Category: sweetener
Aliases: E421, D-Mannitol, Mannite, Osmitrol, Manna sugar, Cordycepic acid
Six-carbon sugar alcohol (hexitol), the reduced form of mannose, non-glycemic and non-cariogenic. Orally it is poorly absorbed — lacking an active intestinal transporter, it crosses the mucosa slowly by passive diffusion, so the bulk reaches the colon where it draws water osmotically (laxative) and is fermented by gut flora to short-chain fatty acids and gas, yielding only ~1.6 kcal/g; the absorbed fraction is largely excreted unchanged in urine, not metabolised by hexokinase. Given intravenously it is a distinct clinical agent: confined to extracellular fluid, freely filtered at the glomerulus and essentially non-reabsorbed, it acts as an osmotic diuretic and raises plasma osmolality to pull water from brain and ocular tissue, lowering intracranial and intraocular pressure before renal clearance largely intact.
IV: 1.186h