Vegetarian Dietary Patterns and the Risk of Colorectal Cancers

Abstract

IMPORTANCE Colorectal cancers are a leading cause of cancer mortality, and their primary prevention by diet is highly desirable. The relationship of vegetarian dietary patterns to colorectal cancer risk is not well established.OBJECTIVE To evaluate the association between vegetarian dietary patterns and incident colorectal cancers. DESIGN, SETTING, AND PARTICIPANTSThe Adventist Health Study 2 (AHS-2) is a large, prospective, North American cohort trial including 96 354 Seventh-Day Adventist men and women recruited between January 1, 2002, and December 31, 2007. Follow-up varied by state and was indicated by the cancer registry linkage dates. Of these participants, an analytic sample of 77 659 remained after exclusions. Analysis was conducted using Cox proportional hazards regression, controlling for important demographic and lifestyle confounders. The analysis was conducted between June 1, 2014, and October 20, 2014.EXPOSURES Diet was assessed at baseline by a validated quantitative food frequency questionnaire and categorized into 4 vegetarian dietary patterns (vegan, lacto-ovo vegetarian, pescovegetarian, and semivegetarian) and a nonvegetarian dietary pattern. MAIN OUTCOMES AND MEASURESThe relationship between dietary patterns and incident cancers of the colon and rectum; colorectal cancer cases were identified primarily by state cancer registry linkages.RESULTS During a mean follow-up of 7.3 years, 380 cases of colon cancer and 110 cases of rectal cancer were documented. The adjusted hazard ratios (HRs) in all vegetarians combined vs nonvegetarians were 0.78 (95% CI, 0.64-0.95) for all colorectal cancers, 0.81 (95% CI, 0.65-1.00) for colon cancer, and 0.71 (95% CI, 0.47-1.06) for rectal cancer. The adjusted HR for colorectal cancer in vegans was 0.84 (95% CI, 0.59-1.19); in lacto-ovo vegetarians, 0.82 (95% CI, 0.65-1.02); in pescovegetarians, 0.57 (95% CI, 0.40-0.82); and in semivegetarians, 0.92 (95% CI, 0.62-1.37) compared with nonvegetarians. Effect estimates were similar for men and women and for black and nonblack individuals.CONCLUSIONS AND RELEVANCE Vegetarian diets are associated with an overall lower incidence of colorectal cancers. Pescovegetarians in particular have a much lower risk compared with nonvegetarians. If such associations are causal, they may be important for primary prevention of colorectal cancers.

Physical Activity and Nutrition in Primary and Tertiary Prevention of Colorectal Cancer

“…stop drinking alcohol and smoking, trying to optimize their weight, starting regular moderate exercise, and changing their eating habits with meals mainly containing fruit, vegetables, poultry, and fish (so-called ‘Mediterranean' diet). A recent study showed that a pescovegetarian diet (vegetarians who also consume fish and seafood) reduced the risk by 43% [40]. …”

Total Diet Approach to Cancer Prevention: A Narrative Review of the Literature Since 2011 Concerning the Association of Colorectal Cancer and Meat Consumption

“…Several studies have identified dietary patterns to investigate the association of the total diet on CRC risk. While the study designs, methods, participant populations, and derived dietary patterns differ, the three reviews [33][34][35], three case-control [36][37], and two prospective cohort studies [38][39][40] all concluded that meat-based diets are associated with an increased risk of CRC and that plant-based diets, rich in fruit, vegetables, and low in red and processed meat, may reduce CRC risk. These findings are consistent with Tantamango-Bartley et al [41] who found that vegetarian versus non-vegetarian dietary patterns were associated with significantly reduced cancer incidence (HR 0.92, 95% CI 0.85-0.99).…”

Prevention: Tending the gut

“…One recent study drives the point home. In a population of more than 77,000 people who refrained from smoking and drinking, those who ate fish but no other meat seemed to cut their risk of colorectal cancer nearly in half 5 . Obesity and physical inactivity also "We saw that 80% of colon cancer was really looking preventable."…”