Reference Study name Country Study design Follow‐up Funding	Original cohort (N total) Exclusion criteria Study population	Ascertainment of outcome	Exposure groups n/person‐years Exposure assessment method	Incident cases	Model covariates	Results
Martínez et al. (2004) WBF US RCT analysed as PC 3 yrs Mixed	N = 1429 Population sampled: 40–80 yrs who had had ≥1 colorectal adenoma measuring ≥3 mm removed at colonoscopy within 3 months before study entry were recruited Exclusion criteria: subjects with a personal history of inflammatory bowel disease or hereditary colon cancer syndromes as well as those with more than one first‐degree family member with CRC % lost to follow‐up: 8.8% N = 1014 Sex (% women): 30% Age (mean ± SD): 65,275 ± 8.95	Data on adenoma characteristics (i.e. number, size, location, histology) were obtained from medical records and pathology reports as previously reported FFQ was used for the dietary intake and plasma folate was analysed by using the Bio‐Rad Quantaphase II Radioassay	Unit of measurement Plasma folate (nmol/L) Q1: <5.02 Q2: 5.02–8.19 Q3: 8.20–12.75 Q4: >12.75 Total folate intake (μg/d), mean: Q1: <275 Q2: 275–414 Q3: 415–664 Q4: >664 Energy‐adjusted: no	Incident recurrence/ without recurrence Q1: 133/254 Q2: 115/254 Q3: 128/253 Q4: 119/253 Dietary folate: Q1: 121/254 Q2: 129/253 Q3: 124/254 Q4: 121/253 Total folate intake: Q1: 137/254 Q2: 126/253 Q3: 119/254 Q4: 113/253	Adjusted for age, sex, number of colonoscopies, history of polyps before baseline examination.	OR (95% CI) Plasma folate vs. adenoma recurrence Q1 (ref): 1.00 Q2: 0.61 (0.42, 0.89) Q3: 0.79 (0.54, 1.15) Q4: 0.66 (0.46, 0.97) p for trend: 0.04 Total folate intake vs. adenoma recurrence Q1 (ref): 1.00 Q2: 0.75 (0.52, 1.09) Q3: 0.71 (0.48, 1.03) Q4: 0.61 (0.42, 0.89) p for trend: 0.01

Abbreviations: CI, Confidence Interval; CRC, Colorectal Cancer; OR, Odds ratio; PC, Prospective cohort; RCT, Randomised controlled trial; SD, Standard deviation; WBF, Wheat Bran Fibre Trial; yrs, Years.