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."

(Agencies via China Daily March 26, 2008)