Christiaan Eijkman (August 11, 1858, Nijkerk – November 5, 1930, Utrecht) was a Dutch physician and pathologist whose demonstration that beriberi is caused by poor diet led to the discovery of vitamins. Together with Sir Frederick Hopkins, he received the Nobel Prize for Physiology or Medicine.
Although Eijkman had been sent to Indonesia to study Beriberi, the discovery of the cause was accidental. He noticed the symptoms in some chickens used in his laboratory when their feed had been altered temporarily. Eijkman was unable to continue his research due to ill health, but a study by his friend Adolphe Vorderman confirmed the link between polished rice and the disease. Eventually it was determined the missing compound that was causing Beriberi was vitamin B1, thiamine.