ABC Radio National's well-known philosopher and foodie Alan Saunders has died of pneumonia in hospital on Friday.

While working on his program The Philosopher's Zone on Thursday afternoon, Alan fell ill and was taken to hospital where his condition deteriorated overnight.

He died on Friday morning surrounded by colleagues and friends.

After joining Radio National in 1987, Dr Saunders founded The Food Program and worked as a presenter on By Design and Screen - a program about film and television.

"In his 25 years with Radio National, Alan made a substantial contribution to the intellectual discourse in Australia and certainly to the enjoyment of his audiences," ABC director of radio Kate Dundas said.

"He had both a distinctive voice and a distinguished mind - a great combination for a presenter of engaging and thought-provoking radio."

Born and educated in London, Dr Saunders studied philosophy at the University of Leicester, where he was also the president of the students' union.

He moved to Australia in 1981 to pursue research at the Australian National University's History of Ideas Unit, where he was subsequently awarded a PhD.

In 1992, Dr Saunders was awarded the Pascall Prize for critical writing and broadcasting.

In 2007 he was awarded the Australasian Association of Philosophy's Special Media Prize.

Dr Saunders was also the author of A is for Apple and Alanna.

Acting station manager Amanda Armstrong says Dr Saunders had an extraordinary mind.

"He was equally at home talking about Plato, the role of vampires in popular culture or the history of the restaurant," she said.

"He wrote like an angel, and had a deep knowledge of music, among many other areas, including philosophy, gastronomy, architecture, design and film."

Managing Director Mark Scott also expressed his sadness.

"Alan embodied Radio National’s commitment to intelligent, specialist broadcasting," he said.

"He was a trusted, authoritative voice for so many years. We will miss him as will his many listeners from all around Australia."

Tributes have also flowed on Twitter since news of his death broke this afternoon.

The ABC's Mark Colvin offered his condolences.

"Deeply shocked to hear of the death of Radio National stalwart, philosopher & foodie Alan Saunders. RIP."

This Sunday at 5.30pm, The Philosopher’s Zone will air the final part of Dr Saunders's Thinking Out Loud series, with Stathis Gourgouris, Professor of Classics at Columbia University.

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