Eating broccoli may now prevent a heart attack or stroke, say researchers.

Cauliflower, sprouts and cabbage are some other vegetables which facilitate free flow of blood. A chemical found in the vegetable strengthens the body's defence system to keep the arteries unclogged.

Broccoli contains the highest levels of sulforaphane, along with rocket, kale and pak choi. Treatment with this compound initiated the protective effect of a protein called Nrf2 which reduces swelling in areas of arteries most prone to disease.

This further reduced the risk of atherosclerosis in which the walls of the arteries are thickened thus leading to angina, heart attack and stroke.

Dr Paul Evans, of the National Heart and Lung Institute at Imperial College, who led the research team, said: "Treatment with the natural compound sulforaphane reduced inflammation at the high-risk areas by 'switching on' Nrf2. Sulforaphane is found naturally in broccoli, so our next steps include testing whether simply eating broccoli, or other vegetables in their family, has the same protective effect. We also need to see if the compound can reduce the progression of disease in affected arteries."

Studies have also shown that a chemical in the vegetable boosts DNA repair i cells and may stop them from becoming cancerous. There is other evidence suggesting that eating broccoli helps reverse the damage that is caused by diabetes to heart blood vessels.