Glucidi

Glucidi, or carbohydrates, are a broad class of organic compounds composed mainly of carbon, hydrogen, and oxygen, typically with the formula (CH2O)n. They range from simple sugars to large polysaccharides and are a major energy source for many organisms. The simplest glucidi are monosaccharides such as glucose and fructose; disaccharides such as sucrose and lactose are formed by glycosidic bonds between monosaccharides; polysaccharides such as starch, glycogen, and cellulose are long chains of sugar units.

Carbohydrates play diverse biological roles. As energy sources, they fuel cellular processes through pathways such as glycolysis and respiration, yielding about 4 kilocalories per gram. Some glucidi serve structural functions, notably cellulose in plant cell walls and chitin in arthropod exoskeletons. They also contribute to cellular components and signaling, with ribose and deoxyribose forming the backbone of nucleotides and glycoproteins involving sugar moieties in various functions.

Dietary carbohydrates include naturally occurring sugars in fruits, vegetables, and grains, as well as starches and dietary fiber. Digestible starch and disaccharides are broken down to monosaccharides and absorbed, primarily as glucose, which can be stored as glycogen in liver and muscle or used to produce energy. Dietary fiber, composed of non-digestible polysaccharides, affects gut motility, fermentation processes, and metabolic health; soluble and insoluble fibers have distinct effects.

Carbohydrate classification commonly distinguishes simple from complex glucidi, and reducing from non-reducing sugars, with the structure of glycosidic bonds (alpha or beta) influencing digestibility. In nutrition, guidelines emphasize adequate, mostly complex carbohydrate intake with sufficient fiber and limited added sugars, while recognizing the role of carbohydrates as a primary energy source.

The term glucidi is often used in Italian or older European contexts; in English, the preferred term is carbohydrates or glucides.