Why does taking more than 250 mgs or vitamin C daily cause false positives on guaiac fecal occult blood tests?

It shouldntWhy does taking more than 250 mgs or vitamin C daily cause false positives on guaiac fecal occult blood tests?
Actually, Vitamin C often results in Flase NEGATIVES on the test.Why does taking more than 250 mgs or vitamin C daily cause false positives on guaiac fecal occult blood tests?
The body can only utilize so much of the vitamin, the rest is discarded and will show up in excreta and the urine... 250 mg. is more than the body can assimilate... at one time. Is why it is always recommended to take 100 mg tid.