Are alternative sweeteners good for the gut?

Doughnuts and sugar in purple background

As people look to reduce their sugar intake, many turn to artificial sweeteners to provide that deliciously sweet flavour without the calories or blood sugar spike. But how do these sweeteners impact our gut health and what are the best options? 

What are alternative sweeteners?

Alternative sweeteners are used by the food industry as they are hundreds or thousands of times sweeter than regular table sugar. This means a small amount can be used to sweeten a product for very few calories. You have likely consumed these sweeteners in the form of diet soft drinks, sugar free confectionary, chewing gum or even pharmaceutical products. These sweeteners are classified as food additives and have been determined safe for consumption by Food Standards Australia and New Zealand. 

Non-nutritive sweeteners and gut health

Alternative sweeteners largely fall into two categories:

1. Non-nutritive sweeteners
2. Polyols 

Non-nutritive sweeteners can be chemically derived, such as aspartame, or naturally derived, such as stevia. They are considered ‘non-nutritive’ as they do not provide nutrition in the form of calories, vitamins, or minerals. Many non-nutritive sweeteners cannot be metabolised by our body so they travel through our digestive tract and interact with our gut microbiome. 

Our gut microbiome consists of trillions of bacteria which influence our metabolism, digestion, immune response, and overall health. The composition and function of our gut microbiome is influenced by the food we consume.

Research into the impact of chemically derived sweeteners and their impact on our gut microbiome have produced mixed results. A study by Suez et al. in 2014 found that high intakes of chemically derived non-nutritive sweeteners alter the composition of the gut microbiome in mice and humans. The good bacteria were reduced, and the bad bacteria increased – this is called dysbiosis. The study also found that this dysbiosis resulted in an increase in glucose intolerance. Glucose intolerance can lead to metabolic disorders such as diabetes. Not great news.

However, other studies found no impact on the gut microbiome or glucose tolerance when participants consumed these non-nutritive sweeteners. The evidence is mixed and we still require more information before we can clearly determine whether a high intake of non-nutritive sweeteners will negatively impact our gut microbiome and overall health.

On the other hand, naturally derived sweeteners, such as stevia, have had more positive results. A 2022 review found that stevia potentially has a positive effect on our gut microbiome. But, we still require more research and human studies to fully understand the impact of stevia on our gut health. 

In the meantime, if you are concerned about your gut health it may be best to limit your consumption of chemically derived non-nutritional sweeteners in ‘diet’ or ‘sugar-free’ products and choose stevia or full sugar options instead.

Polyols and gut health

Bunch of red grapes

Polyols or sugar alcohols naturally occur in certain fruits and vegetables but can also be chemically derived and used as a food additive. They are called sugar alcohols due to their chemical structure but do not actually contain alcohol. Some common polyols include mannitol, sorbitol, and erythritol. If you have completed a low FODMAP diet for IBS you are likely familiar with them. Polyols are less sweet than non-nutritive sweeteners so are used in larger quantities. Due to being poorly absorbed by our digestive system, they still provide fewer calories than white sugar. This poor absorption also means they travel undigested through our intestine and are fermented by our gut microbiome.

Excessive intake of polyols can lead to gastrointestinal discomfort, flatulence, and a laxative effect in all people. This is because polyols have an osmotic effect meaning they draw water into the bowel as they travel along the intestine. Their fermentation in the large bowel also produces gas which can cause discomfort and bloating, particularly for people with IBS. That is why packaged foods containing polyols will often have the warning “excessive intake can cause a laxative effect”.

Polyols have a more favourable impact on the gut microbiome. Certain polyols such as isomalt and maltitol have a prebiotic effect and can increase the number of good bacteria in our gut. While polyols may be the preferred sweetener it is important to recognise their gastrointestinal side effects. It is still best to consume polyols in the form of fruits and vegetables such as apples, pears, berries, stone fruit, and mushrooms.

Final verdict

More evidence is needed before making a definitive statement on the impact of alternative sweeteners and gut health. Current research suggests limiting our intake of non-nutritive sweeteners. Instead choose normal sugar options or sweeteners like cane sugar, maple syrup and honey. If you would like to include low-calorie sweeteners, stevia may be the better option. Polyols can also be a good alternative sweetener but be cautious with your intake due to their gastrointestinal side effects.

This blog post also appears in Nutrition in Mind. 

References

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