Eating broccoli twice a week could lower the risk of cancer, type-two diabetes and heart disease, scientists suggest.
Antioxidants such as phenols and flavonoids found in the vegetable are thought to help the body fight off disease.
Scientists believe eating broccoli - or other vegetables from the Brassica group - every three to four days gives enough of these compounds to improve the immune system by stopping inflammation.
Researchers at the University of Illinois in the US are trying to breed vegetables with mega-doses of the antioxidants, in the hope of creating a true "superfood".
Geneticist Dr Jack Juvik, who is leading the project, said: "We need inflammation because it's a response to disease or damage, but it's also associated with initiation of a number of degenerative diseases. People whose diets consist of a certain level of these compounds will have a lesser risk of contracting these diseases."