Magazine: Maclean's Magazine
Issue: May 23, 1994
Title: Nature's cancer fighter
Author: Tom Fennell


As a child, Bruce Rand says, he ``never heard tell of broccoli.'' The 44-year-old farmer now not only eats the green vegetable two or three times a week,
but grossed over $1 million in 1993 growing it on 425 acres of land in Nova
Scotia's fertile Annapolis Valley. Rand, one of Canada's largest broccoli
producers, began growing the vegetable exclusively in 1985, at a time when
demand for it was increasing rapidly among health-conscious Canadians. Almost
a decade later, its popularity shows no sign of peaking. In fact, the results
of a recent five-year study at Johns Hopkins University in Baltimore seem
certain to gave broccoli growers another boost. Researchers at the university
said last month that they had succeeded in isolating a cancer-fighting
chemical in broccoli known as sulforaphane. When the agent was injected into
rats, it discouraged the formation of mammary cancer tumors. As broccoli's
reputation continues to grow, Rand, for one, plans to keep expanding his
operation: ``We're going to ride the wave.''

   Sulforaphane does appear to be a powerful cancer-fighting agent. Dr. Paul
Talalay, the scientist who headed the Johns Hopkins research project, said
that rats were injected with various amounts of synthetic sulforaphane as well
as dimethyl benzanthracene, which is known to help trigger mammary cancer. For
comparative purposes, other rats received only the carcinogen. Of the latter
group, 68 per cent developed cancer. By contrast, cancer appeared in only 35
per cent of the rats that received low doses of sulforaphane, and just 26 per
cent of the rodents receiving high doses. Sulforaphane also seemed to retard
both the size and the number of tumors that did develop. Said Talalay:
``Sulforaphane is an potent detoxifier.''

   According to the researchers, sulforaphane works by boosting the body's
natural enzyme defences against chemicals that cause cancer. Talalay said that
as the body ages, cancer-causing agents build up in cells through the normal
intake of food and air. But when sulforaphane reaches one of those cells it
activates a group of proteins called Phase 2 enzymes. The enzymes then convert
carcinogens into harmless products, which are then removed from the body.
``The experiments did not reveal how much broccoli you should eat,'' said
Talalay. ``But we can say that eating vegetables several times a day reduces
the risk of cancer.''

   The researchers' next task is to attempt to duplicate the results of their
sulforaphane experiments with humans. That will involve feeding vegetables
with enzyme-inducing abilities to humans. ``We want to determine if we can
boost the level of cancer-fighting enzymes in humans,'' Talalay said. He
stressed, however, that there is no evidence the chemical can reduce or stop
cancers that have already developed.

   The Johns Hopkins team is now also trying to determine which vegetables
have the highest concentrations of sulforaphane or sulforaphane-like activity,
and whether it is possible to increase the amount of the chemical in the
plants. Broccoli is a member of the Cruciferae family, which also includes
brussels sprouts, cabbage, cauliflower and rutabaga. While most cruciferous
vegetables contain sulforaphane, the amount of the chemical in the plants
fluctuates greatly from one strain to another. Eventually, scientists hope to
be able to tell consumers which cruciferous plants offer the greatest
protection against cancer.

   The latest findings seem to support recent changes in the Canadian
government's food guide to healthy eating. In 1992, in an attempt to shift
Canadian diets away from red meat, the department of health amended the food
guide to increase the number of recommended fruit and vegetable servings from
five to 10 a day. (A typical serving might consist of an apple or orange, or
half a cup of vegetables.) According to Susan Sutherland, a dietician with the
Ottawa-based Canadian Produce Marketing Association, people who want to boost
their levels of protective enzymes should eat a variety of cruciferous
vegetables. To avoid destroying the beneficial chemical, vegetables should be
cooked only for a few minutes, if at all. ``It looks like mother was right all
along,'' said Sutherland. Parental admonitions to eat those vegetables will
likely keep Bruce Rand busy for many years to come.