Breast-feeding at age 2 or older increases a child’s risk of severe dental caries by the time they’re 5, independently of how much sugar they get from foods, researchers say.

To investigate the effect of prolonged breastfeeding on children’s teeth, Karen Glazer Peres of the University of Adelaide in Australia and colleagues analyzed data on 1,129 children born in 2004 in Pelotas, Brazil, a community with a public fluoridated water supply.

Breastfeeding information was collected at birth and when children were 3 months, 1 year and 2 years old. Sugar consumption data was collected at ages 2, 4 and 5.

By age 5, nearly 24 percent of children had severe early childhood caries, which researchers defined as six or more decayed, missing or filled tooth surfaces, according to the report in the journal Pediatrics. Close to half of children had at least one tooth surface affected.

Children who had breast-fed for at least two years, which was close to one-quarter of the group, had a higher number of teeth that were decayed, missing or had a filling. Their risk of having severe early childhood caries was also 2.4 times higher compared with those who were only breastfed up to 1 year of age. Breast-feeding for 13 months to 23 months had no effect on dental caries.

To collect data on sugar consumption, the team used a list of food items or food groups consumed the day prior to a clinic visit. At age 2, groups were categorized as “low sugar consumption,” meaning zero or less than twice daily, and “high sugar consumption,” meaning two or more times daily.

But sugar consumption was only associated with a greater risk of having severe early childhood dental caries when children who consumed the highest amount were compared with children who consumed the least.

Subsequent analyses of prolonged breast-feeding, taking into account the pattern of sugar consumption throughout the child’s life course, showed that prolonged breastfeeding was an independent risk for severe caries and decayed, missing or filled teeth, the authors note.

“Breast-feeding is the unquestioned optimal source of infant nutrition. Dental care providers should encourage mothers to breastfeed and, likewise, advise them on the risk,” Glazer Peres told Reuters Health by email.

“General recommendations such as drinking fluoridated water as well as cleaning a child’s teeth with fluoridated toothpaste before going to bed may help to prevent dental caries,” she said. “These approaches are in line with most of the guidelines for practice and policy recommendations worldwide.”

“There is no question that babies who breast-feed for a longer time than recommended by the American Academy of Pediatric Dentistry or the American Academy of Pediatrics have an increased cavity rate,” noted Dr. Robert Morgan, chief of dentistry at Children’s Health in Dallas, Texas, who was not involved in the study.

“The issue is not entirely related to breast feeding. Babies who sleep with a bottle of milk or take a sippy cup of milk throughout the day or night also have an increased incidence of caries,” he said by email.

“The real correlation of breast-feeding is perhaps the number of exposures to food and drink that a child has during the day and night due to the ease of access to mom,” he explained.

“We know that after a baby eats or drinks there is a rise in bacteria and a rise in decay potential for approximately 20 minutes, (after which) bacterial growth and concurrent acid production decreases, as does the decay potential. Therefore, we recommend toddlers eat breakfast, lunch and dinner with perhaps a mid-morning snack and a mid-afternoon snack. If a parent brushes (the child’s teeth) after breakfast and dinner there are only three exposures to increased decay rate times,” Morgan said.

“In my practice, for the mothers who would like to breast-feed for a longer period, we advise them to follow the recommended feeding schedule regardless of the feeding methods, whether breast, bottle or cup – feed and drink a non-water drink no more than five times a day and never at night – and we encourage the brushing schedule (after breakfast and dinner feeding),” he said.