While it has been known for some time that eating cruciferous vegetables, such as broccoli, can help prevent breast cancer, the mechanism by which the active substances in these vegetables inhibit cell proliferation was unknown -- until now.

    Scientists in University of California reported on Tuesday that their new research has shown how the healing power of these vegetables works at the cellular level.

    The study results was published in this month's journal Carcinogenesis.

    "Breast cancer can be protected against by eating cruciferous vegetables such as cabbage and near relatives of cabbage such as broccoli and cauliflower," said author Olga Azarenko. "These vegetables contain compounds called isothiocyanates which we believe to be responsible for the cancer-preventive and anti- carcinogenic activities in these vegetables."

    Their research focuses on the anti-cancer activity of one of these compounds, called sulforaphane, or SFN. It has already been shown to reduce the incidence and rate of chemically induced mammary tumors in animals. It inhibits the growth of cultured human breast cancer cells.

    The researchers made the surprising discovery that SFN inhibits the proliferation of human tumor cells by a mechanism similar to the way that the anticancer drugs inhibit cell division. However SFN is much weaker than these other plant-based drugs, and thus much less toxic.

    "SFN may be an effective cancer preventive agent because it inhibits the proliferation and kills precancerous cells," said the authors. It is also possible that it could be used as an addition to anticancer drugs to increase effective killing of tumor cells without increased toxicity.

    一直以來，人們都知道，吃十字花科蔬菜有助于預防癌癥，如菜花等；但至于這類蔬菜是如何抑制癌細胞生長的至今還不清楚。

    加利福尼亞大學的研究人員于上周二發表研究報告稱，他們通過一項最新研究發現了十字花科蔬菜抑制癌細胞生長的機理。

    研究結果在本月的《癌癥學》期刊上發表。

    研究報告撰寫人之一奧爾加•阿扎仁科說：“吃十字花科類蔬菜，如卷心菜及其‘兄弟’菜花和花椰菜等能夠預防乳腺癌。這些蔬菜中所含的名叫‘異硫氰酸酯’（ITCs）的物質具有抗癌及防癌功效。”

    該研究重點關注的是其中一種名叫SFN的化學物質的抗癌功效。此前有動物試驗發現，這種物質能夠降低化學物質誘導乳腺腫瘤發生的幾率。它也能夠抑制人工培養的乳腺癌細胞的生長。

    研究人員得出了一個驚人的發現，SFN抑制人體內癌細胞生長的機理與抗癌藥物抑制癌細胞分裂的方式相類似。然而，與那些植物源抗癌藥物相比，SFN的“威力”要弱得多，因此毒性也小得多。

    研究人員稱：“SFN可能是一種有效的抗癌物質，因為它能夠抑制癌細胞生長，殺死可能癌變的細胞。”此外，它還能作為抗癌藥物的補充，在不增加毒性的前提下，有效殺死癌細胞。