Artificial Sweeteners: What Do Studies Really Show? [2025 Review]

Chapters:

00:00 Intro

00:22 The new massive review of studies on sweeteners

01:10 Naive association studies and reverse causality

02:25 Animal research

03:04 My Online PT Course

03:24 Controlled trials

04:18 Aspartame

05:00 Conclusion

05:53 Outro

Transcript:

Artificial sweeteners are highly controversial. On the one hand, it seems like every week a new headline comes by that artificial sweetener usage is linked to cancer or problems with the gut microbiome. On the other hand, almost all official health organizations support the usage of artificial sweeteners. So what gives? If we look at the best available evidence, free from bias, what does the scientific research really show? On the surface it seems like many studies contradict each other. However, as is usually the case when studies seem to be contradictory, there is a lack of deeper understanding about how to properly interpret all the facts.

A new, massive umbrella review of other scientific reviews and meta analyses looked at all the evidence we have on the usage of low calorie sweeteners to assess if they are really okay or not okay for our health. Combined, these studies had 2.8 million participants in cohort studies and 25,000 studies in controlled trials. The review was conducted independently and none of the researchers had a financial conflict of interest. The studied sweeteners included aspartame, sucralose, stevia, acesulfame-K and saccharin. The review did not include sugar alcohols because those technically do have a non-trivial number of calories per gram. The researchers found that when we look at naive association studies, there was indeed a negative association between artificial sweetener usage and health outcomes. However, these studies simply observed, without any intervention or control, do people that use more sweeteners have more health problems?

In this cohort of individuals, there is a large problem with reverse causality. See, people that have more health problems, that are obese, or that need to use artificial sweeteners on doctor’s orders because they have diabetes, for example, they start using more artificial sweeteners because they have these health problems. So the usage of low calorie sweeteners is in these cases associated with health problems, but it’s due to reverse causality, not due to artificial sweeteners causing these problems.

The reason I can say that it’s confounders like reverse causality that the cause the problems is because when we look at controlled cohort studies which were bias adjusted, we no longer see these associations. So when we control for these confounders, we see that the associations disappear, and there’s no longer any relationship between the consumption of low calorie sweeteners and negative health outcomes. Problematically, it’s these naive association studies that got most of the publicity. Even the World Health Organization, when they recently issued a warning against the usage of low calorie sweeteners, relied on these naive association studies as evidence.

In the media you’ll also find many fear mongering headlines based on animal research. When it comes to low calorie sweeteners animal research is often literally designed to find health problems. They just keep increasing the dosage more and more until they find health problems, and then using certain formulas they convert that to a human equivalent dosage using a 100 fold error margin. So they come up with a dosage that is still okay in humans with a factor 100 error margin based on the lowest dosage that triggered health problems in certain animals. So the fact that animal research finds health problems where sweetener usage is literally by design. You would have to consume absolutely ludicrous amounts of sweeteners to get those health problems in a human.

When we look at the highest quality evidence, which comes from controlled trials in living humans, the researchers consistently observed no negative health effects of sweetener usage. In fact, when sweeteners were used as they should be – to replace sugar, they consistently led to positive health improvements. Not because sweeteners are healthy, but because sweeteners allow you to reduce your energy intake and when they displace other unhealthier foods in your diets, like sugar, this creates an energy deficit which can lead to fat loss, which has many positive health effects in most individuals.

Compared to water or neutral comparators, intervention studies consistently find no negative health effects and no benefits either. Basically, in terms of cardiometabolic health, whether you drink a Diet Coke or water doesn’t matter. However, multiple studies have found that using low calorie sweeteners like drinking Diet Coke can help with diet adherence by satisfying your sweet tooth. If drinking Diet Coke makes you not opt for dessert, then of course, these sweeteners are a net positive for your health. Speaking of diet sodas, most diet sodas use the sweetener aspartame.

Aspartame has a particularly bad reputation for being chemical junk. While it might sound scary to consume something artificial, aspartame is actually broken down into compounds that you also get in your food. So aspartame is not stored in a body, does not accumulate. It has broken down into harmless substances that are also produced where you consume food. Specifically, 50% of phenylalanine, 40% aspartic acid, and 10% methanol. All of these compounds are also found in your body when you consume things like milk, eggs, tomatoes, or meat.

The researchers concluded, based on their analysis of 101 scientific articles that: “Little to no effects of aspartame were found over the short term or long term, with no contraindications for health.” When it comes to your diet, it is generally a good rule of thumb to eat foods that were found in hunter-gatherer times and that are thus natural. However, just because something is not natural does not mean it is unhealthy. In the case of low calorie sweeteners, including artificial sweeteners, we have an abundance of research showing that they are safe for human consumption up to very unreasonable intakes. This is why multiple official health organizations allow these sweeteners to be used. They periodically review all the scientific evidence, especially after any negative finding comes out, and they have consistently concluded time and time again that sweeteners are okay for human consumption. If anything, they are probably a net positive because they help a lot of people stick to their diet, and it replaces things like sugar that are a lot more harmful.

If you don’t want to consume artificial sweeteners, that is of course fine. However, not consuming artificial sweeteners and then consuming sugar is a lot like not using a condom during a hookup because you’re worried about the latex or the plastic poisoning. If you like this type of no-nonsense, evidence based information about health or fitness, I’d be honored if you like and subscribe. And if you’re a serious lifter that wants to take their physique to the next level using evidence based fitness methods, check out my online course in the description.