Sorbitol

Sorbitol, also known as glucitol, is a sugar alcohol that the body metabolises slowly. It is obtained by reduction of glucose changing the ether group to an additional hydroxyl group hence the name sugar alcohol.

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Use as a sweetener

Sorbitol is used in various cough syrups and "sugar-free" mints and is usually listed under the inactive ingredients. Too much sorbitol (from 10 to 50g, or more for adults) can cause gastro-intestinal problems.^[1]

Sorbitol is a sugar substitute often used in diet foods (including diet drinks and ice cream) and sugar-free chewing gum. It also occurs naturally in many stone fruits and berries from trees of the genus Sorbus^[2]. Sorbitol is also referred to as a nutritive sweetener because it provides dietary energy: 2.6 kilocalories (11 kilojoules) per gram versus the average 4 kilocalories (17 kJ) of sugar and starch, while retaining 60% of the sweetness.^{[citation needed]} As a food additive it has an E number E420, categorized as a sweetener, emulsifier and humectant.

Use as a laxative

Sorbitol can be used as a non-stimulant laxative as either an oral suspension or suppository. The drug works by drawing water into the large intestine, thereby stimulating bowel movements.^[3] Sorbitol has been determined safe to use in the elderly although it is by no means recommended. ^[4]

Clinical significance

Ingesting large amounts of sorbitol can lead to some abdominal pain, gas, and mild to severe diarrhea. Sorbitol can also aggravate irritable bowel syndrome and fructose malabsorption.^{[citation needed]}

Even in the absence of dietary sorbitol, cells also produce sorbitol naturally. When too much sorbitol is produced inside cells, it can cause damage.^[5] Diabetic retinopathy and neuropathy may be related to excess sorbitol in the cells of the eyes and nerves. The source of this sorbitol in diabetics is excess glucose, which goes through the polyol pathway.^{[citation needed]}

Other uses

Sorbitol is often used in modern cosmetics as a humectant and thickener. Some transparent gels can only be made with sorbitol as it has a refractive index sufficiently high for transparent formulations. It is also used as a humectant in some cigarettes.^{[citation needed]}

Sorbitol is used as a cryoprotectant additive (mixed with sucrose and sodium polyphosphates) in the manufacture of surimi, a highly refined, uncooked fish paste most commonly produced from Alaska (or walleye) pollock (Theragra chalcogramma).^{[citation needed]}

Furthermore, Sorbitol, combined with Kayexalate, helps the body rid itself of excess potassium ions in a hyperkalaemic state. The Kayexalate exchanges sodium ions for potassium ions in the bowel, while sorbitol helps to eliminate it.^{[citation needed]}

Sorbitol when combined with potassium nitrate has found some success as an amateur solid rocket fuel.^[6]

Sorbitol is identified as a potential key chemical intermediate ^[7] from biomass resources. Complete reduction of sorbitol opens the way to alkanes such as hexane which can be used as a biofuel. Sorbitol itself provides much of the hydrogen required for the transformation.

19 C₆O₆H₁₄ → 13 C₆H₁₄ + 36 CO₂ + 42 H₂O

The above chemical reaction is exothermic and 1.5 mole of sorbitol generates 1 mole of hexane. When hydrogen is co-fed, no carbon dioxide production takes place.

See also

• Mannitol
• Xylitol