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Vitamins can serve as precursors to many organic cofactors (e.g., vitamins B 1, B 2, B 6, B 12, niacin, folic acid) or as coenzymes themselves (e.g., vitamin C). However, vitamins do have other functions in the body. [29] Many organic cofactors also contain a nucleotide, such as the electron carriers NAD and FAD, and coenzyme A, which carries ...
For the most part, vitamins are obtained from the diet, but some are acquired by other means: for example, microorganisms in the gut flora produce vitamin K and biotin; and one form of vitamin D is synthesized in skin cells when they are exposed to a certain wavelength of ultraviolet light present in sunlight.
Some "minerals" are essential for life, but most are not. [1] [2] [3] Minerals are one of the four groups of essential nutrients; the others are vitamins, essential fatty acids, and essential amino acids. [4] The five major minerals in the human body are calcium, phosphorus, potassium, sodium, and magnesium. [2]
Because they are soluble in water, excess B vitamins are generally readily excreted, although individual absorption, use and metabolism may vary. [7] The elderly and athletes may need to supplement their intake of B 12 and other B vitamins due to problems in absorption and increased needs for energy production.
Most of the elements needed for life are relatively common in the Earth's crust. Aluminium , the third most common element in the Earth's crust (after oxygen and silicon ), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it ...
Because the body does not manufacture certain fatty acids (termed essential fatty acids), they must be obtained through one's diet. Ethanol is not an essential nutrient, but it does provide calories. The United States Department of Agriculture uses a figure of 6.93 kilocalories (29.0 kJ) per gram of alcohol (5.47 kcal or 22.9 kJ per ml ) for ...
Furthermore, depending on the location of the double-bond in the fatty acid chain, unsaturated fatty acids are classified as omega-3 or omega-6 fatty acids. Trans fats are a type of unsaturated fat with trans -isomer bonds; these are rare in nature and in foods from natural sources; they are typically created in an industrial process called ...
Organic micronutrients are classified as vitamins, and inorganic micronutrients are classified as minerals. Nutrients can also be classified as essential or nonessential, with essential meaning the body cannot synthesize the nutrient on its own. [6] Nutrients are absorbed by the cells and used in metabolic biochemical reactions.