**This is the first guest post on my page by Cristen Pantano, an incredibly talented scientist and mother of two children. Her youngest child was diagnosed with Celiac disease earlier this year. Many thanks to Cristen for tackling this challenging topic!
Celiac is known to have a large genetic component and people with Celiac disease carry the HLA-DQ2 or HLA-DQ8 genes. However, only around 4% of people that carry these genes develop Celiac (http://www.ncbi.nlm.nih.gov/pubmed/20419830). The big question then is, what else is contributing to the development of Celiac?
Scientists are currently looking at other candidate genes, and so far, seven additional genes that make individuals more susceptible to developing Celiac have been identiﬁed. Genes are a great place to start, but as we all know, gluten is the big culprit in Celiac. It is the known environmental “trigger” for Celiac. Why is it that some people that carry the “Celiac genes” develop the disease after gluten exposure while others don’t?
Scientists and doctors are asking this question a lot these day. One area that is being investigated is infant feeding. Studies looking back on the Swedish Celiac epidemic of the 1980-1990s have shown that more than half of the epidemic could be explained by infant feeding practices (http://www.ncbi.nlm.nih.gov/pubmed/?term=swedish+celiac+epidemic+review). During the time of the epidemic, Swedish infants were being introduced to gluten, on average, at around ﬁve months of age. Breastfeeding ended around this time and was replaced with formula thickened with wheat ﬂour. When breastfeeding averages extended toward seven months and the popularity of wheat-laden formulas decreased, so did the rates of Celiac.
The Swedish epidemic got researchers thinking about infant feeding and many studies have since been published showing an effect of the age of gluten introduction, the amount of gluten introduced, and breast feeding on Celiac development.
A new study looking at the effect of these factors on the development of Celiac was recently published in the journal Pediatrics (http://www.ncbi.nlm.nih.gov/pubmed/24101761). This study, out of Norway, looked at the early feeding practices in 324 children that developed Celiac disease compared to a cohort with 81,843 children that did not develop the disease. The strength of the study is that it was prospective. Unlike most population studies where parents have to look back in time and remember details of early milestones, in a prospective study, parents ﬁll out surveys to provide information in real time.
So what did this most recent study ﬁnd? The authors found that 3.68/1000 children developed Celiac when introduced to gluten at six months compared to 4.24/1000 when introduced at four months and 4.15/1000 after six months. The increased risk for Celiac disease when gluten is introduced before four months, or after six, has been previously observed (http://www.ncbi.nlm.nih.gov/pubmed/17664902).
In this new study, the average length of breastfeeding in children that developed Celiac was 10.4 months compared to 9.9 months in the control population. The researchers found a positive association of prolonged (greater than 12 months) breastfeeding and the development of Celiac disease. When all their breastfeeding data was adjusted for confounding factors such as maternal Celiac disease, this increased risk was borderline signiﬁcant. That means that statistically speaking, the data set is on the weaker side and needs to be interpreted with caution. However, it does still demonstrate that in this data set, children that were nursed for twelve months or more had a greater risk for developing Celiac.
These ﬁndings have been met with frustration by many mothers of children with Celiac. Are women responsible for the development of their child’s Celiac disease because they chose to hold off solid foods and nurse up to, or past, one year? Of course they aren’t, and the authors of this study are not saying that they are. In their discussion, the authors caution that while their data on age of gluten introduction closely matches data from earlier studies, their data on breastfeeding does not.
Many, if not all, previous studies looking at breastfeeding and Celiac disease have found a protective effect from nursing. A 2006 review of the literature found that breastfeeding at the time of gluten introduction provided a 52% reduction in the development of Celiac disease (http://www.ncbi.nlm.nih.gov/pubmed/16287899). In 2005, two Swedish studies found a signiﬁcant reduction in the onset of Celiac in babies that were nursed at the time of gluten introduction and continued to be nursed after that ﬁrst introduction (http://www.ncbi.nlm.nih.gov/pubmed/18806718).
This latest study found that breastfeeding did not protect against Celiac and that nursing past twelve months increased the risk. Sounds strange right? In their discussion, the authors hypothesize that the greater risk in those breastfed past 12 months may have more to do with gluten than with breast milk. When a child is breastfed longer, the introduction of gluten may be later, after six months of age. Furthermore, since the child is older at gluten introduction, he may be exposed to larger amounts. The authors also mention that some mothers may have nursed longer due to perceived food sensitivities.
In the end, what is the take away from this study, and others, looking at infant feeding and the development of Celiac? It seems that there may be a window for gluten introduction between 5-6 months. Introduction before and after this time seem to increase the risk of Celiac. As far as breastfeeding, most studies point toward a large protective effect.
The development of Celiac Disease seems to be a perfect storm of genetic and environmental factors. Factors that may be out of any one person’s control. Studies should continue to look at early infant feeding and disease development, but all data should also be interpreted knowing that as hard as we try, some times, some things just can’t be prevented.