Don't Tie Kids' Obesity to Artificial Sweetener Use in Pregnancy

shutterstock_156395255Yes, we've heard it all before — sugar causes obesity, and use of artificial sweeteners also causes obesity. Now some Canadian researchers have supposedly taken this one step further, claiming a link between a woman's consumption of beverages sweetened with artificial sweeteners (think aspartame or cyclamates) and their babies' propensity for overweight and obesity at one year of age.

Their study, "Association Between Artificially Sweetened Beverage Consumption During Pregnancy and Infant Body Mass Index," was recently published in JAMA Pediatrics.

Led by Dr. Meghan B. Azad from Department of Pediatrics and Child Health, University of Manitoba and Children’s Hospital Research Institute of Manitoba, both in Winnipeg, the researchers examined data from nearly 3,000 mother-baby pairs from the Canadian Healthy Infant Longitudinal Development (CHILD) Study, a population-based birth cohort that recruited healthy pregnant women from 2009 to 2012.

During the second or third trimesters of their pregnancies, the women completed dietary assessments using food frequency questionnaires, including artificially sweetened beverages (ABS) and sugar-sweetened beverages (SSB). From those questionnaires the investigators calculated the women's calorie intake and classified their beverage consumption per week as never, <1 per month, 1 or more per week, 2-6 per week, or 1 or more per day. They also evaluated the participants' diets with respect to the Healthy Eating Index (HEI), a measure of diet quality. Then, when the infants were 1-year old, they were weighed and measured and their BMIs were calculated. Each baby's z-score1 for its BMI was also calculated, and a z-score greater than the 97th percentile for that child's gender put him or her into the obese category.

About 30 percent of the mothers reported drinking ABS during pregnancy (about 5 percent drank them daily); and over 77 percent reported drinking SSB with 23 percent consuming them daily. Greater intakes of both ASB and SSB consumption were associated with maternal smoking, higher maternal BMI, lower maternal diet quality, and shorter breastfeeding duration.

The main result was  a statistically significant association between the mothers' reported intake of artificially sweetened beverages and the risk of obesity in their offspring at 1 year of age for those babies whose moms reported drinking 1 or more ASB per day, even when the data were controlled for the moms' BMI. There was no such link between drinking SSB and infants' later BMI status. Further, the relationship between ASB and infants' z-scores was significant only in male babies. And finally, what were those fatter babies eating in the year between birth and their BMI assessment? Did their diets differ from those of slimmer kids?

So should pregnant women be warned against drinking ASB or using artificial sweeteners at all to protect their babies from later overweight or obesity? Not based on this study. First, these data provide only an association — they cannot be said to show a causal link. Further, the number of mothers who consumed the greatest amount of ASB (over one per day) was small compared to the total number of participants — for example, in the nearly 1300 women who had male babies, only 71 said they drank one or more ASB per day, while nearly 900 said they drank fewer than one per month. And, as we have discussed before, self-reported dietary data are prone to memory lapses and biases.

So although it may be tempting for some to blame ASB for the obesity epidemic, there really is a paucity of solid data to support that contention. But if you enjoy climbing on bandwagons, the "blame artificial sweeteners" for everything from cancer to obesity has plenty of room.

1The absolute value of z represents the distance between the raw score and the population mean in units of the standard deviation. z is negative when the raw score is below the mean, positive when above.