Eijkman was sometimes called the reluctant father of vitamin research. He worked as a doctor in the former Dutch East Indies (now Indonesia). While on sick leave in the Netherlands he was asked to join a research project into the causes of beriberi, a tropical disease that killed many people at the time. Progress was slow as a number of assumptions, including the idea that it had a bacteriological causeagent, soon proved to be incorrect. After two years, in 1890, Eijkman discovered that eating unmilled whole grain rice prevented the disease and cured it.
Eijkman thought the bran and germ covering the rice contained an antibody that offered protection against the poison that – so he assumed – was produced by the bacterium that affected the nervous system and caused beriberi. Not until in 1916 was he willing to accept that a food deficiency could cause something as serious as beriberi. It was almost thirty years later that Eijkman's successors discovered the responsible vitamin, B1.
Eijkman worked as a professor at Utrecht University from 1898. His field of research and training was that of hygiene and forensic medicine, and he always had a particular interest in tropical diseases. Eijkman was awarded the Nobel Prize in 1930 but illness prevented him from travelling to Oslo to accept the prize in person, and he died a year later. Utrecht University founded the 'Eijkman Graduate School for Immunology and Infectious Diseases' in his memory.