LONDON (Reuters) - Turmeric, a spice used extensively in Asia as a key ingredient of curry, may be protecting children against leukemia, a scientist said on Thursday.

Rates of the blood cancer have been rising steadily for the past 50 years but its incidence in Asia is much lower than in the West.

Professor Moolky Nagabhushan, of the Loyola University Medical Center in Chicago, told a conference that factor could be due, at least partly, to turmeric.

"Some of the known risk factors that contribute to the high incidence of childhood leukemia are the interaction of many lifestyle and environmental factors," he said.

Scientists suspect some children are born with a predisposition to the illness, which occurs most often in children aged 1-4, but that they do not develop the disease unless it is triggered by environmental factors.

Infections, viruses, radiation, pesticides and chemicals are among the suspected culprits.

"Our studies show that turmeric -- and its coloring ... curcumin -- in the diet mitigate the effects of some of these risk factors," Nagabhushan added.

He and his colleagues showed that the spice irreversibly inhibits the multiplication of leukemia cells in laboratory studies and seems to protect against damage caused by cigarette smoke and eating certain processed foods.

Dr Marilyn Kwan, of the University of California, Berkeley, presented separate results of a study of more than 300 children which showed the benefits of eating healthy foods.

"We found that regular consumption of oranges and/or bananas during the first two years of life was associated with a reduced risk of childhood leukemia," Kwan said.

"These findings are consistent with the protective role of fruits and vegetables observed in adult cancers," she added.

Oranges are rich in vitamin C and bananas have high levels of potassium, both of which are thought to protect against cancer.

The week-long childhood leukemia conference is organized by the British charity Children with Leukemia.