As well as drinking from a creek and sleeping under a rocky overhang, Lester consumed eucalyptus leaves when his day-trip supplies ran out.

Apart from losing an estimated eight kilograms and suffering from dehydration, Lester did not appear to have been seriously harmed by his survival strategy.

However, two experts have recommended that people avoid eating or chewing eucalyptus leaves in an emergency situation, or any other plants that have not been proven edible.

Victorian Institute of Forensic Medicine associate professor of forensic medicine and forensic toxicology Dr Morris Odell said eucalyptus leaves contained a lot of chemicals including eucalyptus oil.

Part of Dr Odell’s work involves testing suspected criminals for drugs on behalf of the Victorian justice system.

“Eucalyptus oil can be toxic if ingested,” he said.

“Plants produce hundreds of different chemicals, any plant, and some of those chemicals are better known than others.

“So there could be other substances in eucalyptus leaves that could be toxic and there are hundreds of different species of eucalyptus and they are all a bit different and may produce different substances.”

Dr Odell said most of the research on the effects of eucalyptus on people had involved eucalyptus oil.

North Carolina State University has found that consuming large amounts of of eucalyptus oil was “extremely toxic” and could cause “nausea, vomiting, diarrhea and coma”.

Western Australia bush survival expert Bob Cooper has also told the ABC that people should not eat gum leaves as they produced chemicals to deter hungry animals.

Mr Cooper said people should avoid eating potentially unsafe items when lost as starvation was highly unlikely to kill them when compared to the risks of dehydration and exposure.

Dr Odell also advised against eating eucalyptus leaves.

“I don’t think it’s a real good idea,” he said.

“It’s not advisable to consume unknown plant material of any sort, whether it’s eucalyptus or not.

“The only animals that we know eat eucalyptus are koalas who have specialised digestive systems for that purpose and are completely different from human digestive systems.”