Eating broccoli may protect against heart disease, US research suggests.
Broccoli may also have anti-cancer properties
Rats were fed an extract of the vegetable for a month, and the effect on their heart muscle was measured.
Compared with animals whose diet did not change, the hearts of the broccoli rats functioned better and displayed less damage when deprived of oxygen.
The Journal of Agricultural and Food Chemistry study suggests broccoli may trigger production of proteins which protect against heart damage.
The health benefits of broccoli have been widely touted, particularly in regard to its potentially protective qualities against cancer.
But working out both if and how this may be the case has proved a challenge.
Now researchers at the cardiovascular research centre at the University of Connecticut believe they have at least shown how the benefits may work in animal hearts.
The broccoli diet appears to persuade the body to produce a protein called thioredoxin, which protects against cell damage in the heart.
Broccoli contains sulforaphane, which is seen as particularly effective in triggering this process.
However, the lightly steamed version of the vegetable may be more powerful than the one which has been left to boil.
"If broccoli is over-cooked it loses a lot of its protective effect," said Professor Dipak Das, who led the research team.
The researchers are now looking into whether the vegetable and others of its family - including cabbage and Brussels sprouts - may also help fight other diseases.
"There is strong evidence to suggest that eating five portions of fruit and vegetables a day can help to reduce the risk of coronary heart disease," said June Davison of the British Heart Foundation.
"Broccoli can count as one of these portions. However different fruit and vegetables have different combinations of vitamins and minerals, so aim to eat a variety to get the most benefit."