00 The New Complete Book of Food
How Other Kinds of Processing Affect This Food
Freezing. Crisp fruit and vegetables like apples, carrots, potatoes, turnips, and rutabagas
snap when you break or bite into them because their cells are so full of moisture that they
pop when the cell walls are broken. When these vegetables are cooked and frozen, the
water inside their cells turns into ice crystals that tear cell membranes so that the mois-
ture inside leaks out when the vegetable is defrosted and the cells collapse inward, which
is the reason defrosted turnips and rutabagas, like defrosted carrots and potatoes, have a
mushy texture.Medical Uses and/or Benefits
Lower risk of cancer. Naturally occurring chemicals (indoles, isothiocyanates, glucosino-
lates, dithiolethiones, and phenols) in cabbage, Brussels sprouts, broccoli, cauliflower, and
other cruciferous vegetables appear to reduce the risk of some cancers, perhaps by prevent-
ing 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 sulfora-
phane as 150 grams of mature broccoli. The sulforaphane levels in other cruciferous veg-
etables have not yet been calculated.Adverse Effects Associated with This Food
Enlarged thyroid gland (goiter). Cruciferous vegetables, including turnips, contain goitro-
gens, chemicals that 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 thyroid disorder. The goitrogens in turnips are progoitrin and gluconasturtin.