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The Checkup
Information is limited about the long-term safety of consuming nonnutritive sweeteners.
Even the name, “nonnutritive sweeteners,” sounds like it was invented to avoid, well, sugarcoating the issue. We used to call them artificial sweeteners; this new term is intended to emphasize that they have no nutritional content — no vitamins, no minerals, no calories, or very few (that’s the whole point).
We evolved to like sugar and sweet tastes precisely because they signal the presence of calories — that is to say, food that our bodies can burn for energy.
Now, we are more likely to be worried about consuming too many calories — and whether our children are overdosing on sugar.
The American Academy of Pediatrics put out a policy statement in November on the place of these nonnutritive sweeteners in children’s diets, noting that there are now more of them in foods and other products on the market, and that therefore children and adolescents are consuming more of them — and this is happening in the absence of clear data about whether they help with weight control, or how they affect children’s tastes as they grow.
“First and foremost, the information we have regarding nonnutritive sweeteners and long-term safety is limited,” said Dr. Carissa Baker-Smith, the lead author of the statement, who is an associate professor of pediatric cardiology at the University of Maryland School of Medicine.
There have been scares in the past about whether certain nonnutritive sweeteners can be carcinogenic, especially in large doses, but in the literature that was reviewed for the policy statement, no such association has been demonstrated.
Allison Sylvetsky, an assistant professor in the department of exercise and nutrition science at George Washington University whose research focuses on this group of sweeteners, said that “while we know that these nonnutritive sweeteners are safe from a toxicological viewpoint, we don’t know if they’re effective for lowering calories and helping kids reduce sugar intake.”
Parents are concerned about the right nutritional balance for their children, Dr. Baker-Smith said, but also often worry more specifically about making sure that their children don’t get too much sugar, worrying about obesity, diabetes, high cholesterol. But consuming nonnutritive sweeteners has not been shown to lead to healthier weight in children, though they may have a place in a larger weight control plan.
Dr. Sylvetsky pointed to one trial published in 2012, done in children ages 6 to 12 in the Netherlands, in which some children were given sugar-sweetened drinks and others got diet beverages. In that study, in which the children were of normal weight, those who were given the diet drinks gained less weight over time than those who were given drinks sweetened with sugar; however, there was no group given unsweetened drinks for comparison.
Some studies in adults suggest it can be helpful to replace sugar-sweetened beverages with diet soda, but in the context of a more comprehensive behavioral weight loss program. “It’s not just, here’s a diet soda, drink this instead,” Dr. Sylvetsky said.
On the other hand, other research suggests that many people use the nonnutritive sweeteners and continue to consume sugar as well. In a study by Dr. Sylvetsky and her colleagues, using survey data, “kids that consumed low-calorie sweetened beverages actually had considerably higher total energy intake and added sugar intake compared to kids drinking unsweetened beverages,” she said. Their reported total calorie intakes were similar to those of the children who reported drinking sugar-sweetened drinks.
This kind of cross-sectional study shows an association, but cannot possibly explain cause and effect. Maybe the kids who drink the diet beverages are also eating snack foods and fast foods — that is to say, maybe drinking a lot of diet drinks is a marker for a less healthy lifestyle overall. But there have also been concerns, some connected to animal studies, that incorporating the nonnutritive sweeteners may have some biological effects on the child’s appetite or metabolism.
We also don’t know, Dr. Sylvetsky said, how different amounts of these sweeteners may affect the young, perhaps influencing their taste preferences, or the bacterial flora in their guts. Taste preferences begin to develop in utero, reflecting substances present in the amniotic fluid, and continue to develop in infancy and after.
“There are a lot of questions that have yet to be answered with respect to early exposure,” she said.
In a 2017 article on how the perception of sweet taste develops in children, Dr. Sylvetsky and her colleagues reviewed possible mechanisms by which exposure to the nonnutritive sweeteners early in life may affect children later on, including the question of whether too much sweetness early on tends to lead children to develop unhealthy diets — and ended by concluding that much more research is needed.
Infants born to mothers who consumed diet beverages were heavier at 1 year of age than those whose mothers avoided the sweeteners in a 2016 study, Dr. Sylvetsky said — even after controlling for other factors like the mother’s weight. Nonnutritive sweeteners are also transferred to nursing infants through breast milk, she said, though at a very low concentration.
If a parent is concerned about a child’s weight, Dr. Sylvetsky said in an email, “I would encourage replacement of sugar-sweetened beverages with unsweetened alternatives such as plain water, rather than simply switching from sugar-sweetened beverages to diet beverages containing nonnutritive sweeteners. An occasional sweet beverage, whether sugar-sweetened or diet, is fine, but the focus should really be on improving the overall diet.”
“What we want to instill is not, replace sugary food with nonnutritive sweeteners, but teach healthier behaviors,” Dr. Baker-Smith said. “Exercise 150 minutes out of the week, choose vegetables at meals, and fruit, appropriate portion size, not an adult-size plate.” She doesn’t see the nonnutritive sweeteners as necessarily beneficial over the long term.
“We should go back to the way we thought about sweets a long time ago, as a treat,” Dr. Baker-Smith said. “One sweet, once a week, not every meal.” And in that context, stick to real sugar for the treats, and avoid all sweetened beverages. That’s what she tries to do for herself and her own kids, she said. “I have gone to avoiding nonnutritive sweeteners for my own family, and I want parents to make the choice for themselves.”
The other message to parents is that to make these choices, we have to read labels — and the labels don’t have enough information. Because six of the eight sweeteners approved by the Food and Drug Administration are considered food additives, manufacturers are required only to state on the label that they are present, not to specify the quantity. Better, clearer labeling would help, she said. “This policy statement is really advocating that the F.D.A. make it clear how much nonnutritive sweetener is in each product, so parents can make informed decisions.”
These sweeteners turn up in an increasing number of places, from toothpaste to breakfast pastries. “If a product says low sugar or sugar-free, that likely means it contains a nonnutritive sweetener,” Dr. Baker-Smith said. “We have to all be aware of how much we’re taking in.”