Understanding Vitamins

Your body needs at least 11 specific vitamins: vitamin A, vitamin D, vitamin E, vitamin K, vitamin C, and the members of the B vitamin family: thiamin (vitamin B1), riboflavin (B2), niacin, vitamin B6, folate, and vitamin B12. Two more B vitamins — biotin and pantothenic acid — are now believed valuable to your well-being as well. And one unusual compound called choline has recently received some favorable mention. You need only miniscule quantities of vitamins for good health.
In some cases, the recommended dietary allowances (RDAs), determined by the National Research Council, may be as small as several micrograms (1⁄1,000,000 – that’s one one-millionth — of a gram). Nutritionists classify vitamins as either fat soluble or water soluble, meaning that they dissolve either in fat or in water. If you consume larger amounts of fat-soluble vitamins than your body needs, the excess is stored in body fat. Excess water-soluble vitamins are eliminated in urine. Large amounts of fat-soluble vitamins stored in your body may cause problems. With watersoluble vitamins, your body simply shrugs its shoulders, so to speak, and urinates away most of the excess.
Medical students often use mnemonic devices — memory joggers — to remember complicated lists of body parts and symptoms of diseases. Here’s one I use to remember which vitamins are fat-soluble: “All Dogs Eat Kidneys.” This saying helps me remember that vitamins A, D, E, and K are fat-soluble.
All the rest dissolve in water.