A vitamin is an organic compound and a vital nutrient that an organism requires in limited amounts. An organic chemical compound (or related set of compounds) is called a vitamin when the organism cannot synthesize the compound in sufficient quantities, and it must be obtained through the diet; thus, the term "vitamin" is conditional upon the circumstances and the particular organism.
- 7.1: Vitamins: Basic Concepts
- Vitamins are organic compounds (meaning they contain Carbon) and they are vital nutrients that organisms require in limited amounts. Just like other essential nutrients, vitamins must be obtained from the diet since the organism can not make them (or can not make enough of them) for survival. Interestingly, not all organisms have the same vitamin requirements. Vitamins are classified as either: fat soluble (will dissolve in oil) or water soluble (will dissolve in water).
- 7.2: Fat Soluble Vitamins
- There are only four Fat Soluble Vitamins: Vitamin A, Vitamin D, Vitamin E and Vitamin K. What makes them "fat soluble" is the fact that they dissolve in fats and oils but they won't dissolve in water. If you've ever seen a vitamin E capsule, you already know that inside the capsule is an oily substance containing vitamin E. The Fat soluble vitamins are present in many foods but they are especially high in foods like nuts and seeds that contain a high concentration of fats and oils.
- 7.3: Water Soluble Vitamins
- Nine vitamins are considered water soluble, including: vitamin C and all of the B vitamins (Riboflavin, Niacin, Thiamin, B₆ , Folate, B₁₂, Pantothenic Acid and Biotin). In contrast to the four fat-soluble vitamins, water-soluble vitamins dissolve easily in water and, in general, are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption. Because they are not as readily stored, more consistent intake is important.