The word autophagy derives from two Greek words meaning “self-eating”, and is a process for degrading and recycling cellular components.
The concept emerged in the 1960's but it was not until the early 1990's and Ohsumi's pioneering studies of bakers yeast which identified 15 genes that regulate the "self eating" process.
"Ohsumi's discoveries led to a new paradigm in our understanding of how the cell recycles its content," said Thomas Perlman, Secretary of the Nobel Committee at Sweden's Karolinska Institute when awarding the prize of SEK 8 million.
The Nobel Assembly said that the 71-year-old Japanese microbiologist's work is also important to help explain what goes wrong in a range of diseases, from cancer to Parkinson's.
The prize for Physiology or Medicine is the first of the Nobel prizes awarded each year. The winners of the physics, chemistry and peace prizes are to be announced later this week.