Artificial sweeteners are synthetic sugar substitutes that are added to foods and drinks to make them taste sweet.
They provide that sweetness without any extra calories, making them an appealing choice for people who are trying to lose weight.
All sorts of everyday foods and products contain artificial sweeteners, including candy, soda, toothpaste and chewing gum.
However, in recent years artificial sweeteners have generated controversy. People are starting to question whether they are as safe and healthy as scientists first thought.
One of their potential problems is that they may disrupt the balance of beneficial bacteria in your gut.
This article takes a look at the current research and examines whether artificial sweeteners change your gut bacteria, as well as how these changes might impact your health.
Beneficial bacteria are known to protect your gut against infection, produce important vitamins and nutrients and even help regulate your immune system.
Dysbiosis has been linked to a number of gut problems, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and celiac disease (5).
Scientists examining gut bacteria have found that normal-weight people tend to have different patterns of bacteria in their guts than overweight people (4).
Twin studies comparing the gut bacteria of overweight and normal-weight identical twins have found the same phenomenon, indicating that these differences in bacteria are not genetic (8).
Moreover, when scientists transferred the bacteria from the guts of identical human twins to mice, the mice that received bacteria from the overweight twins gained weight, even though all the mice were fed the same diet (6).
This may be because the type of bacteria in the guts of overweight people are more efficient at extracting energy from the diet, so the people with these bacteria get more calories from a certain amount of food (4, 9).
Emerging research also suggests that your gut bacteria may be linked to a wide range of other health conditions, including arthritis, type 2 diabetes, heart disease and cancer (4).
Summary: The balance of beneficial bacteria in your gut may play an important role in your health and weight.
Most artificial sweeteners travel through your digestive system undigested and pass out of your body unchanged (10).
Because of this, scientists have long thought they have no effects on the body.
However, recent research has revealed that artificial sweeteners may influence your health by changing the balance of bacteria in your gut.
Scientists have found that animals fed artificial sweeteners experience changes to their gut bacteria. The researchers tested sweeteners including Splenda, acesulfame potassium, aspartame and saccharin (11, 12, 13, 14).
In one study, scientists found that when mice ate the sweetener saccharin, the numbers and types of bacteria in their guts changed, including a reduction in some beneficial bacteria (14).
Interestingly, in the same experiment, these changes weren't seen in the mice fed sugar water.
The researchers also noted that people who eat artificial sweeteners have different profiles of bacteria in their guts than those who don't. However, it's still not clear if or how artificial sweeteners might cause these changes (10, 15).
However, the effects of artificial sweeteners on gut bacteria may vary widely from person to person.
Summary: In mice, artificial sweeteners have been shown to change the balance of bacteria in the gut. However, more human studies are needed to determine their effects in people.
However, questions have been raised about their effects on weight.
Artificial sweeteners are often used by people who are trying to lose weight.
So far, human studies have found conflicting results. Some observational studies have linked eating artificial sweeteners to an increase in body mass index (BMI), while others have linked it to a modest decrease in BMI (21, 22, 23, 24).
Results from experimental studies have also been mixed. Overall, replacing high-calorie foods and sugar-sweetened beverages with ones containing artificial sweeteners seems to have a beneficial effect on BMI and weight (25, 26).
However, a recent review couldn't find any clear benefit of artificial sweeteners on weight, so more long-term studies are needed (23).
Type 2 Diabetes
A group of scientists found that glucose intolerance increased in mice fed an artificial sweetener. That is, the mice became less able to stabilize their blood sugar levels after eating sugar (14).
The same group of researchers also found that when germ-free mice were implanted with the bacteria of the glucose intolerant mice, they also became glucose intolerant.
However, currently the link between type 2 diabetes and artificial sweeteners is just an association. More studies are required to determine whether artificial sweeteners cause an increased risk (30).
A study recently found that people who drank one artificially sweetened drink per day had up to three times the risk of stroke, compared to people who drank less than one drink per week (33).
However, this study was observational, so it can't determine whether consuming artificial sweeteners actually caused the increased risk.
Additionally, when researchers looked at this link over the long term and took other factors related to the risk of stroke into account, they found that the link between artificial sweeteners and stroke wasn't significant (34).
Currently, there is little evidence to support a link between artificial sweeteners and the risk of stroke. More studies are required to clarify this.
There isn't a lot of research on whether there’s a link between artificial sweeteners and dementia.
However, the same observational study that recently linked artificial sweeteners to stroke also found an association with dementia (34).
As with stroke, this link was only seen before the numbers were fully adjusted to take into consideration other factors that can increase your risk of developing dementia, such as type 2 diabetes (35).
Additionally, there are no experimental studies that can demonstrate cause and effect, so more research is required to determine if these sweeteners can cause dementia.
Summary: Artificial sweeteners have been linked to a number of health conditions, including obesity, type 2 diabetes, stroke and dementia. However, the evidence is observational and doesn’t take other potential causes into account.
Despite the concerns about artificial sweeteners, it's worth noting that consuming too much added sugar is known to be harmful.
In fact, most government guidelines recommend limiting your added sugar intake due to the health risks associated with it.
On the other hand, artificial sweeteners are still considered a safe option for most people (41).
They may also help people who are trying to reduce their sugar intake and lose weight, at least in the short term.
If you are concerned, your healthiest option is to reduce your consumption of both sugar and artificial sweeteners.
Summary: Swapping added sugar for artificial sweeteners may help people who are trying to lose weight and improve their dental health.
The short-term use of artificial sweeteners hasn't been shown to be harmful.
They may help you reduce your calorie intake and protect your teeth, especially if you consume a lot of sugar.
However, evidence on their long-term safety is mixed, and they may disrupt the balance of your gut bacteria.
Overall, there are pros and cons to artificial sweeteners, and whether you should consume them comes down to individual choice.
If you already consume artificial sweeteners, feel fine and are happy with your diet, there is no concrete evidence that you should stop.
Nevertheless, if you have concerns about glucose intolerance or are worried about their long-term safety, you may want to cut sweeteners out of your diet or try switching to natural sweeteners.