Do Artificial Sweeteners Harm Your Good Gut Bacteria?

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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.
Your Gut Bacteria May Affect Your Health and Weight
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The bacteria in your gut play a major role in many of your body’s processes (1Trusted Source, 2Trusted Source).
Beneficial bacteria are known to protect your gut against infection, produce important vitamins and nutrients and even help regulate your immune system.
An imbalance of bacteria, in which your gut contains fewer healthy bacteria than normal, is called dysbiosis (3Trusted Source, 4Trusted Source).
Dysbiosis has been linked to a number of gut problems, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and celiac disease (5Trusted Source).
Recent studies have also suggested that dysbiosis may play a role in how much you weigh (6Trusted Source, 7Trusted Source).
Scientists examining gut bacteria have found that normal-weight people tend to have different patterns of bacteria in their guts than overweight people (4Trusted Source).
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 (8Trusted Source).
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 (6Trusted Source).
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 (4Trusted Source, 9Trusted Source).
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 (4Trusted Source).
SUMMARY:The balance of beneficial bacteria in your gut may play an important role in your health and weight.
Artificial Sweeteners May Change the Balance of Your Gut Bacteria
Most artificial sweeteners travel through your digestive system undigested and pass out of your body unchanged (10Trusted Source).
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 (11Trusted Source, 12Trusted Source, 13Trusted Source, 14Trusted Source).
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 (14Trusted Source).
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 (10Trusted Source, 15Trusted Source).
However, the effects of artificial sweeteners on gut bacteria may vary widely from person to person.
Initial human studies have indicated that only some people may experience changes to their gut bacteria and health when they consume these sweeteners (10Trusted Source, 16Trusted Source).
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.
They Have Been Linked to Obesity and Several Diseases
Artificial sweeteners are often recommended as a sugar substitute for people who are trying to lose weight (17Trusted Source).
However, questions have been raised about their effects on weight.
In particular, some people have noted a link between artificial sweetener consumption and an increased risk of obesity, as well as other conditions like stroke, dementia and type 2 diabetes (18Trusted Source, 19Trusted Source).
Obesity
Artificial sweeteners are often used by people who are trying to lose weight.
However, some people have suggested that artificial sweeteners may actually be linked to weight gain (20Trusted Source, 21Trusted Source).
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 (21Trusted Source, 22Trusted Source, 23Trusted Source, 24Trusted Source).
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 (25Trusted Source, 26Trusted Source).
However, a recent review couldn’t find any clear benefit of artificial sweeteners on weight, so more long-term studies are needed (23Trusted Source).
Type 2 Diabetes
Artificial sweeteners have no immediate measurable effects on blood sugar levels, so they’re considered a safe sugar alternative for those with diabetes (27Trusted Source).
However, concerns have been raised that artificial sweeteners could increase insulin resistance and glucose intolerance (19Trusted Source).
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 (14Trusted Source).
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.
Some observational studies in humans have found that frequent long-term consumption of artificial sweeteners is associated with an increased risk of type 2 diabetes (21Trusted Source, 28Trusted Source, 29Trusted Source).
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 (30Trusted Source).
Stroke
Artificial sweeteners have been linked to an increase in risk factors for heart disease, including stroke (21Trusted Source, 23Trusted Source, 31Trusted Source, 32Trusted Source).
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 (33Trusted Source).
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 (34Trusted Source).
Currently, there is little evidence to support a link between artificial sweeteners and the risk of stroke. More studies are required to clarify this.
Dementia
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 (34Trusted Source).
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 (35Trusted Source).
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.
Are Artificial Sweeteners Less Harmful Than Sugar?
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.
Eating too much added sugar has been associated with an increased risk of cavities, obesity, type 2 diabetes, poorer mental health and risk markers for heart disease (36Trusted Source, 37Trusted Source, 38Trusted Source, 39Trusted Source).
We also know that reducing your added sugar intake can have significant health benefits and reduce your risk of disease (40Trusted Source).
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.
However, there is some evidence linking a long-term high intake of artificial sweeteners to an increased risk of type 2 diabetes (21Trusted Source, 28Trusted Source, 29Trusted Source).
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.
Should You Eat Artificial Sweeteners?
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.