Washington, June 23 (IANS): Captive black rhinos in zoos are facing a bizarre situation. The food served to them is good but the rich diet may put them at high risk for two common health problems: inflammation and insulin resistance.

"We are providing good, nutritious, high quality food. We are just learning that providing high quality food in excess can cause problems," said Pam Dennis, clinical assistant professor of veterinary preventive medicine at the Ohio State University.

Black rhinos are browsers that eat leaves, branches and parts of trees in the wild. Their zoo diet mainly consists of grass or hay, milled grains and fruits and vegetables.

"We now recognise that obesity in humans leads to increased inflammation and a whole cascade or problems ranging from heart disease to immune dysfunction. This is entering the vocabulary in zoo medicine, that obesity is much more than just a weight issue," Dennis said.

Across the globe, there are only about 5,000 black rhinos - a drop from an estimated 100,000 in the 1960s.

The study appeared in General and Comparative Endocrinology.