| >>Note: A vitamin is a nutrient that is an organic compound required in tiny amounts for essential metabolic reactions in a living organism. The term vitamin does not include other essential nutrients such as dietary minerals, essential fatty acids, or essential amino acids, nor does it encompass the large number of other nutrients that promote health but that are not essential for life. Vitamins are bio-molecules that act as catalysts and substrates in metabolism. When acting as a catalyst, vitamins are often bound to enzymes and are called prosthetic groups. Vitamins also act as coenzymes to carry chemical groups between enzymes. Although these roles in assisting enzyme reactions are vitamins' most important function, these molecules can also act in other parts of metabolism, such as cell signaling.[http://en.wikipedia.org/wiki/Vitamin] |
| | >>Note: Vitamins are classified as either water-soluble, meaning that they dissolve easily in water or fat-soluble vitamins, which are absorbed through the intestinal tract with the help of lipids (fats). In general, water-soluble vitamins are readily excreted from the body. Each vitamin is typically used in multiple reactions and, therefore, most have multiple functions. In humans there are 13 vitamins: 4 fat-soluble (A, D, E and K) and 9 water-soluble (8 B vitamins and vitamin C). [http://en.wikipedia.org/wiki/Vitamins#In_humans] |
| | Vitamin D, Ergocalciferol and Cholecalciferol |
| | Vitamin E, Tocopherol and Tocotrienol |
| | Vitamin A, Retinoids: retinol, retinoids and carotenoids |
| | Vitamin B5, Pantothenic acid |
| | Vitamin B12, Cyanocobalamin |
| | Vitamins in nutrition and diseases |
| | >>Note: Vitamins are essential for the normal growth and development of a multicellular organism. It requires certain vitamins and minerals to be present at certain times. If there is serious deficiency in one or more of these nutrients, a child may develop a deficiency disease. Even minor deficiencies may cause permanent damage. For the most part, vitamins are obtained with food, but a few are obtained by other means. For example, microorganisms in the intestine—commonly known as "gut flora"—produce vitamin K and biotin, while one form of vitamin D is synthesized in the skin with the help of natural ultraviolet in sunlight. Humans can produce some vitamins from precursors they consume. Examples include vitamin A, produced from beta carotene, and niacin, from the amino acid tryptophan. Once growth and development are completed, vitamins remain essential nutrients for the health maintenance. [http://en.wikipedia.org/wiki/Vitamins#In_nutrition_and_diseases] |
| | >>Note: Deficiencies of vitamins are classified as either primary or secondary. A primary deficiency occurs when an organism does not get enough of the vitamin in its food. A secondary deficiency may be due to an underlying disorder that prevents or limits the absorption or use of the vitamin, due to a “lifestyle factor”, such as smoking, excessive alcohol consumption, or the use of medications that interfere with the absorption or use of the vitamin. People who eat a varied diet are unlikely to develop a severe primary vitamin deficiency. In contrast, restrictive diets have the potential to cause prolonged vitamin deficits, which may result in often painful and potentially deadly diseases. Because human bodies do not store most vitamins, humans must consume them regularly to avoid deficiency. [http://en.wikipedia.org/wiki/Vitamins#Deficiencies] |
| | Side effects and overdose of vitamins |
| | >>Note: In large doses, some vitamins have documented side effects that tend to be more severe with a larger dosage. The likelihood of consuming too much of any vitamin from food is remote, but overdosing from vitamin supplementation does occur. At high enough dosages some vitamins cause side effects such as nausea, diarrhea, and vomiting. When side effects emerge, recovery is often accomplished by reducing the dosage. The concentrations of vitamins an individual can tolerate vary widely, and appear to be related to age and state of health. |
| | >>Note: Dietary supplements, often containing vitamins, are used to ensure that adequate amounts of nutrients are obtained on a daily basis, if optimal amounts of the nutrients cannot be obtained through a varied diet. Scientific evidence supporting the benefits of some dietary supplements is well established for certain health conditions, but others need further study. [http://en.wikipedia.org/wiki/Vitamins#Supplements] |
| | Governmental regulation of vitamin supplements |
| | >>Note: Most countries place dietary supplements in a special category under the general umbrella of foods, not drugs. This necessitates that the manufacturer, and not the government, be responsible for ensuring that its dietary supplement products are safe before they are marketed. Unlike drug products, that must implicitly be proven safe and effective for their intended use before marketing, there are often no provisions to "approve" dietary supplements for safety or effectiveness before they reach the consumer. Also unlike drug products, manufacturers and distributors of dietary supplements are not generally required to report any claims of injuries or illnesses that may be related to the use of their products. [http://en.wikipedia.org/wiki/Vitamins#Governmental_regulation_of_vitamin_supplements] |
| | Names in current and previous vitamin nomenclatures |
| | >>Note: The reason the set of vitamins seems to skip directly from E to K is that the vitamins corresponding to "letters" F-J were either reclassified over time, discarded as false leads, or renamed because of their relationship to "vitamin B", which became a "complex" of vitamins. [http://en.wikipedia.org/wiki/Vitamins#Names_in_current_and_previous_nomenclatures]] |
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