Broccoli is known for its anticancer properties but it could also boost the immune system in older people and slow down the effects of ageing, according to new research.

    A chemical found in cruciferous vegetables called sulforaphane was found to activate a number of antioxidant genes and enzymes in immune cells. These prevent free radicals from damaging cells.

    Free radicals are byproducts of normal body processes, such as the conversion of food into energy. They are a supercharged form of oxygen, which can cause oxidative tissue damage leading to disease - for example, triggering the inflammation process that causes clogged arteries.

    Oxidative damage to body tissues and organs is thought to be one of the major causes of ageing.

    "The mysteries of ageing have always intrigued man," wrote chief author Dr Andre Nel, from UCLA in the Journal of Allergy and Clinical Immunology.

    "While we have known for some time that free radicals are important in ageing, most of the past attention has focused on the mechanisms that produce free radicals rather than addressing the pathways used by the body to suppress their production.

    "Our study contributes to the growing understanding of the importance of these antioxidant defence pathways that the body uses to fight free radicals," said Dr Nel.

    "Insight into these processes points to ways in which we may be able to alleviate the effects of ageing."

    The delicate balance between pro-oxidant and antioxidant forces in the body could determine the outcome of many disease processes that are associated with ageing, including cardiovascular disease, degenerative joint diseases and diabetes, as well as the decline in efficiency of the immune system's ability to protect against infectious agents.

    "As we age, the ability of the immune system to fight disease and infections and protect against cancer wears down as a result of the impact of oxygen radicals on the immune system," Nel said.

    "Our defence against oxidative stress damage may determine at what rate we age, how it will manifest and how to interfere in those processes," Nel said.

    "In particular, our study shows that a chemical present in broccoli is capable of stimulating a wide range of antioxidant defence pathways and may be able to interfere with the age-related decline in immune function."

    花椰菜具有聞名的抗癌功能，但是一項新的研究表明，它也能夠刺激中老年人的免疫系統并且延緩衰老。

    業已發現，在十字花科蔬菜中發現的一種被稱為蘿卜硫素的化學成分，能夠活化免疫細胞內的許多抗氧化劑基因和酶。它們能阻止自由基破壞細胞。

    自由基是正常生理過程例如食物轉化為能量過程的副產物。它們是超動力形式的氧，可能引起組織的氧化損傷而導致疾病--例如觸發導致動脈堵塞的炎癥過程。

    對身體組織和器官的氧化損傷被認為是衰老的最主要原因之一。

    "衰老之謎始終讓人感興趣，" 加州大學洛杉磯分校《變態反應和臨床免疫學雜志》的首席作家安德烈·訥爾博士寫道。

    "當我們已經有一段時間知道自由基是衰老的重要因素的時候，過去的大多數注意力都集中在自由基的產生機理上，而不是致力于由身體采取途徑來抑制它們的產生。

    "我們的研究有助于擴大理解這些由身體用來對抗自由基的抗氧化劑防御途徑的重要性，"訥爾博士說。

    "深入了解這些過程向我們指出了可能減緩衰老作用的途徑。"

    身體中促氧化劑和抗氧化劑之間的微妙平衡可能決定很多與衰老有關的疾病過程的結果，這包括心血管疾病、退行性關節疾病和糖尿病，以及是免疫系統防止感染的能效的下降。

    "當我們變老時，免疫系統抵御疾病和傳染病以及預防癌癥的能力，由于氧自由基對免疫系統作用的結果而削弱，"訥爾說。

    "我們對抗氧化應激傷害的防御能力可能決定我們以什么速度衰老、它將如何體現以及如何去干預那些過程，"訥爾說。

    "特別是，我們的研究表明，花椰菜中存在的一種化學物質能夠刺激各式各樣的抗氧化劑防御途徑，并且能夠干預免疫功能因年齡關系的下降。"