A depressed New Zealander cut off a finger, cooked it with vegetables and then ate it in a rare case of self-cannibalism, according to a report in the Australasian Psychiatry publication.

The 28-year-old man had not taken drugs or alcohol at the time and was said to suffer "episodes of low mood", according to the report's authors Erik Monasterio and Craig Prince.

They say it is one of only eight documented cases of self-cannibalism recorded in the world.

After eating one finger the man planned to dine on two more before deciding instead to seek medical treatment where he was diagnosed with moderate symptoms of depression.

"He felt extreme anger and for the first time fantasised about not only killing his assailants, but of eating them too," said the report.

"At the end of 2008, following another personal crisis, and while not being fully compliant with his medication, he spiralled into another episode of depression. He experienced significant insomnia and suicidal ideation, and ruminated for days about cutting off his fingers.

"In an effort to seek reprieve from these thoughts, he tied a shoelace around his (little) finger to act as a tourniquet and cut the finger off with a jigsaw.

"He then cooked it in a pan with some vegetables and ate its flesh. His plan was to amputate another two fingers the following day."

The report says the man informed mental health staff about his violent thoughts and of threatening to eat part of himself during previous episodes of depression.

"It is possible that his lack of violence and any offending behaviour, as well as his lack of psychosis, made clinicians somewhat complacent about his threats and that more drastic action was finally required by him," the report said.

"It may be that the act of actually cutting off his finger - and eating its flesh - made staff take him more seriously and provide the care and understanding that he longed for."

- AFP