Did Crohn’s disease evolve with the advent of refrigerators?

Authors of a hypothesis article in this week’s issue of THE LANCET propose that the emergence of Crohn’s disease in the second half of the 20th century-the same time that domestic refrigerators became widely available-is no coincidence. The authors suggest that certain types of bacteria that can survive in refrigerated food may be implicated in Crohn’s disease.

Crohn’s disease is thought to be caused by environmental factors (diet, lifestyle, smoking) among genetically susceptible individuals. Mutations in CARD15, a gene involved in innate immunity, are known to predispose people to the disease.

Jean-Pierre Hugot from Hopital Robert Debre, Paris, France, and colleagues discuss the cold-chain hypothesis (the production and storage of food in low temperatures) as a potential major risk factor for Crohn’s disease. Jean-Pierre Hugot comments: “All findings point to refrigeration as a potential risk factor for Crohn’s disease. Furthermore, cold-chain development paralleled the outbreak of Crohn’s disease during the 20th century. The cold chain hypothesis suggests that psychrotrophic bacteria such as Yersinia and Listeria-commonly found in beef, pork, chicken, sausages, hamburgers, cheese, and lettuce-contribute to the disease. These bacteria have been identified in Crohn’s disease lesions. From a molecular perspective, we suggest that the disease is a result of a defect in host recognition by pathogenic bacterial components that usually escape the immune response, which results in an excessive host response to these bacteria.”