How was Frederick Gowland Hopkins awarded the Noble Prize in Physiology or Medicine?

Name: Frederick Gowland Hopkins.
Country: United Kingdom.
Date of Birth: 20 June 1861.
Died: 16 May 1947.
Education: King’s College London Guy’s Hospital.
Subjects Of Study: Nutrient, Vitamin.
Known as: Vitamins, tryptophan, and glutathione.
Noble Prize Year: Nobel Prize for Peace in 1929, for his discovery of the growth-stimulating vitamins.