Got Crohn’s? Maybe the Fridge is to Blame
THURSDAY, Dec. 11 (HealthDayNews) — Could the modern-day obsession with appliances — namely refrigerators — be responsible for the emergence of Crohn’s disease, an inflammatory bowel condition?
Researchers writing in the Dec. 13 issue of The Lancet hypothesize that the emergence of Crohn’s at the same time Kelvinators and Amanas became fixtures in kitchens around the world is no mere coincidence.
In fact, that’s exactly how Dr. Jean-Pierre Hugot, lead author of the paper, describes his theory in an e-mail from Paris: That Crohn’s “is linked with our modern Occidental way of life, diet, bacteria and domestic hygiene.” Moreover, he adds,” all these findings are compatible with the refrigeration.”
Other researchers are taking a more cautious approach.
“It’s a plausible hypothesis, but there’s quite a bit of conjecture and it needs a cautious interpretation,” says Dr. Balfour Sartor, a professor of medicine, microbiology and immunology at the University of North Carolina.
Crohn’s disease, which is characterized by recurring inflammation of the small intestine, appears to be caused by a complicated interplay of genetic and environmental factors. And its prevalence grew in the second half of the 20th century.
“It is true that environmental factors interact with genetic susceptibility to cause the disease. Now the big question is, what is the environmental factor or factors?” asks Sartor.
The disease is believed to be an immune-mediated disease, meaning the body’s immune reaction goes awry in response to some outside stimulus.
A number of hypotheses have been put forth over the years, blaming, among other things, corn flakes cereals and, later, the refined sugar in corn flakes. A current popular theory, the “hygiene hypothesis,” posits that because children are no longer exposed to as much dirt or germs (due to the modern hygienic lifestyle), their immune systems are more vulnerable to pathogens.
“[The Lancet paper] is potentially a partial extension of the hygiene hypothesis, which has received a lot of attention in the last couple of years,” says Dr. Lloyd Mayer, chief of gastroenterology and chairman of the Immunobiology Center at Mount Sinai School of Medicine in New York City.
The theory also fits together a little too neatly for Mayer, who’s more than a bit skeptical.
The authors of The Lancet piece point not just to domestic refrigeration but to the whole “cold chain,” which apparently includes different ways of storing foods at low temperatures.
The idea is that specific bacteria that are able to survive in these chilly conditions cause the predisposed person’s immune system to overreact.
“Bacteria able to survive and develop in refrigerators are called psychrotrophic,” Hugot explains. “In the context of Crohn’s disease, they are mainly represented by Listeria and Yersinia species.”
Both of these species have been reported in Crohn’s disease lesions, Hugot adds. “Thus, there is a clear overlap between psychrotrophic bacteria and bacteria found in CD [Crohn's disease] lesions,” he adds. “This is certainly a very important point supporting our hypothesis.”
Hugot cautions, however, that this is still just a theory. “It is very important to consider this work only as a basis for additional research,” he says. “This theory is mainly speculative and needs to be proven or discarded and it cannot be retained today as a demonstration.”
Preliminary or not, the theory hasn’t convinced everyone.
Mayer notes Crohn’s may have existed long before the advent of home refrigerators, but health officials had yet to identify the disease. “Part of it was just lack of knowledge and lack of nomenclature,” Mayer says.
Also, the theory doesn’t take into account the complexity of the disease.
“You can correlate very nicely things that go in tandem, but there isn’t just one thing going on,” Mayer adds. “Refrigeration occurred, heating occurred, enclosed schools occurred, a whole host of things occurred. To make a [one-on-one] association is taking huge leaps of faith, and that’s been the problem with most of these types of studies.”
Adds Sartor: “The problem is that there are many other environmental factors that came along right at the same time — smoking, use of aspirin, food additives, public health measures in general, clearance of worms. All of these have been suggested by other investigators, and [there is] some data to support all of these theories. There is a lot of suggestive evidence, [but] it doesn’t say ‘slam-dunk-yes, that’s true.’”
More information
To learn more about Crohn’s disease, visit the Crohn’s & Colitis Foundation of America and the National Institutes of Health.
SOURCES: Jean-Pierre Hugot, M.D., Ph.D., service de gastroenterologie, Hopital Robert Debre, Paris, France; Lloyd Mayer, M.D, chief, gastroenterology, and chairman, Immunobiology Center, Mount Sinai School of Medicine, New York City; Balfour Sartor, M.D., professor of medicine, microbiology and immunology, University of North Carolina at Chapel Hill; Dec. 13, 2003, The Lancet~CROH~