Science Daily — According to new research presented at Digestive Disease Week 2007 a vegetarian diet may have a significant impact on the gastrointestinal system, affecting the risk for certain diseases.
The average person's lifetime risk of developing colorectal cancer (CRC) is about seven percent and the role of diet in preventing this type of cancer remains under debate. Most of all, previous studies enrolled middle-aged subjects, raising the possibility that CRC development may start before common interventions. Researchers from Tata Memorial Hospital (TMH) in Mumbai, India, set out to determine whether a vegetarian diet is associated with reduced risk of CRC if started very early in life.
In this study, researchers used a prospectively created database of 8,877 Indian patients managed in a clinical nutrition service from January 1, 2000 through December 31, 2005, to examine the association of life-long vegetarianism with incidence of CRC. During the evaluation for nutrition support, a history of life-long vegetarianism (due to religious reasons) was obtained from all patients to plan an appropriate diet. Twenty-seven percent of subjects (2,092 patients) from the control cohort were life-long vegetarians and 22.4 percent (178 patients) of subjects with colon cancer were vegetarians.
Patients with colorectal cancer (n=796) comprised the primary patient cohort for this study. Three groups of controls were generated from the same database for separate comparison with the CRC cohort. These included all patients with non-CRC cancers (control group one: n=7,273), patients with non-CRC and tobacco-related cancers (control group two: n=1,844), and patients with benign disorders (control group three: n=74). Multivariate analysis of 7,641 patients was performed by adjusting for age, gender, body mass index and economic status.
Vegetarianism was significantly associated with patients over 65 years, male gender, body mass index (BMI) of less than 20 Kg/m2 and economic deprivation. Colorectal cancer was positively associated with old age and male gender, and inversely associated with vegetarian diet, low BMI and economic deprivation. The inverse association of CRC and lifelong vegetarianism was observed with all the three control groups.
"A well-planned vegetarian diet is a healthy way to meet your nutritional needs," said Yogesh M. Shastri, M.D., of Johann Wolfgang Goethe University Hospital, Frankfurt, Germany and previously a co-author of this study at TMH, Mumbai, India. "The exact mechanism by which life long vegetarianism may reduce the risk of sporadic CRC needs further investigation. Prolonged vegetarianism starting in early life may be a viable lifestyle option for those at risk of developing the disease."