A high gluten intake by mothers during pregnancy is associated with an increased risk of their child developing type 1 diabetes, suggests a study. However, the researchers say that further studies are needed to confirm or rule out these findings before any changes to dietary recommendations could be justified.
Gluten is a general name for the proteins found in wheat, rye, and barley and is suggested to affect the development of type 1 diabetes. In animal studies, a gluten free diet during pregnancy almost completely prevented type 1 diabetes in offspring, but no intervention study has been undertaken in pregnant women.
To better understand the nature of this association, researchers led by Julie Antvorskov at the Bartholin Institute in Denmark in collaboration with researchers at the Statens Serum Institut, set out to examine whether gluten intake during pregnancy is associated with subsequent risk of type 1 diabetes in children.
They analysed data for 63,529 pregnant women enrolled into the Danish National Birth Cohort between January 1996 and October 2002.
Women reported their diet using a food frequency questionnaire at week 25 of pregnancy and information on type 1 diabetes in their children was obtained through the Danish Registry of Childhood and Adolescent Diabetes.
Average gluten intake was 13 g/day, ranging from less than 7 g/day to more than 20 g/day, and the researchers identified 247 cases of type 1 diabetes (a rate of 0.37%) among the participants’ children.
After taking account of potentially influential factors, such as mother’s age, weight (BMI), total energy intake, and smoking during pregnancy, they found that the child’s risk of type 1 diabetes increased proportionally with the mother’s gluten intake during pregnancy (per 10 g/day increase).
For example, children of women with the highest gluten intake (20 g/day or more) versus those with the lowest gluten intake (less than 7 g/day) had double the risk of developing type 1 diabetes over a mean follow-up period of 15.6 years.
This is an observational study, so no firm conclusions can be drawn about cause and effect. However, the researchers say this was a high-quality study with a large sample size, and they were able to adjust for a number of factors that could have affected the results.
The mechanisms that might explain this association are not known, but could include increased inflammation or increased gut permeability (so-called leakiness of the gut), they write. However, more evidence is needed before changes to dietary recommendations could be justified, they conclude.
In a linked editorial, researchers at the Finnish National Institute for Health and Welfare, say further studies are needed “to identify whether the proposed association really is driven by gluten, or by something else in the grains or the diet.”
The authors agree that it is too early to change dietary recommendations on gluten intake in pregnancy, but say doctors, researchers, and the public “should be aware of the possibility that consuming large amounts of gluten might be associated with an increased risk for the child to develop type 1 diabetes, and that further studies are needed to confirm or rule out these findings, and to explore possible underlying mechanisms.”
The Guardian reports that David Sanders, professor of gastroenterology at the University of Sheffield who was not involved in the study, welcomed the research saying that incidence of coeliac disease appears to have risen since the 1950s, possibly because of increasing levels of gluten consumption in society. But he said the study suggests the risk of type 1 diabetes among offspring of women eating high levels of gluten is still small, and that the increased risk was only modest and that with one slice of bread containing about 2.5g of gluten, the highest gluten group of pregnant women were eating a very large quantity of such foods.
Dr Jessica Biesiekierski, an expert in human nutrition from La Trobe University, said it was not known whether any of the women or children had coeliac disease, which is often undiagnosed but can be inherited and has been linked to a greater risk of developing type 1 diabetes.
“If anyone is concerned that they may have diabetes or coeliac disease, that they should see their doctor followed by a dietitian,” Biesiekierski added, pointing out that a gluten free diet can be lacking in nutrients including fibre, iron and B-vitamins.
Objective: To examine the association between prenatal gluten exposure and offspring risk of type 1 diabetes in humans.
Design: National prospective cohort study.
Setting: National health information registries in Denmark.
Participants: Pregnant Danish women enrolled into the Danish National Birth Cohort, between January 1996 and October 2002,
Main outcome measures: Maternal gluten intake, based on maternal consumption of gluten containing foods, was reported in a 360 item food frequency questionnaire at week 25 of pregnancy. Information on type 1 diabetes occurrence in the participants’ children, from 1 January 1996 to 31 May 2016, were obtained through registry linkage to the Danish Registry of Childhood and Adolescent Diabetes.
Results: The study comprised 101 042 pregnancies in 91 745 women, of whom 70 188 filled out the food frequency questionnaire. After correcting for multiple pregnancies, pregnancies ending in abortions, stillbirths, lack of information regarding the pregnancy, and pregnancies with implausibly high or low energy intake, 67 565 pregnancies (63 529 women) were included. The average gluten intake was 13.0 g/day, ranging from less than 7 g/day to more than 20 g/day. The incidence of type 1 diabetes among children in the cohort was 0.37% (n=247) with a mean follow-up period of 15.6 years (standard deviation 1.4). Risk of type 1 diabetes in offspring increased proportionally with maternal gluten intake during pregnancy (adjusted hazard ratio 1.31 (95% confidence interval 1.001 to 1.72) per 10 g/day increase of gluten). Women with the highest gluten intake versus those with the lowest gluten intake (≥20 v <7 g/day) had double the risk of type 1 diabetes development in their offspring (adjusted hazard ratio 2.00 (95% confidence interval 1.02 to 4.00)).
Conclusions: High gluten intake by mothers during pregnancy could increase the risk of their children developing type 1 diabetes. However, confirmation of these findings are warranted, preferably in an intervention setting.
Julie C Antvorskov, Thorhallur I Halldorsson, Knud Josefsen, Jannet Svensson, Charlotta Granström,Bart O Roep, Trine H Olesen, Laufey Hrolfsdottir, Karsten Buschard, Sjudur F Olsen