Artificial Sweeteners During Pregnancy and Your Baby’s Microbiome

As a nutritionist, one of my (many) areas of interest is in research about the relationship of diet to health.  Today’s research, conducted  by scientists in Canada, actually shocked me.[i]  I did not know that the consumption of artificial sweeteners by pregnant women is associated with an increased risk of infant obesity.  I knew, obviously, that the stuff isn’t good for any of us, but that it could affect a fetus/infant was very surprising to me.

Firstly, some staggering statistics.  Between the years 1978 and 2016, childhood obesity in the USA increased from 5% to 18.5%. That’s just obesity and does not include those who are overweight.  Almost 20% of children in the country are OBESE.  Holy cow.  Secondly, a fairly recent study showed an association between maternal consumption of artificial sweeteners during pregnancy and a higher BMI (body mass index) in babies under a year old – and this risk factor was independent of other known risk factors, like higher maternal BMI, smoking, poor diet, maternal diabetes, short breastfeeding duration, and early introduction of solid foods.  We know that artificial sweeteners affect the gut microbiome and in animal studies, those changes led to glucose intolerance.  In animals too, it’s been noted that exposure to such sweeteners during pregnancy led to changes in the babies, including a decrease in Akkermansia municiphila.  However, the mechanism of action had not yet been described.

This study was designed to figure out that mechanism of action and to do so, they decided to look at the main suspect:  the infant microbiome during the first year of life.  The study comprised 100 babies:  50 with mothers who did not consumer artificial sweeteners and 50 whose mothers did so on a daily basis.  What did the findings show?  Maternal consumption of artificial sweeteners led to shifts in the gut bacteria in the babies, including a depletion of several Bacteroides species.  They also found subsequent changes in several metabolites.  For example, in exposed infants, urine succinate was higher at 3 months of age and was positively associated with a higher BMT at 1 year of age.  In fact, succinate was found to mediate 29% of the effect of artificial sweetener exposure on BMI at a year old, meaning that this metabolite may be crucial in leading to the increased weight of babies and a factor in the “unprecedented rise in childhood obesity.”

To sum up their results:  “…our results suggest that maternal consumption of ASB [artificial sweeteners] during pregnancy (1) may influence the establishment of the infant gut microbiome in infants diverging from what has previously been described as the typical microbiome maturation trajectory and (2) is associated with an increase in infant BMI at one-year-old that may be mediated by succinate.”  The impact on obesity of artificial sweeteners is smaller than other factors, like breast feeding for example, but it was linked to differences in urine metabolites that support the notion of these gut biome changes leading to early-life predisposition toward metabolic diseases.

The authors go on to point out that the first year of life is considered particularly crucial in microbiome development (i.e. a “’window of opportunity’ for training of the immune system through interactions between host cells, gut microorganisms, and microbial metabolites”) and that factors that lead to early dysbiosis are therefore, particularly detrimental.

There is no recommendation at this point to avoid such sweeteners during pregnancy as more research is needed first, but personally, were I having children now, I’d be doing everything I could think of to protect my baby’s microbial health!

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[i] Laforest-Lapointe I, Becker AB, Mandhane PJ, et al. Maternal consumption of artificially sweetened beverages during pregnancy is associated with infant gut microbiota and metabolic modifications and increased infant body mass index. Gut Microbes. 2021;13(1):1-15. doi:10.1080/19490976.2020.1857513