Studies examining FOBT and ascorbic acid
| STUDY | STUDY POPULATION | STUDY GROUPS | DESIGN | RESULTS | COMMENTS |
|---|---|---|---|---|---|
| Jaffe et al (1975)55 | Case report In vitro stool testing | Iron deficiency anemia patient taking ascorbic acid (500 mg 4 times daily) | Case report, in vitro testing | Negative Hemoccult results reverted to positive when ascorbic acid was discontinued Ascorbic acid level of 15.4 mg/dL (0.15 mg/g wet-weight stool) completely inhibited Hemoccult reaction for lysed blood in stool | Unreported blood concentration in stool |
| Jaffe and Zierdt (1979)56 | Volunteer subjects (no further information given) | Swallowed 20 mL of autologous blood followed by increasing doses of ascorbic acid (N = 4) | Temporally controlled trial | Hemoccult results initially positive in all subjects Required 1500 mg/d of ascorbic acid for complete inhibition of Hemoccult reaction | Incomplete inhibition at lower doses |
| Zierdt and Zierdt (1985)57 | Hospitalized patients requiring FOBT | Patients taking ascorbic acid (1 patient taking 1 g/d, other doses not reported) (N = 4) | Cross-sectional | All patients had negative Hemoccult and ColoScreen results, but 2 had positive benzidine test results (including patient taking 1 g/d of ascorbic acid) | True and false positives not reported |
FOBT—fecal occult blood testing.