Gram for gram watercress is a better source of iron, calcium magnesium, zinc and manganese, and vitamins C, B1, B6, K and E than most other vegetables according to research from the United Kingdom.

Watercress - a slightly peppery tasting semi-aquatic plant occasionally found growing virtually wild in temperate climate farm dams, ponds and waterways - is also packed with antioxidants such as beta-carotene and vitamin A equivalents.

And while broccoli, blueberries, kale and sweet potatoes are often quoted as horticultural crops rich in health-fostering nutrients such as antioxidants, glucosinolates and phytochemicals (bioactive plant compounds), watercress has up to four times the antioxidant content say researchers at the University of Ulster in Northern Ireland.

These nutritional characteristics make it particularly good for improving the skin and eye health.

Watercress's high content of lutein and zeaxathin carotenoids also help absorb potentially cell-damaging free radicals, often over-produced in humans exposed to city pollution.

Results from the Ulster clinical trials found human cells treated with watercress extract slowed the growth of cancer cells an stimulated the ability of cells to resist DNA-damaging agents believed to induce cancer.

The benefits were greatest in smokers who tended to have lower antioxidant levels than non-smokers.

While watercress consumption in Australia is minimal, in the UK it is a popular salad mix ingredient with spinach and rocket.