Food of the Week: Broccoli - Protection against Cancer
January 30th, 2008 | by askadmin |Broccoli is a member of the cabbage family, and is closely related to cauliflower. Its cultivation originated in Italy. Broccolo, its Italian name, means “cabbage sprout.” Because of its different components, broccoli provides a range of tastes and textures, from soft and flowery (the floret) to fibrous and crunchy (the stem and stalk). Do not let the smell of the sulfur compounds that are released while cooking keep you away from this highly nutritious vegetable.
Protection against Cancer
Like other cruciferous vegetables, broccoli contains the phytonutrients sulforaphane and the indoles, which have significant anti-cancer effects. Research on indole-3-carbinol shows this compound helps deactivate a potent estrogen metabolite (4-hydroxyestrone) that promotes tumor growth, especially in estrogen-sensitive breast cells, while at the same time increasing the level of 2-hydroxyestrone, a form of estrogen that can be cancer-protective. Indole-3-carbinol has been shown to suppress not only breast tumor cell growth, but also cancer cell metastasis (the movement of cancerous cells to other parts of the body).
Scientists have found that sulforaphane boosts the body’s detoxification enzymes, potentially by altering gene expression, thus helping to clear potentially carcinogenic substances more quickly. When researchers at Johns Hopkins studied the effect of sulphoraphane on tumor formation in lab animals, those animals given sulforaphane had fewer tumors, and the tumors they did develop grew more slowly and weighed less, meaning they were smaller.
A study published in the cancer journal, Oncology Report demonstrated that sulforaphane, which is a potent inducer of Phase 2 liver detoxification enzymes, also has a dose-dependent ability to induce cell growth arrest and cell death via apoptosis (the self-destruct sequence the body uses to eliminate abnormal cells) in both leukemia and melanoma cells.
Sulforaphane may also offer special protection to those with colon cancer-susceptible genes, suggests a study conducted at Rutgers University and published online in the journal Carcinogenesis.
In this study, researchers sought to learn whether sulforaphane could inhibit cancers arising from one’s genetic makeup. Rutgers researchers Ernest Mario, Ah-Ng Tony Kong and colleagues used laboratory mice bred with a genetic mutation that switches off the tumor suppressor gene known as APC, the same gene that is inactivated in the majority of human colon cancers. Animals with this mutation spontaneously develop intestinal polyps, the precursors to colon cancer.
The study revealed that in animals fed sulforaphane, tumors were smaller, grew more slowly and had higher apoptotic (cell suicide) indices. Additionally, those fed a higher dose of sulforaphane had less risk of developing polyps than those fed a lower dose.
The researchers found that sulforaphane suppressed certain kinase enzymes. Kinases are cell signaling enzymes that are present not only in animals, but also in humans. The kinases suppressed by sulforaphane signal celluar activites that promote colon cancer. According to lead researcher, Dr. Kong, “Our study corroborates the notion that sulforaphane has chemopreventive activity…Our research has substantiated the connection between diet and cancer prevention, and it is now clear that the expression of cancer-related genes can be influenced by chemopreventive compounds in the things we eat.”
Another study, published in Cancer, the journal of the American Cancer Society, looked at indole-3-carbinol (I3C), a naturally occurring component of Brassica vegetables, such as broccoli, cabbage, and Brussels sprouts. I3C has been recognized as a promising anticancer agent against certain reproductive tumor cells. This laboratory study evaluated I3C’s effects on cell cycling progression and cancer cell proliferation in human prostate cancer cells. I3C was shown to suppress the growth of prostate cancer cells in a dose-dependent manner by blocking several important steps in cell cycling and also to inhibit the production of prostate specific antigen (PSA), a protein produced by the prostate whose rising levels may indicate prostate cancer. Researchers noted that the results of this study demonstrate that “I3C has a potent antiproliferative effect” in human prostate cancer cells, which qualifies it as “a potential chemotherapeutic agent” against human prostate cancer.
New research has greatly advanced scientists’ understanding of just how Brassica family vegetables such as broccoli, cabbage, cauliflower, kale and Brussels sprouts help prevent cancer. When these vegetables are cut, chewed or digested, a sulfur-containing compound called sinigrin is brought into contact with the enzyme myrosinase, resulting in the release of glucose and breakdown products, including highly reactive compounds called isothiocyanates. Isothiocyanates are not only potent inducers of the liver’s Phase II enzymes, which detoxify carcinogens, but research recently conducted at the Institute for Food Research in the U.K. shows one of these compounds, allyl isothicyanate, also inhibits mitosis (cell division) and stimulates apoptosis (programmed cell death) in human tumor cells.