The New Complete Book of Food
known collectively as goitrogens, are not hazardous for healthy people who eat moderate
amounts of cruciferous vegetables, but they may pose problems for people who have thyroid
problems or are taking thyroid medication.
False-positive test for occult blood in the stool. The guaiac slide test for hidden blood in feces
relies on alphaguaiaconic acid, a chemical that turns blue in the presence of blood. Broccoli
contains peroxidase, a natural chemical that also turns alphaguaiaconic acid blue and may
produce a positive test in people who do not actually have blood in the stool.Food/Drug Interactions
Anticoagulants Broccoli is rich in vitamin K, the blood-clotting vitamin produced natu-
rally by bacteria in the intestines. Consuming large quantities of this food may reduce the
effectiveness of anticoagulants (blood thinners) such as warfarin (Coumadin). One cup
of drained, boiled broccoli contains 220 mcg vitamin K, nearly four times the R DA for a
healthy adult.