Even George W Bush might think twice about eating broccoli if he knew how important it is for restoring the body's immunity and perhaps slowing down aging.

Broccoli contains a chemical called sulforaphane which switches on a set of antioxidant genes and enzymes in specific immune cells, which then combat the injurious effects of free radicals that can damage cells and lead to disease.

Broccoli is one of the ‘super foods’, most of which are cruciferous vegetables, which are known to produce antioxidants to defeat free radical damage to the body’s cells.

As the body ages, its own immune cells find it harder to combat free radical damage, and the resulting damage to cells and tissues is believed to be one of the causes of aging.

The immune restorative power of sulforaphane from broccoli was demonstrated by researchers at the David Geffen School of Medicine at UCLA.

Explaining his team’s research to the media, Dr. Andre Nel, the study's principal investigator and a clinical allergist and immunologist, said aging had always intrigued humans. While in recent years we have learned that free radicals are important in aging, he said most of the 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 defense pathways that the body uses to fight free radicals," he said.

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

"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."

Old Mice Show Broccoli Benefits

The UCLA team not only found that the direct administration of sulforaphane in broccoli reversed the decline in cellular immune function in old mice, but they witnessed similar results when they took individual immune cells from old mice, treated those cells with the chemical outside the body and then placed the treated cells back into a recipient animal.

In particular, the researchers discovered that dendritic cells, which introduce infectious agents and foreign substances to the immune system, were particularly effective in restoring immune function in aged animals when treated with sulforaphane.

New Drugs From Broccoli?

To investigate how the chemical in broccoli increased the immune system's response, the UCLA group confirmed that sulforaphane interacts with a protein called Nrf2, which serves as a master regulator of the body's overall antioxidant response and is capable of switching on hundreds of antioxidant and rejuvenating genes and enzymes.

Nel said that the chemistry leading to activation of this gene-regulation pathway could be a platform for drug discovery and vaccine development to boost the decline of immune function in elderly people.

He said these findings “offer a window” into how the immune system ages.

"This is a radical new way of thinking in how to increase the immune function of elderly people to possibly protect against viral infections and cancer," hesaid.

"We may have uncovered a new mechanism by which to boost vaccine responses by using a nutrient chemical to impact oxidant stress pathways in the immune system."

Eat Your Broccoli

“Dietary antioxidants have been shown to have important effects on immune function, and with further study, we may be adding broccoli and other cruciferous vegetables to that list," Nel said.

He suggested people of all ages, but particularly those over 50, regularly include these vegetables as part of a healthy diet.

The study, Nrf2 activation by sulforaphane restores the age-related decrease of TH1 immunity, was published online in the Journal of Allergy and Clinical Immunology.