How vitamin A was found to be a Vitamin Vitamins are organic compounds that are essential to human metabolism, but that humans are unable to synthesize so they must be acquired through food. During evolution, we “simply” lost some enzymes required for their synthesis. Observations made before 1900: Nutritional deprivation caused corneal ulcers, blindness, and high mortality. Also, an unknown substance present in milk and egg yolk is essential for nutrition. In the early 20th century it was found that this unknown substance was fat soluble. The growth-supporting “accessory factor” in milk and egg yolk became known as ‘fat-soluble A’ in 1918 and then ‘vitamin A’ in 1920. Further research, … Continue reading Vitamin A in Skin Care