to include them your diet. Although at this point it does not appear that artificial sweeteners are a 100% risk-free biological free lunch, they are a useful tool that, when used in a reasonable way, can help us achieve our health and body composition goals.
Sources:
https://pubmed.ncbi.nlm.nih.gov/19808921/
https://pubmed.ncbi.nlm.nih.gov/29982723/
https://care.diabetesjournals.org/content/36/12/e202
https://www.healthline.com/nutrition/gut-microbiome-and-health
https://pubmed.ncbi.nlm.nih.gov/25231862/
https://pubmed.ncbi.nlm.nih.gov/25313461/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1564347/
https://pubmed.ncbi.nlm.nih.gov/32356872/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5522834/
http://www.sugar-and-sweetener-guide.com/acceptable-daily-intake.html
https://www.ncbi.nlm.nih.gov/books/NBK402050/
https://pubmed.ncbi.nlm.nih.gov/6103207/
https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/acceptable-daily-intake#:~:text=The%20acceptable%20daily%20intake%20(ADI)%20is%20defined%20as%20the%20maximum,rise%20to%20observable%20adverse%20effects.
https://www.fda.gov/food/food-additives-petitions/additional-information-about-high-intensity-sweeteners-permitted-use-food-united-states#SummaryTable
