The mechanism research of the effect of high fat and abnormal metabalism of intestinal microflora on the risk of colorectal cancer

Interventions: diet intervention:reduce calorie intake;probiotics intervention:take probiotics;combined intervention:reduce calorie intake&take probiotics;no intervention:nothing
Primary outcome(s): detection of intestinal flora;detection of blood;incidence of colorectal cancer
Study Design: Randomized parallel controlled trial