Carbohydrate


Carbohydrate
Mainly sugars and starches, together constituting one of the three principal types of nutrients used as energy sources (calories) by the body. Carbohydrates can also be defined chemically as neutral compounds of carbon, hydrogen and oxygen. Carbohydrates come in simple forms such as sugars and in complex forms such as starches and fiber. The body breaks down most sugars and starches into glucose, a simple sugar that the body can use to feed its cells. Complex carbohydrates are derived from plants. Dietary intake of complex carbohydrates can lower blood cholesterol when they are substituted for saturated fat. Carbohydrates are classified into mono, di, tri, poly and heterosaccharides. The smallest carbohydrates are monosaccharides such as glucose whereas polysaccharides such as starch, cellulose and glycogen can be large and even indeterminate in length. The energy produced by carbohydrates is 4 calories per gram. Proteins also provide 4 calories per gram. Fats are high-cal; they provide 9 calories per gram. Etymology: Carbohydrates are called carbohydrates because the carbon, hydrogen and oxygen they contain are usually in the proportion to form water with the general formula Cn(H2O)n.

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car·bo·hy·drate -.drāt, -drət n any of various neutral compounds of carbon, hydrogen, and oxygen (as sugars, starches, and celluloses) most of which are formed by green plants and which constitute a major class of animal foods

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n.
any one of a large group of compounds, including the sugar and starch, that contain carbon, hydrogen, and oxygen and have the general formula Cx(H2O)y. Carbohydrates are important as a source of energy: they are manufactured by plants and obtained by animals from the diet, being one of the three main constituents of food (see also fat, protein). All carbohydrates are eventually broken down in the body to the simple sugar glucose, which can then take part in energy-producing metabolic processes. Excess carbohydrate, not immediately required by the body, is stored in the liver and muscles in the form of glycogen. In plants carbohydrates are important structural materials (e.g. cellulose) and storage products (commonly in the form of starch). See also disaccharide, monosaccharide, polysaccharide.

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car·bo·hy·drate (kahr″bo-hiґdrāt) any of a class of aldehyde or ketone derivatives of polyhydric alcohols, particularly of the pentahydric and hexahydric alcohols. They are so named because the hydrogen and oxygen are usually in the proportion to form water, Cn(H2O)n; the most important include the small sugars as well as the large starches, glycogens, celluloses, and gums. See also saccharide.

Medical dictionary. 2011.

Look at other dictionaries:

  • carbohydrate — 1851, from carbo , comb. form of CARBON (Cf. carbon), + HYDRATE (Cf. hydrate) (n.), denoting compound produced when certain substances combine with water, from Gk. hydor water (see WATER (Cf. water) (n.1)). The name carbohydrate was given to… …   Etymology dictionary

  • Carbohydrate — Car bo*hy drate, n. [Carbon + hydrate.] (Physiol. Chem.) One of a group of compounds including the sugars, starches, and gums, which contain six (or some multiple of six) carbon atoms, united with a variable number of hydrogen and oxygen atoms,… …   The Collaborative International Dictionary of English

  • carbohydrate — [n] organic compound composed of carbon, hydrogen, and oxygen cellulose, dextrin, dextrose, disaccharide, fructose, galactose, glucose, glycogen, lactose, maltose, monosaccharide, polysaccharide, starch, sucrose, sugar; concept 478 …   New thesaurus

  • carbohydrate — ► NOUN ▪ any of a large group of compounds (including sugars, starch, and cellulose) which contain carbon, hydrogen, and oxygen, occur in foods and living tissues, and can be broken down to release energy in the body …   English terms dictionary

  • carbohydrate — [kär΄bō hī′drāt, kär′bəhī′drāt] n. [ CARBO + HYDRATE] any of certain organic compounds, including the sugars, starches, and celluloses, which usually have the general formula Cx (H2O) y: carbohydrates are subdivided into monosaccharides,… …   English World dictionary

  • carbohydrate — /kahr boh huy drayt, beuh /, n. any of a class of organic compounds that are polyhydroxy aldehydes or polyhydroxy ketones, or change to such substances on simple chemical transformations, as hydrolysis, oxidation, or reduction, and that form the… …   Universalium

  • Carbohydrate — Carbohydrates (from hydrates of carbon ) or saccharides (Greek σάκχαρον meaning sugar ) are the most abundant of the four major classes of biomolecules, which also include proteins, lipids and nucleic acids. They fill numerous roles in living… …   Wikipedia

  • carbohydrate — noun ADJECTIVE ▪ simple ▪ complex ▪ complex carbohydrates such as pasta ▪ refined ▪ unrefined VERB + CARBOHYDRATE …   Collocations dictionary

  • carbohydrate — I (New American Roget s College Thesaurus) n. sugar, starch (See organic matter). II (Roget s IV) n. Syn. starch, sugar, monosaccharide, disaccharide, polysaccharide, saccharide, glucose, sucrose, dextrose, fructose, lactose, galactose, maltose,… …   English dictionary for students

  • carbohydrate — UK [ˌkɑː(r)bəʊˈhaɪdreɪt] / US [ˌkɑrboʊˈhaɪˌdreɪt] noun Word forms carbohydrate : singular carbohydrate plural carbohydrates biology a) [countable/uncountable] a substance found in foods such as sugar, bread, and potatoes. Carbohydrates supply… …   English dictionary


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