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.

    一直以来，人们都知道，吃十字花科蔬菜有助于预防癌症，如菜花等；但至于这类蔬菜是如何抑制癌细胞生长的至今还不清楚。

    加利福尼亚大学的研究人员于上周二发表研究报告称，他们通过一项最新研究发现了十字花科蔬菜抑制癌细胞生长的机理。

    研究结果在本月的《癌症学》期刊上发表。

    研究报告撰写人之一奥尔加•阿扎仁科说：“吃十字花科类蔬菜，如卷心菜及其‘兄弟’菜花和花椰菜等能够预防乳腺癌。这些蔬菜中所含的名叫‘异硫氰酸酯’（ITCs）的物质具有抗癌及防癌功效。”

    该研究重点关注的是其中一种名叫SFN的化学物质的抗癌功效。此前有动物试验发现，这种物质能够降低化学物质诱导乳腺肿瘤发生的几率。它也能够抑制人工培养的乳腺癌细胞的生长。

    研究人员得出了一个惊人的发现，SFN抑制人体内癌细胞生长的机理与抗癌药物抑制癌细胞分裂的方式相类似。然而，与那些植物源抗癌药物相比，SFN的“威力”要弱得多，因此毒性也小得多。

    研究人员称：“SFN可能是一种有效的抗癌物质，因为它能够抑制癌细胞生长，杀死可能癌变的细胞。”此外，它还能作为抗癌药物的补充，在不增加毒性的前提下，有效杀死癌细胞。