Breastfeeding, Gluten Introduction, and Risk of Celiac Disease

A study published yesterday in the journal Pediatrics suggests that later introduction of gluten and breastfeeding beyond 12 months both increase the risk of a child developing celiac disease. These new findings add to the already muddy waters of our current understanding of the role of infant feeding in celiac disease.

Photo by Shree Krishna Dhital, via Wikimedia Commons

Celiac disease is an immune response to gluten, a protein found in wheat, barley, and rye. Celiac is characterized by inflammation and damage to the small intestine, leading to symptoms such as diarrhea and digestive pain. In the U.S., celiac disease is present in about 1 in 141 people, although many of these cases go undiagnosed. Infants that develop celiac disease often have poor growth or weight loss, because intestinal damage compromises nutrient absorption. They also may have chronic diarrhea and a swollen, painful belly.

Celiac can usually be treated with a gluten-free diet, but there isn’t a cure for the disease. Multiple genetic markers have been identified for celiac disease, but many genetically susceptible individuals tolerate gluten and never develop symptoms, leading to speculation about other risk factors, including early childhood nutrition.

This latest study was a large, prospective survey of infant feeding practices and development of celiac disease in Norwegian children. Parents were asked when they first introduced gluten and how long they breastfed their babies. Children that developed celiac disease were tracked through Norway’s national medical system. The study included 324 children with diagnosed celiac disease and 81,843 without celiac. The researchers then looked for patterns in the data that might help to explain why some children developed celiac disease and others did not.

There were two major findings to emerge from this study:

  1. Children that had not yet tried gluten by 6 months of age were more likely to develop celiac disease.
  2. Breastfeeding at the time of introduction to gluten did NOT appear to be protective. In fact, breastfeeding for longer than 12 months was associated with an increased risk, although it was borderline significant (P=0.046).

Both of these findings are contradictory to current infant feeding advice in the U.S. The AAP’s Section on Breastfeeding recommends exclusive breastfeeding for about 6 months before introducing solid foods, followed by “continuation of breastfeeding for 1 year or longer as mutually desired by mother and infant.” The same AAP policy goes on to say, “There is a reduction of 52% in the risk of developing celiac disease in infants who were breastfed at the time of gluten exposure.” But this Norwegian study effectively found that following the current advice of the AAP seems to increase a baby’s risk of celiac, not decrease it.

Obviously, we need more information here. And as usual, one study isn’t enough to give us the full picture of what we know and don’t know about this topic.

To understand the evolving hypotheses around celiac disease and infant feeding, we need to go back to Sweden in the mid-1980’s, when the rates of celiac disease in young kids suddenly quadrupled from an incidence of 1 in 1000 births to 4 in 1000 births over just a few years. It was an epidemic, and it appeared to be isolated to Sweden; neighboring countries weren’t affected. What’s more, celiac was showing up in really young kids. The median age of diagnosis during the epidemic was just about a year old. In 1995, celiac disease in Sweden plummeted back to pre-epidemic levels, and the median age of diagnosis increased to 4 years of age. Continue reading

Why Care About Breastfeeding Research?

Since becoming a mom, and especially since starting this blog, I have paid particular attention to new breastfeeding research. After all, my training is in nutrition, and breast milk is one of the most interesting foods around. Plus, I’m currently lactating and still breastfeeding my daughter a few times per day, so it’s on my mind.

When I look back at the papers that I have covered and those that I find on other blogs and media outlets, I notice that many focus on how breastfeeding improves outcomes in babies.

But I also notice that when I blog about breastfeeding research, I have to spend a big chunk of the piece talking about the limitations of the study. Breastfeeding research – at least when conducted in humans – will always have big limitations that require disclaiming and explaining. The problem is that it is impossible to randomize breastfeeding trials or to “blind” the subjects to feeding type. It is difficult to know, despite the fanciest statistical methods, if it is breast milk that makes those babies thinner, smarter, stronger, cry more, etc, or if there are other factors at play in this complex thing called human life. Sometimes, by the time I’ve listed the problems with interpreting a breastfeeding study, I wonder if these findings were actually meaningful, and I’m sure my readers feel the same way.

Elsewhere around the Internet (not so much on my blog), I often see comments to this effect on articles about the latest research on the benefits of breastfeeding:

“Another useless study. Obviously we mammals were meant to feed our babies breast milk. I don’t know why scientists waste their time and our money with this stuff.”

Why bother doing more research on outcomes associated with breastfeeding? It is pretty clear that breastfeeding is a great way to feed an infant. Maybe it is time to stop oohing and awing over breast milk. Continue reading

Bottle-feeding and Obesity Risk

Source: Wikimedia Commons

A study published this month in Archives of Pediatric and Adolescent Medicine looks at the relationship between infant feeding practices and weight gain (1). Breast milk vs. formula? Nope, it isn’t that simple.

Led by Dr. Ruowei Li of the CDC, this prospective longitudinal study tracked feeding and weight gain in 1900 infants during their first year of life. Each month, mothers were asked how they fed their babies in the last 7 days, and from their replies, infants were grouped into the following categories across ages:

  1. Breastfed only
  2. Breastfed and human milk by bottle
  3. Breastfed and formula by bottle
  4. Human milk by bottle only (i.e. exclusive pumping)
  5. Human milk and formula by bottle
  6. Formula by bottle only

The mothers in this study were mainly white, married, and had at least a high school education. A third were on WIC. About 50% were overweight or obese. Statistical methods were used to adjust the findings for a range of maternal factors, including BMI, as well as infant sex, gestational age, birth weight, and age of solid food introduction.

The most important finding from this study was that infants fed by bottle only – whether fed formula or breast milk – gained more weight than those fed breast milk at the breast. Continue reading