Men who consume higher quantities of red meat are at an increased risk of developing diverticulitis, especially if they’re eating unprocessed red meat, according to a new study published in Gut.
“In our prior analysis from a large prospective cohort study, the Health Professionals Follow-Up Study (HPFS), we found that red meat intake, independent of fiber, may be associated with a composite outcome of symptomatic diverticular disease, which included 385 incident cases over 4 years of follow-up,” wrote the authors, led by Andrew T. Chan, MD , of Massachusetts General Hospital, Boston. Dr. Chan added that “in the present study, we updated this analysis, which allowed us to prospectively examine the association between consumption of meat (total red meat, red unprocessed meat, red processed meat, poultry, and fish) with risk of incident diverticulitis in 764 cases over 26 years of follow-up.”
Dr. Chan and his coinvestigators conducted a prospective cohort study using subjects from the ongoing HPFS. Men who already had a diagnosis of diverticulitis, associated complications, inflammatory bowel disease, or a GI-related cancer at baseline were excluded from this analysis, leaving 46,461 eligible subjects. Of those, 764 developed diverticulitis.
Subjects in the HPFS responded to questionnaires regarding their dietary habits, with questions specifically asking if they consumed red meat and/or unprocessed red meat and at what frequency. Nine responses to each question were possible, with the lowest being “never or less than once per month” to “six or more times per day.” These questionnaires were sent out every 2 years during the follow-up period, with more extensive follow-ups – at which investigators would monitor medical history, disease outcomes, and so on – occurring every 4 years during the follow-up period. Red meat consumption was divided in quintiles of 1-5, with 1 being the lowest amount and 5 and being the highest.
The entirety of the follow-up period constituted 651,970 person-years. Average servings of total red meat per week were 1.2 in quintile 1, compared to 5.3 in quintile 3 and 13.5 in quintile 5. Those in the highest quintile had a multivariable risk ratio of 1.58 (95% CI, 1.19-2.11; P = .01), indicating a significantly higher risk for developing diverticulitis. In terms of unprocessed red meat, the average number of servings per week were 0.8 for the lower quintile, 3.2 for quintile 3, and 8.6 for quintile 5, yielding a risk ratio of 1.51 (95% CI, 1.12-2.03, P = .03) when comparing the highest and lowest cohorts. The increase in risk, however, leveled off after about 6 servings of red meat per week, and was found to be nonlinear (P = .002). Those who ate more servings of poultry or fish did not have a higher risk of diverticulitis.
“We also observed that unprocessed red meat, but not processed red meat, was the primary driver for the association between total red meat and risk of diverticulitis,” the authors explained. “Compared with processed meat, unprocessed meat (e.g., steak) is usually consumed in larger portions, which could lead to a larger undigested piece in the large bowel and induce different changes in colonic microbiota [and] higher cooking temperatures used in the preparation of unprocessed meat may influence bacterial composition or proinflammatory mediators in the colon.”
Although medical information and self-reports were validated, there are inherent possible limitations to self-reported data, such as misremembering the amount of meat consumed or reporting incorrect amounts. Residual confounding may have occurred despite adjustment of the data to account for it.
The National Institutes of Health funded the study. The authors reported no conflicts of interest.