Broccoli Sprouts

People who eat lots of produce -- especially vegetables -- lower their risk of developing many common cancers, such as malignancies of the breast, lung, stomach, and prostate. Based on this common observation, the National Cancer Institute and numerous other public and private health organizations now advocate that people eat at least five servings of fruits and vegetables daily.

According to new survey data compiled by the U.S. Department of Agriculture, 60 percent of the population fails to meet its recommended intake of vegetables -- three to five servings per day (based on an individual’s size and calorie intake) -- and 75 percent of us don’t eat the recommended 2 to 4 servings of fruits daily. Indeed, 48 percent of us fail to down even one serving of fruit daily, an amount equal to one medium apple or 3/4 cup of fruit juice.

Dark green vegetables are among those that have been associated most strongly with cancer protection. Yet a typical U.S. resident eats no more than one serving a week of such vegetables through age 30 and then 1.2 servings per week after that.

Broccoli appears especially beneficial -- owing to its relatively high concentrations of sulforaphane, a compound that turns on detoxifying enzymes in the body (SN: 3/21/92, p. 183). Indeed, over the past few years researchers at the Johns Hopkins Medical Institutions in Baltimore have demonstrated that in animals exposed to chemical carcinogens, diets rich in sulforaphane dramatically cut cancer development.
Click here for an extract of the Johns Hopkins study

A new report out of Hopkins’ Brassica Chemoprevention Laboratory, recommended enriching the diet with sulforaphane. In the Sept. Proceedings of the National Academy of Sciences (PNAS), Paul Talalay and his team at Hopkins reported finding that newly sprouted seeds of broccoli and related members of the mustard (Brassica) family contain a chemical -- glucoraphanin -- that is converted into sulforaphane when the plant’s cell walls are broken, as during chewing. What happens is that a normally sequestered enzyme, known as myrosinase (pronounced my-ros-i-nace), gets released and triggers the glucoraphanin's transformation into sulforaphane.

Knowing this, Talalay says, "I cannot eat any of these [brassicas] now without chewing and waiting for the bite that occurs -- a sudden sharp taste." The same reaction causes the delayed kick to a peppery radish as it’s eaten. Owing to this myrosinase reaction, Talalay says, brassica sprouts "are much more interesting than alfalfa sprouts, which I think taste like straw." And the good news for people who don’t like or can’t tolerate broccoli, he says, is that broccoli sprouts don’t taste like broccoli.

In their new study, Talalay, Jed W. Fahey and Yuesheng Zhang grew different brassicas from seeds to determine when the sulforaphane precursor developed. And they found it present in the seed in startling concentrations. As the seed sprouted, it didn’t make any more, but it also didn’t lose any. So 3-day-old seedlings still represented a particularly enriched source of the glucoraphanin.

While young broccoli sprouts exhibited high concentrations of the sulforaphane precursor, so did those of related plants -- including arugula, bok choy, Brussels sprouts, cabbage, cauliflower, Chinese cabbage, collards, water cress, daikon, kale, kohlrabi, mustard, and conventional turnips. Sprouted seeds of each of these plants contain 10 to 100 times as much of the cancer-inhibiting compound as do mature, field grown plants.

Among these, broccoli and cauliflower cultivars invariably proved the top performers. To measure a cultivar’s potential anticancer activity, they extracted materials from its sprouts and ran them through an assay that measured their ability to activate certain detoxifying enzymes known as phase-2 enzymes.

They quantified the effect of these compounds in terms of their ability to increase the activity in a test tube of a common phase-2 enzyme (quinone reductase). One unit of activity corresponded to a doubling in this enzyme’s activity. Seed dealers offer some 80 different cultivated varieties of broccoli alone, and Talalay’s team found that there was wide variability in what a given cultivar could deliver. In their new study, each gram of 3-day-old broccoli sprouts exhibited 92,500 to 769,000 units of activity. Cauliflower sprouts ranged from 50,000 to 560,000 units per gram.

Mature broccoli not only contains glucoraphinin but also a host of related compounds not seen in the sprouts. Mostly indole glucosinolates, these additional chemicals have evolved to detoxify foreign compounds in our diet, usually through the activation of both phase-2 enzymes and a class of enzyme systems called phase-1.

The phase-1 systems tend to take a fairly nonreactive compound, such as the polycyclic aromatic hydrocarbons formed during combustion, and subtly alter them to make them slightly more water soluble. It’s a step that makes it easier for the body to excrete them.

Agents that activate phase-1 enzymes, however, "occasionally react with negatively charged bases in our DNA, causing damage and setting in motion mutations and carcinogenesis," Talalay says. "So while most chemicals that enter the body are in themselves innocuous, some can be converted by phase-1 enzymes into highly reactive carcinogens."

Phase-2 enzymes can trigger antioxidant reactions and other chemical changes that can often defuse toxic transformations initially wrought by the phase-1 enzymes. This has led some cancer biologists to speculate that whether a potential carcinogen damages DNA will depend on the balance between active phase-1 and phase-2 enzymes, Talalay explains. It’s also led his lab to seek out dietary constituents -- like sulforaphane and its precursor -- that selectively activate phase-2 enzymes only. And that’s another advantage the sprouts have over the mature plant, he says: They trigger the preferential phase-2 enzyme activity almost exclusively.

"I see his point" -- why focusing on phase-2 enzyme inducers appears so rational, says cancer researcher John M. Pezzuto of the University of Illinois at Chicago. "On the other hand, I don’t see that anyone is saying that normal, mature broccoli is dangerous." Indeed, he says, "I personally find it difficult to believe that the phase-1 enzyme inducers in our diet are hazardous." However, he says that until there is a better understanding of the overall balance of these enzymes and their effect on human health, "perhaps it is prudent to stick with [advocating a boosting of intake] of just these phase-2 enzyme inducers."

Marion Nestle is less convinced. Head of nutrition and food studies at New York (City) University, she jokes that "no rational person can understand this arcane world of phase-1 and phase-2 enzymes" -- at least how they play out in terms of effects in the body. In a commentary slated for publication in an upcoming issue of the PNAS, she cites work by Bruce Ames indicating that even phase-2 enzyme systems can sometimes transform a chemical from nontoxic to toxic.

Though she acknowledges that, in general, phase-2 enzymes are less likely than phase-1 enzymes to do this, she says that it’s still too early to understand what the significance of modifying dietary sulforaphane intake will be. Then again, she adds, it’s hard to imagine anyone overdosing on sprouts. "So if you want to eat broccoli sprouts, go ahead," she says.

See other studies on Sulforaphane

See below for a sample of the Fortified Flax Jar

For each jar purchased we contribute to the AIDS/HIV Awareness (ARAI) Program that helps mal-nourished children in Africa and other parts of the world (http://aidshivawareness.org)

Each jar contains 180gm of natural organic
flax hulls with 3-day old broccoli sprouts

The above information is provided for general educational purposes only. It is not intended to replace competent health care advice received from a knowledgeable healthcare professional. You are urged to seek healthcare advice for the treatment of any illness or disease.
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