Babies seem to be born with a sweet tooth–one that many adults retain. However, parents and caregivers who indulge a child's appetite for sugary drinks may be fostering cavities in their children's teeth, a new study finds.
That idea may seem like a no-brainer, acknowledges nutritionist Teresa Marshall of the University of Iowa College of Dentistry. However, she notes, there have been almost no published data to prove this, except for a few studies focusing on fruit juice. Her new data from a group of 642 Iowa children–all followed via dietary surveys from birth through ages 4 to 7–not only confirmed suspicions that other sweet drinks aren't benign, but even turned up a surprise.
In terms of a sweet drink's impact on cavities, Marshall says, "I would have expected any sugared beverage would be a problem." Certainly, she notes, that's what previous studies have suggested. But to her surprise, two types of drinks emerged as even worse for the teeth than juice is.
The study linked consumption of soft drinks most strongly to cavities. Among kids whose parents or other caregivers reported that the child regularly consumed soft drinks, the likelihood of having at least one cavity by school age was double that of kids reported to drink no soda pop. The next most cavity-fostering beverages appeared to be those prepared from sweet, powdered mixes. Equally sweet fruit juices and juice-based drinks appeared to pose less of a cavities risk. And milk revealed no link to cavities.
Marshall says her new findings are particularly troubling because there has been a trend over the past few decades for children–even toddlers–to drink less milk and more soft drinks.
A sweet-and-sour trend
The U.S. Department of Agriculture has long surveyed what U.S. residents eat, and many researchers have mined these data for trends. One clear pattern that's emerged among children is a substitution of sweetened drinks for milk.
For instance, Marshall notes, one study found that between the late 1970s and mid-1990s, the per-child consumption of sweetened soft drinks rose 74 percent among boys and 65 percent among girls. Over that same period, the proportion of kids drinking milk daily dropped. For instance, among girls, the share of milk drinkers fell from 72 percent to 57 percent. Other reports showed that as kids' milk consumption declined, intake of soft drinks climbed.
In the past, most nutritionists have focused on the implications of these trends for calcium intake and, in turn, bone health. For instance, a study by Alanna J. Moshfegh and her coworkers with the USDA's Agricultural Research Service found that in the mid-to-late-1990s, the average U.S. preschooler was drinking a half-serving less of milk per day than 5 years earlier–down to 11.5 ounces (327 grams) per day. Over that same period, other USDA scientists reported increasing soft-drink consumption among children. In 1994, a USDA survey showed that about half of preschoolers consumed soda pop, some averaging 9 or more ounces daily.
In the study of milk consumption, Moshfegh and her coworkers noted that only 40 percent of kids drinking soda pop or juice with lunch were meeting the recommended daily intake of calcium. In contrast, nearly three-quarters of the children who drank milk with their lunch were getting their daily calcium. The researchers concluded that young soda drinkers could be establishing habits that would jeopardize the health of their developing bones.
USDA scientists Cecilia Wilkinson Enns, Sharon J. Mickle, and Joseph D. Goldman reported last year in Family Economics and Nutrition Review that in the late 1970s, "children drank about four times as much fluid milk as any other beverage." Twenty years later, the researchers found, kids were drinking "only about 1.5 times as much milk as soft drinks." That trend is jeopardizing children's intake of calcium and certain vitamins–and perhaps fostering childhood obesity–the researchers concluded.
Both are valid concerns, says Marshall, but she's focusing on cavities, or dental caries. Tooth decay is the most common chronic infection in childhood, she points out. Teeth are eroded by acids coming from bacteria that thrive on sugars in the mouth.
Dental sealants don't help
Many parents send their children to the dentist for periodic applications of dental sealant–essentially a plastic coating for the grinding and biting surfaces. However, Marshall points out, it's the unsealed fronts and backs of teeth that are most vulnerable to bacteria that thrive on sugary beverages.
In her new study of Iowa children, the proportion with cavities by study's end was about equal for soda drinkers and kids getting a sweetened drink from a mix. However, soda drinkers had more tooth surfaces exhibiting damage from caries than did kids who regularly got a drink from a mix.
Marshall says she's perplexed by soft drink and powdered-drink consumption correlating with more tooth decay than juice consumption did. There might be something about the combination of sugars and acids in sodas and mixes that makes them especially hard on teeth. Or, kids might drink them differently than they do juices, with sodas and mixes being consumed regularly between meals and juices being a more frequent mealtime beverage. Between-meal drinks are worse for teeth, says Marshall, since foods tend to scrub a beverage's sugars from teeth. Also, she speculates, diligent parents might send the kids off to brush after a meal, but not after snack time.
Clearly, Marshall says, this topic is ripe for further study.
Teresa A. Marshall
Department of Preventive and Community Dentistry
College of Dentistry
University of Iowa
Iowa City, IA 53342-1010
USDA Agricultural Research Service
Beltsville Human Nutrition Research Center
Food Surveys Research Group
Beltsville, MD 20705
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