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Boiling broccoli ruins its cancer-fighting properties, researchers say.
Brassica vegetables such as broccoli and brussels sprouts help to prevent cancer because they contain plant compounds called glucosinolates.
Scientists at the University of Warwick found that up to 77 per cent of the chemicals are removed from these vegetables by boiling. Steaming, microwaving and stir-frying preserved the substances and were healthier methods.
Many people who despise broccoli eat the vegetable because they think it is good for them. But if they rely on traditional boiling, they could be suffering pain with no gain, the findings suggest.
The researchers tested the effect of different preparations on four brassica vegetables - broccoli, brussels sprouts, cauliflower and green cabbage.
Glucosinolate loss after 30 minutes boiling was 77 per cent for broccoli, 58 per cent for sprouts, 75 per cent for cauliflower and 65 per cent for cabbage.
The vegetables were also steamed for 20 minutes, microwaved for three minutes and stir-fried for five minutes. None of these methods resulted in significant glucosinolate reduction.
Freezing and thawing resulted in up to a third of the compounds being lost, and up to 75 per cent was lost when the vegetables were finely shredded.
Professor Paul Thornalley, from Warwick Medical School, said: "If you want to get the maximum benefit from your five portions-a-day vegetable consumption, if you are cooking your vegetables boiling is out. You need to consider stir frying, steaming or microwaving them."
- NZPA
