About three-quarters of the genetic diversity once found in agricultural crops has been lost over the last century, the Food and Agriculture Organisation (FAO) said in a study.

While ethnic communities in far-flung parts of the world can pick from a wide range of fruits and vegetables, Western industrialised nations rely heavily on four commercial crops -- wheat, rice, corn and soy, the FAO said.

Traditional foods frequently contain very high levels of micronutrients that are good for the body, and the introduction of processed foods is causing health problems in some communities, it said.

"The shift away from traditional food resources to commercial, convenience foods is often accompanied by an increase in diet-related disorders like obesity, diabetes and high blood pressure," said Barbara Burlingame, FAO senior nutrition officer.

Globalisation threatens treasure troves that the researchers found in communities such as the Karens in Thailand, near the Myanmar border, where 661 inhabitants can choose from 387 food species, the FAO said.

Kenya's Maasai tribes enjoy 35 different species of herbs, leafy vegetables and wild fruits, while the Inuit of Baffin Bay in Canada's north eat 79 different wildlife foods including caribou meat and ringed seal, it found.

The study, titled "Indigenous People's Food Systems," was conducted with the Centre for Indigenous People's Nutrition and Environment at McGill University in Montreal.

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