Can artificial sweeteners harm gut health and make you gain weight?

Can artificial sweeteners harm gut health and make you gain weight?

Early September we published an overview of various natural and artificial sweeteners that are currently available and possible avantages or disadvantages associated to them.
Until very recently the clear-cut explanation of all official governmental dietary agencies as well as most mainstream dieticians was that artificial sweeteners are harmless and not a single iota of proof was available to the contrary.

Even your humble writer still believed sweeteners are relatively harmless as by definition, rats and mice aren't human so evidence about harmfulness for those laboratory animals doesn't prove too much.
However, over time more and more evidence has come up that artificial sweeteners are truly not as good for your waistline as you think they are, in ways that wasn't looked at before. Our gut microbes, which have a bigger influence on your weight and insulin sensitivity than we realize, are negatively inflenced by the artificial sweeteners we ingest.

Gut bacteria may affect your health and weight

Beneficial bacteria are known to protect your gut against infection, produce important vitamins and nutrients and even help regulate your immune system.
When there's an imbalance of bacteria, in which your gut contains fewer healthy bacteria than normal, it is called dysbiosis.
Dysbiosis has been linked to a number of gut problems, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS) and celiac disease.
Recently a relation has been found between dysbiosis and being overweight as normal-weight people tend to have different patterns of bacteria in their guts than overweight people. Even for identical twins of which one is overweight and the other person has normal weight, the bacteria population in their gut is dfferent, which indicates this difference is not genetically determined.

Further evidence came from experiments in which scientists transferred bacteria from the gut of these identical human twins to mice, the mice that received bacteria from the overweight twins gained weight, despite eating the exact same diet.

To explain this phenomenon, you should know that while a particular food item can be assigned a specific amount of calories, macronutrients (carbs, fats, protein) and micronutrients (vitamins and minerals), this actual value for our body is a lot more fuzzy than we realize.
Not everything gets absorbed and metabolized by the body. How much of a food item is absorbed is largely dependent on the bacteria in our gut.

We learn from the study on mice how possibly the 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. The conclusion can be that a proper balance of beneficial bacteria in your gut can play an important role in your health and weight.

Artificial sweeteners can disrupt the balance of your gut bacteria

Most artificial sweeteners travel through your digestive system undigested and pass out of your body unchanged. 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.

Animals fed artificial sweeteners experience changes to their gut bacteria. The following sweeteners were tested : sucralose, acesulfame potassium, aspartame and saccharin.

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.
Interestingly, in the same experiment, these changes weren't seen in the mice fed sugar water.

In another, more recent study, two types of the commercially available stevia (proclaimed to be 'natural') was investigated.
More specifically, researchers looked at its influence on the growth of 6 different strains of Lactobacillus reuteri.
Both types of stevia impaired the growth of analysed strains, while the most pronounced effect was on lactic and acetic acid production.
We may conclude from this singular experiment how there is not so much difference in that aspect between so-called artificial and semi-natural sweeteners as stevia.

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.However, the effects of artificial sweeteners on gut bacteria may vary widely from person to person.
Some people appear to not be bothered at all, while others are more severely affected, so you could be the lucky person who can consume artificial sweeteners without any ill effect on your gut bacteria.

Sweeteners have been linked to obesity and other diseases

Artificial sweeteners are often recommended as a sugar substitute for people who are trying to lose weight.
However, over time, questions have been raised about how these sweeteners may affect our health.

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.


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 unexpected weight gain.
The reason why this may happen is because low-calorie sweeteners can disrupt our ability to predict the metabolic consequences of sweet taste, and thereby limit our ability to respond appropriately to sweet-tasting foods.

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.
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.

It stands to reason to conclude how ingesting low-calorie sweeteners don't actually make you put on weight by themselves, but result in keeping a preference for sweet tasting foods. This will make it harder to refuse high calorie sweet tasting foods.

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.
However, it may be that artificial sweeteners could increase insulin resistance and glucose intolerance.

A group of scientists discoverd how 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.
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.

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.

Other diseases

An observational study recently found that people who drank one artificially sweetened drink per day had up to three times the risk of stroke, as well as a slight increased risk of dementia compared to people who drank less than one drink per week.
However this link between stroke and dementia 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, which means there is still not enough evidence to draw conclusions.

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.
We also know that reducing your added sugar intake can have significant health benefits and reduce your risk of disease.
On the other hand, artificial sweeteners are still considered a safe option for most people.
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. .
If you are concerned, your healthiest option is to reduce your consumption of both sugar and artificial sweeteners.
Swapping added sugar for artificial sweeteners may help people who are trying to lose weight and improve their dental health.

Should I 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, while remembering stevia isn't as natural as it is often proclaimed to be.

If you are worried about the effects of sweeteners on beneficial bacteria and yeasts in the gut, you can always make them grow better by adding more fiber to your nutrition. 
Or add extra probiotics by consuming fermented foods like yoghurt, kefir, Sauerkraut or probiotic supplements. 

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