Vitamin C Szent-Györgyi was awarded the 1937 Nobel Prize in Medicine, and Haworth shared that year's Nobel Prize in Chemistry. In 1957, J.J. Burns showed that some mammals are susceptible to scurvy as their liver does not produce the enzyme -gulonolactone oxidase, the last of the chain of four enzymes that synthesize vitamin C. American biochemist Irwin Stone was the first to exploit vitamin C for its food preservative properties. He later developed the theory that humans possess a mutated form of the -gulonolactone oxidase coding gene. In 2008, researchers at the University of Montpellier discovered that in humans and other primates
Vitamin D and neurology vitamin D blood concentration standard for diagnosing hypovitaminosis D does not exist. In the past, hypovitaminosis D has been defined by blood concentrations lower than 20 ng/ mL. However, in more recent literature many researchers have considered 30 ng/ mL to be an insufficient concentration of vitamin D. Subnormal levels of vitamin D are usually caused by poor nutrition or a lack of sun exposure. Risk factors for hypovitaminosis D include premature birth, darker skin pigmentation, obesity, malabsorption, and older age. The brain requires the use of many neurosteroids to develop and function properly. These molecules are often identified as