Daikon Radish, Rats, and Carrot

Sweeteners, Rats, and Babies

Some people really don’t like low calorie sweeteners. So once again we have a wave of fear-mongering headlines. This time, they’re suggesting that pregnant women who consume these sweeteners may harm their babies. The proposed harm is a change in the baby’s microbiome and a higher risk of obesity. The evidence? A study of rats bred for obesity, fed a diet to induce it, and then fed stevia, aspartame, or water. This was a study of 26 rats and 50 offspring. Researchers analyzed the microbiota from 19 of the maternal rats and 12 of the offspring.

Based on observations from these few rats the authors conclude:

“This result has important implications for human health because the diet of mothers during pregnancy and lactation likely also impacts the gut microbiota, microbial metabolites, and the metabolic fitness to their children.”

We note the word likely in their conclusion. This is the clue that the authors are offering speculation, not facts.

Rats Bred and Fed for Obesity

This is an interesting study in the growing field of research on the microbiome. However, translating these results into recommendations for real human mothers facing a flood of information about what they should and shouldn’t do during pregnancy is a bit iffy. The rats in this study were bred for obesity and fed an unhealthy diet of high fat and sugar content. The purpose is to induce obesity.

In these rats, fed and bred in this way, researchers found a difference in microbiota and body weight for offspring.

Substances of Concern in Pregnancy

Nutrition before and during pregnancy is indeed important for the health of a mother and her children. But the fact is that there are much more important issues that deserve attention than sweeteners. First and foremost is the importance of a healthy pattern for eating. Also important is avoiding substances of concern for the health of mother and child. Alcohol, tobacco, and caffeine are real concerns. The American College of OBGyn advises strongly against cannabis in pregnancy.

Sweeteners are not a big concern, though. Most authorities will tell you to avoid saccharine. Stevia and aspartame in moderation seem to present little risk.

So this interesting study is worth considering for what it is – a small study in a population of rats fed and bred for obesity. But it is not a cause for alarm about sweeteners, pregnancy, and the metabolic health of babies.

Click here for the study, here here for uncritical reporting on on it, and here for further perspective on the polarized nature of research on sweeteners.

Daikon Radish, Rats, and Carrot, painting by Shotei Takahashi / WikiArt

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January 27, 2022

3 Responses to “Sweeteners, Rats, and Babies”

  1. January 27, 2022 at 7:01 am, Al Lewis said:

    Studies done in rodents often don’t translate to humans. For instance, years ago it was found that thin mice had more leptin than fat mice. People were clamoring for leptin, but of course it wasn’t commercially available.

    Dave Barry wrote: “Until leptin is available, we should just go find some thin mice and eat them. It can’t be worse than tofu.”

  2. January 28, 2022 at 3:16 pm, Monica Reinagel, MS, LDN said:

    Here’s a study on human mothers (1700 of them), which followed their offspring for 18 years, showing that diet soda consumption during pregnancy was correlated with higher BMI and fat mass in the kids throughout adolescence. Correlation is not causation, to be sure, but there’s more than just a single rat study to support this hypothesis. https://www.nature.com/articles/s41366-021-00897-0

    • January 28, 2022 at 4:54 pm, Ted said:

      Thank you Monica. This is an interesting and relevant study. However, it only documents a correlation, not a cause and effect relationship. I agree with the authors when they conclude that “conclusions about causality cannot be drawn” from this research. The choice to drink non-caloric sweetened beverages is driven not only by BMI, but also by perceived risk of weight gain. Obesity is a highly heritable condition.

      So it could be that a mother’s biological risk of weight gain causes her to be more likely to drink non-caloric sweetened sodas, and also more likely to have children who share their biological predisposition to weight gain. It’s also worth noting that BMIz scores, which this study uses, are not reliable and can “lead to incorrect conclusions” (see https://doi.org/10.1002/oby.23346).