It looks like a carrot, it is rich in carotene - but it's a banana that could save lives in the tropics. The karat of Pohnpei, one of the volcanic islands of Micronesia in the Pacific, has been pronounced one of the richest sources of vitamin A in the Pacific.

According to New Scientist today, Lois Englberger, a food researcher, and a colleague screened 21 versions of the banana native to the island, and found 15 of them could supply at least half the daily need for vitamin A.

But the karat emerged as the solid-gold source. The bright orange fruit contained 25 times the beta carotene of the Cavendish banana found in British and US supermarkets. Beta carotene is a precursor for vitamin A.

"Bananas are a luxury to us, but an important food source in many parts of the world," said Christopher Leaver, professor of plant science at the University of Oxford. "So I think it's good news."

Vitamin A deficiency is a form of malnutrition and a leading cause of blindness in the developing world. Some researchers estimate it could lie behind one child death in three on Pohnpei. A 10th of the children on the island are believed to have deteriorating eyesight.

European children get their vitamin A from fish oils, liver, butter and egg yolk, all in short supply on windswept coral atolls and steep volcanic islands.

Pacific islanders who once lived off staples such as breadfruit and ripe mangoes now eat polished white rice and other imported foods, and the hazards of malnutrition have grown.

Karat is a local variety of the Musa troglodytarum or Fe'i banana. The plant has traditionally provided medicine, fibre, leaves for cooking and food for livestock.