Protection against some cancers. Naturally occurring chemicals (indoles,
isothiocyanates. glucosinolates, dithiolethiones, and phenols) in
Brussels sprouts, broccoli, cabbage, cauliflower, and other
cruciferous vegetables appear to reduce the risk of some forms of
cancer, 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.
To get a
protective amount of sulforaphane from broccoli you would have to eat
about two pounds a week. But 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 sprouts contain as much
sulphoraphane as 150 grams of mature broccoli.
Lower
risk of some birth defects. Up to two or every 1,000 babies born
in the United States each year may have cleft palate or a neural tube
(spinal cord) defect due to their mothers' not having gotten adequate
amounts of folate during pregnancy. The current RDA for folate is 180
mcg for a woman, 200 mcg for a man, but the FDA now recommends 400 mcg
for a woman who is or may become pregnant. Taking a folate supplement
before becoming pregnant and continuing through the first two months
of pregnancy reduces the risk of cleft palate; taking folate through
the entire pregnancy reduces the risk of neural tube defects. Broccoli
is a good source of folate. One raw broccoli spear has 107 mcg folate,
more than 50 percent of the RDA for an adult.
Lower
risk of heart attack. In the spring of 1998, an analysis of data
from the records for more than 80,000 women enrolled in the
long-running Nurses Health Study at Harvard School of Public
Health/Brigham and Woman's Hospital in Boston demonstrated that a diet
providing more than 400 mcg folate and 3 mg vitamin B6 a
day from either food or supplements, more than twice the current RDA
for each, may reduce a woman's risk of heart attack by almost 50
percent. Although men were not included in the analysis, the results
are assumed to apply to them as well. NOTE: Fruit, green leafy
vegetables, beans, whole grains, meat, fish, poultry, and shellfish
are good sources of vitamin B6.
Enlarged thyroid gland. Cruciferous vegetables, including
broccoli, contain goitrin, thiocyanate, and isothiocyanate, chemical
compounds that inhibit the formation of thyroid hormones and cause the
thyroid to enlarge in an attempt to produce more. These chemicals,
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 guiac 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.