Microbiota and Sweeteners
We’ve been hearing more and more about microbiota these days. A number of scientific studies have recently sought to assess the microbiota’s characteristics, its benefits to health, and its interactions with food. One example is consumption of dietary fibre. Scientific studies have found that the gut microbiota metabolizes fibres to produce new bioactive compounds, short-chain fatty acids, which have an impact on the host’s metabolism and immunity. These compounds help to explain, among other things, the observed advantages of fibre on health, such as improved satiety and digestive health and reduced inflammation.
Sweeteners are present in a number of commercial products, such as sugary drinks, desserts, candies, chewing gum and jams. Despite their sweetening power, they contain little or no calories, which positions them as a valuable alternative to “traditional sugars” by reducing energy inputs, added sugars, and keeping the effects on glycemia (blood sugar level) to a minimum.
The most commonly used sweeteners are:
- steviol glycosides
- sugar alcohols, or polyols (including mannitol, sorbitol and xylitol)
Various health organizations have stated that their consumption is safe as long as maximum daily quantities are not exceeded.
Certain types of sweeteners are naturally present in foods and can cause intestinal discomfort in people with irritable bowel syndrome (IBS). Mannitol and sorbitol, for instance, have prebiotic properties and laxative effects. These two types of sugar are also found in low-FODMAP foods, which have become widely popular in recent years among those with gastrointestinal disorders for their ability to alleviate food intolerances.
However, sweeteners continue to attract controversy, including questions over their effect on the gut microbiota. Here is a rundown of the studies on the effects of some of these sweeteners on intestinal bacteria:
- Consumption of acesulfame-K has increased Firmicutes bacteria and reduced Akkermansia muciniphila in mice. A study in humans did not find any effect, while other studies showed changes in the microbiota and short-chain fatty acids, such as butyrate and pyruvate.
- Consumption of aspartame has demonstrated alterations in rodent microbiota by reducing the abundance of Enterococcaceae, Enterococcus and Parasutterella and increasing the abundance of Clostridium cluster IV. A study in rats also found alterations in the intestinal microbiota and in fasting glycemia after eight weeks’ use of aspartame. A study in humans showed that the administration of aspartame with maltodextrin increased the growth of Bifidobacterium and Blautia coccoides and reduced the Prevotella-to-Bacteroides ratio.
- For sucralose, a study in men found no change in the microbiota. Another study found an increase in the abundance of the pro-inflammatory bacteria Turicibacter after the administration of sucralose. A second study in 13 participants found an increase in the abundance of Escherichia, Shigella and Bilophila with sucralose. Certain studies in mice have found changes in the microbiota, such as a reduction in Bacteroides and an increase in Clostridium cluster XIVa.
- The administration of saccharine increased the abundance of the bacteria Bacteroidetes, Turicibacter and Clostridiales and reduced the abundance of Firmicutes and Akkermansia muciniphila, observed in animals and in vitro.
In humans, a study of 381 non-diabetic subjects found correlations between the consumption of sweeteners and metabolic syndrome markers. Consumption of sweeteners was positively correlated with higher levels of glycosylated hemoglobin (average glycemia in the last three months). Authors have suggested that the microbiota may be involved in the modulation of taste preferences and the consumption of sweeteners by manipulating taste receptor expression.
Given the lack of scientific studies in humans, a consensus of experts has concluded that current data are limited and do not provide sufficient proof that sweeteners affect gut health at doses for human use. As a result, science must continue to assess their potential effect on the human microbiota in the short and long terms. There are a number of differences between the studies, including dosage, the population assessed and the type of study, which limits the generalization of the results.
Changes in the gut microbiota have been observed in animal studies. Further studies are necessary to assess their potential effects on long-term exposure in humans.
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