Scientists in the US may have found a way to optimise the powerful anti-cancer compound found in the common vegetable broccoli.
Sulphoraphane, identified in previous research as an antioxidant and therefore anti-cancer agent, is present in broccoli but the heating process destroys the enzyme needed to product these chemicals.
However a report in this month's New Scientist describes research presented recently by Nathan Matusheski, from the University of Illinois at Urbana-Champaign, that could offer a solution.
Speaking at a meeting of the the American Chemical Society, Matusheski said that raw broccoli contains only small amounts of sulphoraphane. Testing crushed raw broccoli in the lab, to mimic chewing, the researcher found that its cells rupture, releasing an enzyme that produces the potent chemicals. He explained further that in 'common supermarket broccoli', 20 per cent of the sulphoraphanes are the anti-carcinogenic kind, which have an extra sulphur atom in each molecule. The rest lacks this crucial sulphur and has no cancer-fighting capability.
However in broccoli that had been heated to 60°C, the relative levels were reversed, favouring the anti-cancer compound, according to the New Scientist report.
It continues that a protein in broccoli called ESP has a key role in changing levels of the sulphur-poor sulphoraphane. By heating the broccoli, the researcher found that the temperature destroyed the ESP, boosting sulphoraphane levels. But cooking broccoli also destroys the enzyme that produces sulphoraphanes in the first place, he said.
The researcher suggested eliminating the genes that code for the ESP protein to guarantee high levels of the health-promoting chemical. This could be done by making hybrids with wild strains, according to the report, or by gene silencing.
This is not the first time scientists have recognised the nutraceutical potential of the broccoli plant. A UK/US project has created a broccoli variation with higher than normal levels of glucosinolates, which are not active in the body, but their breakdown products are thought to help detoxify carcinogens and suppress the growth of existing cancerous tumours.