Extra half slice of bread a day may increase chance of celiac disease in at-risk children

At-risk kids found increasingly likely to get celiac disease the more gluten they ate before age of 5

By Amy Ratner, Medical and Science News Analyst

At-risk children who eat higher amounts of gluten before they are five years old have an increased chance of developing celiac disease, according to a new international study.

A genetically at-risk child who eats more than 2 grams of gluten per day, at about age 2 had a “significantly increased risk” of celiac disease, the study found. Two grams is equal to about a slice of white bread. For every 1 gram of extra gluten per day, the chance of developing celiac disease went up 7 percent. One gram is equal to about a half slice of white bread or one serving of pasta.

The study, published recently in the Journal of the American Medical Association (JAMA), included more than 6,600 children with the genes associated with celiac disease from the United States, Finland, Germany and Sweden. The amount of gluten they consumed was determined through food diaries filled out periodically by their parents.

In addition to celiac disease, researchers found a 6 percent increase in the risk for celiac disease autoimmunity, which can be an early sign of celiac disease but does not always lead to its development. In the study, children who had positive results in two consecutive blood tests for celiac disease antibodies were considered to have celiac autoimmunity.

Both celiac autoimmunity and celiac disease peaked when children where 2 to 3 years old.

“In my opinion, children who have a first-degree relative with celiac disease — a mother, father or sibling — may have to be careful with high intakes of gluten in the diet,” said Carin Andrén Aronsson, PhD, a lead author of the study and study manager of the diabetes and celiac disease unit, Lund University, Sweden. Children who do not have a first degree relative should eat a “normal diet,” she said, noting the difficulty of getting enough vitamins, minerals and dietary fiber on the gluten-free diet.

Aronsson cautioned that although the study noted a relationship between more than 2 grams and increased risk, the research did not test for a safe level of gluten. “This needs to be done in clinical trials on populations from different countries,” she said.

More study needed

Celiac disease experts who were not involved in the study advised parents of at-risk children not to try to fine tune their children’s diets to meet precise gluten limits until additional research is done.

“These results are intriguing and should inspire larger studies to further explore this finding,” Maureen Leonard, MD, and Alessio Fasano, MD, of the Center for Celiac Research and Treatment, Boston, wrote in an editorial in JAMA. “However, the amount of gluten ingested during the first 5 years after birth cannot completely explain the increased prevalence of celiac disease.”

Other factors, including genetic predisposition, changes in exposure to viruses and changes in the intestinal microbiome must be at play, the editorial said.

Leonard and Fasano wrote that one of the main concerns is that reducing the amount of gluten a child eats could also reduce the amount of whole grains and fiber that are part of a healthy diet.

The editorial said there is “a fine balance” between a possible advantage of a reduced amount of gluten for an at-risk child and the potential for increasing chances the child will develop chronic health problems related to a lack of whole grain and fiber, which are already inadequate in the Western diet. Leonard and Fasano noted it is too early to recommend changes in the way gluten is introduced in the diet of at-risk children.

A parent’s view

“The study will be in my mind as we introduce new foods,” said Erin Smith, who was diagnosed with celiac disease as a toddler and has a 5-month-old baby. She and her husband have already decided to include gluten-containing food in her son’s diet when he begins eating solid food, based her personal knowledge about celiac disease and her pediatrician’s support of the decision. She expects her baby will naturally eat low amounts of gluten because of her gluten-free diet and the fact that her husband is from Mexico, where gluten-containing food was not a big part of his diet growing up.

“I feel that it is important for the baby to be consuming gluten until he shows any signs of possible symptoms of celiac,” said Smith, an established gluten-free blogger who has a good understanding of the reactions to look for. “We will definitely monitor his gluten consumption, but I can’t imagine him eating more than 2 grams a day based on our overall diet anyway.”

Children who have a first degree relatives with celiac disease are more likely to have the HLA DQ2 and DQ8 genes found in nearly everyone who has c celiac disease. The genes are also found in about 40 percent of the general population, while only 1 percent has celiac disease. Since the genes alone do not always result in celiac disease, researchers have been looking at environmental factors that might trigger the condition in some but not others.

Study details

Study participants were part of The Environmental Determinants of Diabetes in the Young (TEDDY) study, a broad investigation designed to identify environmental triggers that cause type 1 diabetes and celiac disease, both of which are genetic autoimmune conditions.

The amount of gluten the children consumed was estimated from three-day food diaries collected just before a scheduled clinic visit at six, nine and 12 months and then twice a year until the age of 5.

Although the food records provide only a partial picture of what children in the study ate, Aronsson said the large number of children in the study gave researchers a representative sample of the diet of children at different ages.

Parents were instructed on how to estimate food portion sizes and to follow their children’s normal food habits during the period being documented. Researchers then analyzed how much gluten was likely to be in the foods noted in the diaries. Blood tests for anti-tissue transglutaminase (TTG), antibodies found in the blood when someone who has celiac autoimmunity or celiac disease consumes gluten, were measured beginning at the two-year study visit.

The study found that of the 6,600 participants, 1,216 had celiac disease autoimmunity and 447 had celiac disease diagnosed at a median age of about 3 years. About 17 percent of the children with celiac disease and about 10 percent of those with celiac disease autoimmunity had a first-degree relative with celiac disease. Celiac disease was diagnosed in children who had either a biopsy showing intestinal damage or TTG levels at a consistently high enough level to meet European pediatric diagnosis standards.

In addition to the large number of children in the study, the fact that they came from four countries with a variety of eating habits, and the way in which researchers were able to capture changes in what children ate as they grew and before they developed celiac disease, were cited by authors as strengths of the study.

Limitations of the study include challenges in analyzing gluten content of foods included in the food diaries and relying on the diaries to estimate the amount of gluten in a child’s diet. The study calls for a follow-up randomized clinical trial of different amounts of gluten eaten by children.

Role of the amount of gluten

Previous studies have also found that the amount of gluten might determine whether an at-risk child develops celiac disease.

The University of Chicago Celiac Center earlier this year recommended new guidelines that call for reduced amounts of gluten when food is being introduced to infants, and the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) in 2016 recommended that consumption of large amounts of gluten be discouraged during the first few months after gluten is introduced in an at-risk infant’s diet.

The University of Chicago guidelines say that at-risk infants should eat less than 5 grams of gluten-containing food on average per day beginning when food is introduced to a baby at 4-to-6 months and continuing until the age of 2.

Researchers have been trying to pinpoint the effect gluten in the diet of infants has on development of celiac disease for a number of years. They’ve tested theories of whether breast feeding or when a baby begins to eat gluten make a difference. After extensive study, they have concluded neither of these matters. Meanwhile, the amount of gluten in a child’s diet has been getting more research attention.

You can read the study here.