While they are largely non-toxic in adults, previous research suggests that prenatal consumption by mothers can affect obesity risk and the 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.
To investigate this, 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.
Strikingly, the sweeteners had minimal effects in the rat mothers, but had significant effects in 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. Researchers found that specific bacteria and their enzymes were linked to how much weight the offspring gained and how much body fat they accumulated.
The study was performed in rats, and so isn’t 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 will provide clearer guidance for mothers, but for now, it may be worth giving the sweeteners a miss while pregnant.
A mother’s diet during pregnancy is very important for the short- and long-term health of their infants. Following dietary guidelines and staying within the recommended weight gain guidelines for pregnancy are key steps to take.