Conventional wisdom says that exposing a baby to small amounts of gluten around the age of four to six months may prevent the child from developing celiac disease, but two new studies suggest it makes no difference.
The tests, reported in the October 2 issue of the New England Journal of Medicine, also offer evidence that breast feeding doesn't guard against the autoimmune disease, which attacks the small intestine and affects as many as one in 100 in the United States and the United Kingdom. The condition is much rarer worldwide.
"From now on, it will be hard for anyone to continue to recommend the introduction of gluten specifically at the age of 4 to 6 months," the timetable tested in one of the studies, according to an accompanying editorial by Drs. Jonas Ludvigsson of the Karolinska Institute in Stockholm and Peter Green of the Columbia University College of Physicians and Surgeons in New York City.
Another study found that delaying exposure to gluten until the age of 12 months may delay the onset of celiac disease. However, it ultimately didn't prevent the condition.
In both tests, "The researchers also did not find any evidence that breast-feeding, the duration of breast-feeding, or the introduction of gluten during breast-feeding influenced later development of celiac disease," Ludvigsson and Green wrote.
"That was almost shocking. We didn't expect that at all," said study coauthor Dr. Alessio Fasano, director of the Center for Celiac Research at MassGeneral Hospital for Children in Boston.
"There had been compelling circumstantial evidence that breast feeding would protect, and we were convinced that was the case. But we didn't find any difference whatsoever," Fasano said.
"The only difference - and it made a huge difference in terms of the risk - was the genetic component," Fasano told Reuters Health. "Without those genes, you can't develop celiac disease."
Celiac disease runs in families and a particular genetic variant makes it much more likely a person will develop the condition. In the studies, the infants with that gene profile were considered to be at high risk for celiac.
The concept that limited gluten exposure might prevent the disease in such high risk infants was based on studies that looked at historical data, but it had not been thoroughly tested. "The idea was that delaying the introduction of gluten would allow the immune system to mature so there was less risk of celiac disease," Fasano said. "That turned out not to be the case."
In that study, involving 832 newborns with a close family history of celiac disease, 12 percent introduced to gluten at six months developed overt celiac disease by age two compared to 5 percent of children exposed to dietary gluten at 12 months. But by age five, it didn't matter which group the child had been in. The rate of overt celiac disease was 16 percent in both.
Giving gluten at 12 months "may postpone it, but not prevent it," Fasano said.
In the second study, 944 children were given daily doses of 100 milligrams of gluten or placebo from age four months to six months. At the three-year mark, 5.9 percent in the gluten group and 4.5 percent in the placebo group had celiac disease - an insignificant difference.
"We have not found the preventive strategy we wanted," senior author Dr. Lusia Mearin of Leiden University Medical Center in the Netherlands told Reuters Health. "On the other hand, this advice has been given to thousands of families in the world and this is something we don't need to stress anymore."
"Of course, breast feeding is the best for all the babies, so pediatricians will have to advise that for babies," Mearin said. Yet when it comes to preventing celiac disease, "it doesn't make any difference."
But Dr. Hilary Jericho, an assistant professor of pediatrics at the Celiac Disease Center of the University of Chicago, who was not involved in the research, said despite the quality of the new tests, she's not sure the findings will produce a big change in practice.
The delay seen in Fasano's study when gluten was given later might turn out to be beneficial in the long run.
"I probably would still advise parents to introduce small amounts of gluten leaning toward the six-month mark and continuing to breastfeed, even if these studies haven't shown a significantly protective role," Jericho said. "I think it's still a good protocol to follow."