Sweeteners during pregnancy may affect a baby’s gut microbiome

Sweeteners during pregnancy may affect a baby’s gut microbiome
© iStock/Dejan_Dundjerski

A new study investigates the link between consuming sweeteners during pregnancy and a child’s risk of obesity and changes in their gut microbiome.

The researchers found that when they fed pregnant rats with stevia or aspartame, when they gave birth to pups, they had a higher risk of obesity and specific changes in their gut microbiome, potentially highlighting how essential maternal nutrition is during pregnancy and the implications on unborn babies.

The study discovered that when rat mothers consumed sweeteners during pregnancy, their offspring tended to have a higher percentage of body fat. The rat pups showed changes in gut microbial communities, with increases in propionate- and butyrate-producing microbes and reductions in lactose-fermenting species, which could explain the weight gains. The results suggest that maternal diet during pregnancy can significantly affect obesity risk in children.

The new study in Frontiers in Nutrition asked the question of whether artificial sweeteners increased obesity risk for an unborn child and possibly changed the gut microbiome.

The effects of sweeteners on gut microbiome

Many people use low-calorie sweeteners as a healthier alternative to sugar, but they may have some unexpected effects in pregnancy. Sweeteners can be found in soft drinks, jams, and toothpaste. Whilst, they are largely non-toxic in adults, previous research suggested that prenatal consumption by mothers can affect obesity risk and the gut microbiome in infants. However, no one had examined this in detail to understand the specific changes in microbial populations and their potential link to obesity.

“We know that a mother’s diet during pregnancy plays an extremely important role in determining whether their offspring will develop certain diseases later in life,” said Prof Raylene Reimer of the University of Calgary, and senior author of the study.

“In this study, we were interested in determining how consuming low-calorie sweeteners during pregnancy, specifically the artificial sweetener aspartame or the natural alternative stevia, affected the gut bacteria and obesity risk of offspring.”

To investigate this, the researchers fed aspartame, stevia or plain water to pregnant rats. Once the rats gave birth, the researchers weighed the rat pups and investigated their gut microbiomes to assess how the sweeteners had affected them.

Minimal effect in mothers

Surprisingly, the sweeteners had minimal effects on the rat mothers but had significant effects on their offspring. The pups born of sweetener-fed mothers gained more weight, had a higher body fat percentage, and showed key changes in their gut microbiomes, with increases in propionate- and butyrate-producing microbes and reductions in lactose-fermenting species. These changes in microbial fermentation in the gut may have caused weight gain in the pups.

“Even though the offspring never consumed the low-calorie sweeteners themselves, their gut bacteria and obesity risk were influenced by the sweeteners that their mothers consumed during pregnancy,” said Reimer.

“We found that specific bacteria and their enzymes were linked to how much weight the offspring gained and how much body fat they accumulated.”

Due to the study being performed in rats, it is not directly applicable to humans, but previous human studies have shown a similar link between consuming sweeteners during pregnancy and higher infant body mass index. Further research is needed to provide clearer guidance for mothers.

“A mother’s diet during pregnancy is very important for the short- and long-term health of their infants,” said Reimer. “Following dietary guidelines and staying within the recommended weight gain guidelines for pregnancy are key steps to take.”

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