Vitamin and C dissolve into the water when a vegetable is boiled, and are then lost when the water is discarded. The body's stores for different vitamins vary widely; vitamins A, D, and B are stored in significant amounts, mainly in the liver, and an adult's diet may be deficient in vitamins A and D for many months and B in some cases for years, before developing a deficiency condition. However, vitamin B (niacin and niacinamide) is not stored in significant amounts, so stores may last only a couple of weeks. For vitamin C, the first symptoms of scurvy in experimental
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