Randomized controlled trials and meta-analysis of FOBT results with diet manipulation
| STUDY | N | POPULATION | FOBT TEST | INTERVENTION | REHYDRATION STATUS | DELAY TO DEVELOPMENT | RESULTS | COMMENTS |
|---|---|---|---|---|---|---|---|---|
| Hoogewerf et al,29 1987 | 3554 | BC residents ≥ 45 y presenting to FP with no GI symptoms or history | Hemoccult II | Unrestricted diet vs no red meat | NC | NC | 2.1% positive for restricted diet; 2.2% positive for unrestricted diet (NS) | False-positive rates were not evaluated |
| Joseph30 1988 | 639 | Patients of the medical clinic of the Minneapolis Veterans Administration with outpatient FOBTs ordered by resident | Hemoccult II | Unrestricted diet vs low-peroxidase diet* beginning 48 hours before testing | Nonrehydrated | NC | 5.4% positive for restricted diet; 5.6%† positive for unrestricted diet (NS) | Colonoscopy in 69% of patients with positive results showed false-positive rates for CRC or villous or adenomatous polyps in 2.2% on restricted diet and 2.5% on unrestricted diet |
| Verne et al,31 1993 | 311 | General practice patients in Thame, England, 40–74 y, without CRC symptoms or history | Hemoccult | Unrestricted diet vs low-peroxidase* diet beginning 2 d before testing | NC | NC | 5.8% positive for restricted diet; 2.2%† positive for unrestricted diet (NS) | False-positive rates were not evaluated |
| Robinson et al,32 1994 | 95 | Participants in the Nottingham trial, 50–74 y, excluding those with cancer or serious health problems | Hemoccult | Unrestricted diet vs low-peroxidase* diet beginning 2 d before testing | NC | NC | 7.7% positive for restricted diet; 5.4% for unrestricted diet | All 6 patients with positive results had colonoscopies: 1 had CRC; 1 had a 1.7-cm adenoma (other group NC) |
| Pignone et al,3 2001 | 4599 | Participants in 4 RCTs21–24 | Hemoccult, Hemoccult II | Unrestricted diet vs low-peroxidase* diet | Nonrehydrated or NC | NC | No difference in rates of positive results between unrestricted and restricted diets | None |
CRC—colorectal cancer, FOBT—fecal occult blood test, GI—gastrointestinal, NC—not clarified in publication, NS—No statistically significant difference between groups, RCT—randomized controlled trial.
↵* Low peroxidase diet involves eating no red meats and no high-peroxidase fruits or vegetables (horseradish, turnip, melon, etc).
↵† Incorrectly reported in original article.