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Johns Hopkins University Study Shows Some Broccoli Sprout Varieties to Have 20 to 50 times More SGS than Mature, Cooked Broccoli

Reducing Risk of Some Cancers with Diet

With 10.3 million new cancer cases diagnosed each year worldwide, medical investigators are taking a closer look at how diet may help reduce cancer risk. Experts believe that as many as two-thirds of these cancers may be caused by diet and lifestyle factors. A number of studies indicate that diets rich in fruits and vegetables contribute to decreased risk of many types of cancers. Researchers are now investigating specific phytochemicals (natural plant chemicals), found in fruits and vegetables, that may serve as weapons against cancer and other diseases.¹ Phytochemicals number in the thousands, and only a small number of them have been identified and studied.

During the past eight years, in the culmination of decades of scientific research, Paul Talalay, M.D., and a team of researchers at Johns Hopkins University School of Medicine made a series of breakthrough discoveries in this area. Their scientific findings relating to SGS™ (sulforaphane glucosinolate), a compound found in broccoli, may help to explain the widely recognized scientific evidence indicating that populations consuming a diet rich in fruits and vegetables, and especially cruciferous vegetables such as broccoli, have a reduced risk of developing several types of cancers.^1-9 Other institutions around the world have also conducted research on the role of SGS in cancer prevention and protection. Following is a summary of their most significant findings. To date, research has been conducted in animals. Clinical studies are underway at Johns Hopkins to extend these observations to humans.

Chemoprotection

Dr. Talalay's initial research targeted the potential chemoprotective effects of certain vegetable varieties. "Chemoprotection is a deliberate effort to increase the body's defense systems against chemicals, including carcinogens, that can lead to disease," according to Dr. Talalay. "Chemoprotection may lower a person's risk of developing cancer by building up the body's own defenses, particularly through diet." Dr. Talalay's strategy of chemoprotection takes advantage of the body's Phase 2 detoxification enzymes that help neutralize cancer-causing chemicals, as well as free radicals, before they can damage DNA and initiate the development of cancer.

The Sulforaphane Discovery

As part of this research strategy, in 1992, Dr. Talalay and his colleagues at Johns Hopkins University isolated and identified sulforaphane, a natural compound found in broccoli. They found sulforaphane to be the most potent booster of Phase 2 enzymes, which stimulate the ability of animal cells to protect against disease.¹⁰

Antioxidant Activity of Sulforaphane

Sulforaphane exists in cruciferous vegetables such as broccoli and cabbage. In its precursor form, sulforaphane glucosinolate (SGS) functions as an indirect antioxidant. As such, this compound does not directly neutralize free radicals as do direct antioxidants like vitamins E and C and beta-carotene. Indirect antioxidants induce (or boost) the activity of the Phase 2 detoxification enzymes. According to Dr. Talalay, "These enzymes act as a defense mechanism, triggering broad spectrum antioxidant activity that neutralizes many free radicals, cycling over and over again before they can cause the cell damage that may cause mutations, leading to cancer."

Furthermore, Dr. Talalay says that the effects of these indirect antioxidants remain even after they have left the body - unlike direct antioxidants, which neutralize only one molecule of a radical at a time, and are destroyed in the process. The indirect antioxidant effects are long-lasting, triggering an ongoing process that continues to be effective and may last for days.

SGS Blocks Tumors in Animals

In 1994, Dr. Talalay and his group of researchers tested the efficacy of sulforaphane in animals. Their research found that sulforaphane blocked the formation of mammary tumors in rats treated with a potent carcinogen: The number of rats that developed tumors was reduced by as much as 60%, the number of tumors in each animal was reduced by 80%, and the size of the tumors that did develop was reduced by 75%. Furthermore, the tumors' appearance was delayed and they grew more slowly.¹¹

Most recently, researchers from the U.S. and Europe have further examined the effects of SGS in cancer models. Scientists at the American Health Foundation discovered that sulforaphane inhibited the formation of premalignant lesions in the colons of rats.¹² Furthermore, researchers in Toulouse, France found that sulforaphane induced cell death in human colon carcinoma cells. This study suggests that "in addition to the activation of detoxifying enzymes, induction of apoptosis [cell death] is also involved in the sulforaphane-associated chemoprevention of cancer."¹³ These results have not yet been validated in humans.

High Levels of SGS Found in Broccoli Sprouts

Dr. Talalay and his team next examined a wide range of broccoli plants to determine which had the highest levels of SGS. First, Dr. Talalay and his researchers found that many varieties of fresh and frozen broccoli differed significantly in the amounts of SGS they contained and, thus, in their ability to increase protective Phase 2 enzymes.

It was then discovered that as the plant grows older, the concentration of SGS decreased. Conversely, young plants (three-day-old sprouts) yielded much more concentrated enzyme-induced activity. Findings from this research demonstrated that certain varieties of three-day-old broccoli sprouts contained between 20 and 50 times the concentration of SGS as the mature, cooked vegetable.

Commercial broccoli is highly variable in SGS content. The researchers discovered that young broccoli sprouts, grown from the seeds of certain varieties of broccoli, can be produced under carefully standardized conditions to contain consistently high concentrations of SGS. Researchers found that on average one ounce of these special sprouts provided as much SGS as 1 1/4 pounds (20 ounces) of mature, cooked broccoli (20 times the concentration).

The Johns Hopkins University School of Medicine has received three patents for this SGS-enhanced broccoli sprout discovery, and the University licensed this patent so that broccoli sprouts could be carefully monitored to ensure they contain optimal levels of SGS. These sprouts are now available to the public as BroccoSprouts®.

Brassica Chemoprotection Laboratory

To facilitate further study based on the promising results of the animal research - and with support from philanthropists and the National Cancer Institute - Talalay founded the Brassica Chemoprotection Laboratory within Johns Hopkins University.

The Brassica Chemoprotection Laboratory is the first laboratory of its kind designed exclusively for the study of the chemoprotective properties of plants. Studies undertaken with Jed W. Fahey in the lab include:

1. testing a wide variety of edible plants for their ability to raise chemoprotective (Phase 2) enzymes;
2. cultivating those plants that exhibit the highest levels of this activity and determining conditions that will further increase activity; and
3. selecting, hybridizing and scientifically breeding plants to enhance chemoprotective potency.

Conclusion

The Johns Hopkins strategy and discoveries are consistent with what many epidemiologic studies have shown: Many cancers may be related to lifestyle or extrinsic factors and are, therefore, in principle, preventable. Johns Hopkins researchers continue to focus on SGS and other compounds from edible plants that may have potential chemoprotective effects. More research needs to be undertaken to confirm the benefits of SGS in humans, but, according to Dr. Talalay, the outlook is very promising. A percentage of BroccoSprouts broccoli sprouts sales are contributed to The Brassica Foundation for Chemoprotection Research, which supports further research into the link between nutrition and cancer.