page_title: Human nutrition
section_title: Carbohydrates
hierarchical_section_title: Human nutrition / Nutrients / Carbohydrates
context_page_description: Human nutrition deals with the provision of essential nutrients in food that are necessary to support human life and good health. Poor nutrition is a chronic problem often linked to poverty, food security or a poor understanding of nutrition and dietary practices and poor knowledge about nutrients required by the body at various stages of life to prevent deficiency of nutrients in body which can have adverse effects on body. Malnutrition and its consequences are large contributors to deaths, physical deformities and disabilities worldwide. Good nutrition is necessary for children to grow physically and mentally, and for normal human biological development.
context_section_description: Carbohydrates may be classified as monosaccharides, disaccharides or polysaccharides depending on the number of monomer (sugar) units they contain. They are a diverse group of substances, with a range of chemical, physical and physiological properties. They make up a large part of foods such as rice, noodles, bread, and other grain-based products, but they are not an essential nutrient, meaning a human does not need to eat carbohydrates. The brain is the largest consumer of sugars in the human body, and uses particularly large amounts of glucose, accounting for 20% of total body glucose consumption. The brain uses mostly glucose for energy; if glucose is insufficient however, it switches to using fats.
  Monosaccharides contain one sugar unit, disaccharides two, and polysaccharides three or more. Monosaccharides include glucose, fructose and galactose. Disaccharides include sucrose, lactose, and maltose; purified sucrose, for instance, is used as table sugar. Polysaccharides, which include starch and glycogen, are often referred to as 'complex' carbohydrates because they are typically long multiple-branched chains of sugar units.
  Traditionally, simple carbohydrates were believed to be absorbed quickly, and therefore to raise blood-glucose levels more rapidly than complex carbohydrates. This, however, is not accurate. Some simple carbohydrates (e.g., fructose) follow different metabolic pathways (e.g., fructolysis) that result in only a partial catabolism to glucose, while, in essence, many complex carbohydrates may be digested at the same rate as simple carbohydrates.  The World Health Organization (WHO) recommends that added sugars should represent no more than 10% of total energy intake.
  The most common plant carbohydrate nutrient, starch, varies in its absorption. Gelatinized starch (starch heated for a few minutes in the presence of water) is far more digestible than plain starch, and starch which has been divided into fine particles is also more absorbable during digestion. The increased effort and decreased availability reduces the available energy from starchy foods substantially and can be seen experimentally in rats and anecdotally in humans. Additionally, up to a third of dietary starch may be unavailable due to mechanical or chemical difficulty.
caption: Grain products: rich sources of complex and simple carbohydrates
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