Study results suggest that high meat intake increases IBD risk, and this association varies by the type of meat consumed.
Meat has been taking it on the chin for a couple of months now. First came the very widely covered news that the The International Agency for Research on Cancer, the cancer agency of the World Health Organization (WHO), has officially classified processed and red meat products like bacon and salami “carcinogenic to humans.” Now comes word from the Turkish Journal of Gastroenterology that meat consumption may contribute to inflammatory bowel disease (IBD) as well.
Much earlier research has been devoted to the potential causal relationship between meat and IBD, though the clinical evidence is pretty evenly split. Some studies have suggested a connection, and still others have suggested that the type of meat (along with how the meat is cooked) may play a role. Any established connection between meat and IBD would be clinically important, because the worldwide incidence of IBG continues to rise. Genetic and environmental causes are clearly implicated in that rise, but so, too, are smoking, drinking, and diet.
The review examined relevant studies from PubMed and EMBASE published between 1966 and July 2015. Red meat was defined as darker-colored meat from mammals, such as cows, lambs, pigs, and horses. White meat was defined as lighter-colored meat from poultry, such as chickens, and rabbits. The term “processed meat” referred to bacon, poultry sausage, luncheon meats (red and white meat), ham, and hot dogs.
Two cohort and seven case—control studies were included. The nine studies reported a total of 2,019 cases of ulcerative colitis (UC), 683 of Chron’s Disease (CD), and 160 of IBD. Of the nine studies, five examined total meat consumption, three only examined red meat consumption, two examined processed meat consumption, and two only examined white meat consumption.
Only red meat consumption was associated with IBD risk (RR: 2.37, 95% CI: 1.40—3.99). No significant association between white meat (RR: 1.20, 95% CI: 0.73–1.97) or processed meat (RR: 1.60, 95% CI: 0.53–4.78) and IBD risk was found. A significant association between total meat intake and UC risk was found (summary RR: 1.47; 95% CI: 1.01–2.15), whereas no association was detected between total meat intake and
CD risk (summary RR: 1.50, 95% CI: 0.98—2.28).
“The results suggest that high meat intake increases IBD risk, and this association varies by the type of meat consumed,” the reviewers observed. “Summary associations for red meat consumption are slightly greater compared with processed meat and white meat consumption. Several possible underlying mechanisms exist linking the consumption of meat, particularly red meat, and the incidence of IBD.”
Among the factors that may contribute to meat causing IBD are cooking meat at high temperatures, which creates chemical by-products with mutagenic or carcinogenic properties that may influence the digestive tract once ingested.
Limitations include that not all studies analyzed categorized meat consumption on the basis of amount consumed, whereas others did not specify consumption levels. Consequently, dose-response analysis was not possible. Other studies didn’t analyze the type of meat consumed. “Further cohort studies are warranted to confirm this association,” the authors concluded.