A South American tribe with a highly active lifestyle has the healthiest arteries of any population yet studied, say researchers.

The Tsimane people, who live in the Bolivian Amazon, spend most of every day hunting, fishing, farming and gathering wild fruits and nuts, and follow a carbohydrate-based diet containing little protein and fat.

Scientists who examined hundreds of men and women from the group found that almost nine out of 10 had clear arteries showing no risk of heart disease.

Even in old age most remained in astonishingly good health.