title: Folic acid prevents the initial occurrence of sporadic colorectal adenoma in Chinese older than 50 years of age: a randomized clinical trial.
abstract: Colorectal adenoma (CRA) is the precursor lesion of colorectal cancer (CRC). Several agents have been shown to be effective in the chemoprevention of CRA recurrence, but there has been little research on its primary prevention. Participants older than 50 years with no adenomas were recruited for our study and randomized to receive either 1 mg/day folic acid supplement or treatment without folic acid. After 3 years of follow-up, plasma folate and colonoscopy were evaluated. Seven hundred ninety-one participants (91.98%) completed the study. CRA occurred in 64 (14.88%) participants in the folic acid group and 132 (30.70%) in the control group [unadjusted risk ratio (RR), 0.49; 95% confidence interval (CI), 0.37-0.63; P < 0.01]; left-sided adenoma (unadjusted RR, 0.54; 95% CI, 0.38-0.76; P = 0.001) and advanced CRA (unadjusted RR, 0.36; 95% CI, 0.16-0.81; P = 0.01) were most common. There was no significance difference in the occurrence of three or more adenomas (unadjusted RR, 0.70; 95% CI, 0.36-1.77; P = 0.38) or right-sided adenoma (unadjusted RR, 0.55; 95% CI, 0.30-1.00; P = 0.07) between the two groups. Participants with low plasma folate may have a high risk of CRA. In conclusion, primary prevention with 1 mg/day folic acid supplementation could reduce the incidence of CRA, especially left-sided and advanced disease in those with no previous adenomas. People with differing baseline plasma folate levels should be given individualized treatment. Those with low plasma folate should be encouraged to take adequate supplements; plasma folate should be elevated to an effective therapeutic level, which may reduce the incidence of CRA.
authors.affiliation: Division of Gastroenterology and Hepatology, Ren-Ji Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China.
authors.forename: Qin-Yan
authors.initials: QY
authors.lastname: Gao
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Chen
authors.forename: Ying-Xuan
authors.initials: YX
authors.lastname: Chen
authors.forename: Ying-Chao
authors.initials: YC
authors.lastname: Wang
authors.forename: Zheng-Hua
authors.initials: ZH
authors.lastname: Wang
authors.forename: Jie-Ting
authors.initials: JT
authors.lastname: Tang
authors.forename: Zhi-Zheng
authors.initials: ZZ
authors.lastname: Ge
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Chen
authors.forename: Jian-Qiu
authors.initials: JQ
authors.lastname: Sheng
authors.forename: Dian-Chun
authors.initials: DC
authors.lastname: Fang
authors.forename: Cheng-Gong
authors.initials: CG
authors.lastname: Yu
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.forename: Jing-Yuan
authors.initials: JY
authors.lastname: Fang
mesh_terms: D000236:Adenoma / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D016022:Case-Control Studies; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use*; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000517:prevention & control*; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D014803:Vitamin B Complex / Q000627:therapeutic use*
chemical_list: D014803:Vitamin B Complex; D005492:Folic Acid