A diet rich in fibre and whole grains could influence the risk of developing colorectal cancer linked to a strain of gut bacteria called Fusobacterium nucleatum.
Fusobacterium nucleatum is an inflammatory bacterium that is thought to play a role in colorectal cancer by blocking the immune response triggered to combat tumour cells in the colon.
By studying the diets of 137,217 people over approximately 30 years, and analysing 1,000 samples from colorectal tumours and their Fusobacterium nucleatum levels, research by Doctor Raaj Mehta and colleagues from Harvard Medical School suggests that found that individuals eating diets rich in whole-grain cereals and fibre had a lower risk of developing colorectal cancer containing this particular type of bacteria.
However, the behaviour of tumours not containing Fusobacterium nucleatum was unchanged and the risk of developing colorectal cancer not containing the bacterium was not reduced.
The study concludes that, beyond this type of bacteria, dietary choices have the potential to increase or reduce cancer risk by affecting the bacteria in the digestive tract.
Colorectal cancer is the second most deadly form of cancer and the third most common form of the disease. However, if detected early, colorectal cancer can be cured in nine out of 10 cases.
Abstract
Importance: Fusobacterium nucleatum appears to play a role in colorectal carcinogenesis through suppression of the hosts’ immune response to tumor. Evidence also suggests that diet influences intestinal F nucleatum. However, the role of F nucleatum in mediating the relationship between diet and the risk of colorectal cancer is unknown.
Objective: To test the hypothesis that the associations of prudent diets (rich in whole grains and dietary fiber) and Western diets (rich in red and processed meat, refined grains, and desserts) with colorectal cancer risk may differ according to the presence of F nucleatum in tumor tissue.
Design, Setting, and Participants: A prospective cohort study was conducted using data from the Nurses’ Health Study (June 1, 1980, to June 1, 2012) and the Health Professionals Follow-up Study (June 1, 1986, to June 1, 2012) on a total of 121 700 US female nurses and 51 529 US male health professionals aged 30 to 55 years and 40 to 75 years, respectively (both predominantly white individuals), at enrollment. Data analysis was performed from March 15, 2015, to August 10, 2016.
Exposures: Prudent and Western diets.
Main Outcomes and Measures: Incidence of colorectal carcinoma subclassified by F nucleatum status in tumor tissue, determined by quantitative polymerase chain reaction.
Results Of the 173 229 individuals considered for the study, 137 217 were included in the analysis, 47 449 were male (34.6%), and mean (SD) baseline age for men was 54.0 (9.8) years and for women, 46.3 (7.2) years. A total of 1019 incident colon and rectal cancer cases with available F nucleatum data were documented over 26 to 32 years of follow-up, encompassing 3 643 562 person-years. The association of prudent diet with colorectal cancer significantly differed by tissue F nucleatum status (P = .01 for heterogeneity); prudent diet score was associated with a lower risk of F nucleatum–positive cancers (P = .003 for trend; multivariable hazard ratio of 0.43; 95% CI, 0.25-0.72, for the highest vs the lowest prudent score quartile) but not with F nucleatum–negative cancers (P = .47 for trend, the corresponding multivariable hazard ratio of 0.95; 95% CI, 0.77-1.17). There was no significant heterogeneity between the subgroups in relation to Western dietary pattern scores.
Conclusions and Relevance: Prudent diets rich in whole grains and dietary fiber are associated with a lower risk for F nucleatum–positive colorectal cancer but not F nucleatum–negative cancer, supporting a potential role for intestinal microbiota in mediating the association between diet and colorectal neoplasms.
Authors
Raaj S Mehta; Reiko Nishihara; Yin Cao; Mingyang Song; Kosuke Mima; Zhi Rong Qian; Jonathan A Nowak; Keisuke Kosumi; Tsuyoshi Hamada; Yohei Masugi; Susan Bullman; David A Drew; Aleksandar D Kostic; Teresa T Fung; Wendy S Garrett; Curtis Huttenhower; Kana Wu; Jeffrey A. Meyerhardt; Xuehong Zhang; Walter C Willett; Edward L Giovannucci; Charles S Fuchs; Andrew T Chan; Shuji Ogino
[link url="https://www.yahoo.com/news/fiber-rich-diet-could-cut-colorectal-cancer-risk-131654632.html"]Yahoo News report[/link]
[link url="http://jamanetwork.com/journals/jamaoncology/article-abstract/2598745"]JAMA Oncology abstract[/link]