Protection against certain cancers. Naturally occurring chemicals (indoles, isothiocyanates, glucosinolates, dithiolethiones, and phenols) in cauliflower, Brussels sprouts, broccoli, cabbage, and other cruciferous vegetables appear to reduce the risk of some cancers, perhaps by preventing the formation of carcinogens in your body or by blocking cancer-causing substances from reaching or reacting with sensitive body tissues or by inhibiting the transformation of healthy cells to malignant ones.

All cruciferous vegetables contain sulforaphane, a member of a family of chemicals known as isothiocyanates. In experiments with laboratory rats, sulforaphane appears to increase the body's production of phase-2 enzymes, naturally occurring substances that inactivate and help eliminate carcinogens. At the Johns Hopkins University in Baltimore, Maryland, 69 percent of the rats injected with a chemical known to cause mammary cancer developed tumors vs. only 26 percent of the rats given the carcinogenic chemical plus sulforaphane.

In 1997, Johns Hopkins researchers discovered that broccoli seeds and three-day-old broccoli sprouts contain a compound converted to sulforaphane when the seed and sprout cells are crushed. Five grams of three-day-old broccoli sprouts contain as much sulforaphane as 150 grams of mature broccoli. The sulforaphane levels in other cruciferous vegetables have not yet been calculated.

Adverse Effects Associated with Cauliflower

Enlarged thyroid gland (goiter). Cruciferous vegetables, including cauliflower, contain goitrin, thiocyanate, and isothiocyanate. These chemicals, known collectively as goitrogens, inhibit the formation of thyroid hormones and cause the thyroid to enlarge in an attempt to produce more. Goitrogens are not hazardous for healthy people who eat moderate amounts of cruciferous vegetables, but they may pose problems for people who have a thyroid condition or are taking thyroid medication.

Intestinal gas. Bacteria that live naturally in the gut degrade the indigestible carbohydrates (food fiber) in cauliflower, producing intestinal gas that some people find distressing.

Food/Drug Interactions

Anticoagulants. Cauliflower contains vitamin K, the blood-clotting vitamin produced naturally by bacteria in our intestines. Additional intake of vitamin K may reduce the effectiveness of anticoagulants (warfarin, Coumadin, Panwarfin), requiring larger-than-normal doses to produce the same effect.

False-positive test for occult blood in the stool. The active ingredient in the guiac slide test for hidden blood in feces is alphaguaiaconic acid, a chemical that turns blue in the presence of blood. Cauliflower 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.