May 2011 Issue
A Rarity No More — Science Seeks a Cause for Rise in Celiac Disease Occurrence
By Sharon Palmer, RD
Vol. 13 No. 5 P. 8
Gluten free is on everyone’s radar. Eight years ago, when the news broke that one in 133 people—an occurrence rate much higher than scientists had suspected—has celiac disease (CD), the term entered into the public vernacular. And gluten-free living became more amenable, thanks to a growing variety of gluten-free products and resources that became available, even though scientists understood little about the disease’s cause.
Enter the gluten-free diet craze. Today, gluten-free dieting has taken on a life of its own as it enters into fad diet territory. The growing faction of people who avoid gluten without just cause list a litany of reasons—usually unsupported by science—why people shouldn’t eat it, including that gluten makes people “fat” and that it causes numerous health ailments. Yet a body of evidence links whole grain consumption in healthy people with health benefits such as a decreased risk of cardiovascular disease, metabolic syndrome, obesity, type 2 diabetes, colorectal cancer, and mortality.
“People are blaming everything under the sun on gluten,” says one of the country’s leading CD experts, Alessio Fasano, MD, a professor of pediatrics, medicine, and physiology at the University of Maryland School of Medicine, medical director of the Center for Celiac Research, and director of the Mucosal Biology Research Center. “On a daily basis, 60 million people buy gluten-free products, and they are not all celiac.”
According to the Nielson Company, sales of gluten-free products increased 74% from 2004 to 2009, with a projected growth of 15% to 25% per year to reach about $2.6 billion in sales by 2012. This kind of growth certainly can’t be attributed solely to the number of people who have medical reasons for avoiding gluten. Fasano reports that there are three groups of people who should avoid gluten as a medical necessity: an estimated 3 million Americans who have CD, about 300,000 people with a formal allergic reaction to wheat, and about 20 million who are sensitive to gluten.
The chatter from so many fad dieters proclaiming the dangers of gluten has simply added to the confusion surrounding one of today’s most important medical mysteries: Why are more people getting CD? Urban legends and rumors on the cause have circulated, ranging from a lack of wheat crop biodiversity to the notion that humans are not genetically adapted to consume grains. But has science moved forward to begin unlocking the true reason behind the rise in CD occurrence?
In 2003, Fasano’s research team undertook the largest epidemiological study in U.S. history, screening 13,000 people from 35 states for CD. In the end, the researchers discovered that CD, which was once considered rare, is actually a common autoimmune disease with similar rates of occurrence as reported in Europe. The rate of CD in the United States had increased more than 20-fold since 1989 to an overall rate of one in 133 people. The study, published in Archives of Internal Medicine in 2003, concluded that CD occurs frequently, not only in patients with gastrointestinal symptoms but also in first- and second-degree relatives and patients with numerous common disorders, even in the absence of gastrointestinal symptoms. In addition, the disease was commonly neglected by the medical community.
“We only had one thought about the reason behind the rise in celiac disease,” says Fasano. “We thought it was simply increased awareness. Studies showed that it was much more frequent than suspected, and we were under the impression that was it.”
Fasano explains that scientists believed the development of CD was simply an interaction of gluten with genes. Once gluten had been introduced in baby food, an autoimmune reaction would immediately occur, while symptoms such as anemia, fatigue, skin rash, short stature, bloating, gas, and diarrhea might develop right away or later in life.
New Study on Occurrence Is a Game Changer
Assumptions changed when the results from Fasano’s 2010 study on the natural history of CD were published in the Annals of Medicine. His research team tested matched blood samples for CD autoimmunity in 3,511 subjects in the 1974 CLUE I and 1989 CLUE II cohorts. Thus, the study investigated the same group of individuals at two different times, 15 years apart. CD prevalence had increased twofold in the CLUE cohort and fivefold overall in the United States from 1974 to 1989. And here’s the kicker: The increase observed in the CLUE cohort was due to an increasing number of subjects who lost their immunological tolerance to gluten in their adulthood. By looking at the same group of people in 1974 and again in 1989, the researchers were able to demonstrate that loss of gluten tolerance can occur at any time in life. There were specific cases in which subjects who tested negative for CD in their early 50s tested positive for it in their late 60s.
These study results completely surprised Fasano; they were not the expected outcome when he designed the study.
“This study went against conventional wisdom. You are definitely born with the genes that predispose you to CD, but it depends on factors other than exposure to gluten,” says Fasano, who raises many interesting questions posed by the study. “How can people tolerate gluten for 30 to 50 years and then become intolerant? What made them lose their tolerance? Can we learn the tricks so that we can prevent celiac disease?”
Potential Factors in CD Development
So what are the factors that might spur the development of CD later in life? Fasano believes there are environmental factors involved, in particular gut bacteria, the so-called microbiota. “If you follow neonates from birth with high risk for CD that lose their gluten tolerance and develop CD—when you look at the composition of the bacteria in their guts, there are several different factors that suggest microbiota is involved,” he explains.
When it comes to theories such as a change of wheat crops or increased consumption of wheat products behind the rise in CD, Fasano doesn’t buy them; there has not been a dramatic change in these factors over the past 50 years that would adequately explain the rise in occurrence. There may be other factors at play, such as increased exposure to toxins, overuse of antibiotics, and vaccine exposure.
Fasano sees potential in promoting healthy gut microbiota. He reports that there will be future research looking into this area, adding, “I would not be shocked if we end up preventing CD with probiotics.”
— Sharon Palmer, RD, is a contributing editor at Today’s Dietitian and a freelance food and nutrition writer based in southern California.