Mannitol is the alcohol form of mannose. It occurs naturally in pineapples, olives, asparagus, sweet potatoes, and carrots. Mannitol is extracted from seaweed for use in food manufacturing. It is sometimes used as a sweetener in dietetic products.
Mannitol is a nutritive sweetener (compare to non-nutritive sweeteners such as aspartame and saccharin which provide no nutrients or calories), stabilizer, humectant and bulking agent in foods and supplements. It can be derived from the Manna plant or from seaweed, however, for commercial use, it is manufactured via a catalytic hydrogenation process.
Mannitol is one of several carbohydrates classified as a sugar alcohol or polyols. Xylitol and sorbitol are examples of other sugar alcohols. The chemical structure of mannitol allows it to be absorbed more slowly by the body than regular sugars. Therefore, it has a smaller impact on blood insulin levels, making it and other sugar alcohols useful for diabetic foods. On the other hand, because it slowly absorbed, excessive consumption may have a laxative effect, similar to certain high--fiber foods. Because of this, products containing mannitol must include a laxative warning on the label if the mannitol content in a serving exceeds 20g. Mannitol does not promote tooth decay. It is approximately 72% as sweet as sugar (sucrose) and is reported to have a cool, sweet taste.
Mannitol is a 6-carbon sugar that does not undergo metabolism. It is not absorbed in the GI tract thus, must be given IV. It does not cross an intact blood brain barrier (BBB). It does not enter cells and is cleared by glomerular filtration. The glomeruli filter mannitol which does not get reabsorbed from renal tubules; therefore, mannitol increases the osmolarity of renal tubular fluid and prevents reabsorption of water. Sodium, the renal tubular fluid, is diluted and less is reabsorbed. Mannitol works osmotically to create diuresis. Mannitol works by creating an osmotic gradient. Side effects result from its osmotic effect. Acutely, mannitol increases intravascular volume which can precipitate pulmonary edema and/or congestive heart failure, especially in patient with poor cardiac function. Hypovolemia can occur along with hypotension. Nephrotoxins and prolonged renal ischemia can damage renal tubules so that they become permeable to mannitol and its osmotic effect is lost. Finally, venous thrombosis is a rare event and tissue necrosis is unlikely with extravasation of mannitol (the opposite is true for urea). Mannitol also increases plasma osmolarity and draws fluid from intracellular to extracellular spaces relieving increased ICP and increased ocular pressure. If the BBB is damaged, worsened elevations in ICP could occur as mannitol enters the brain tissue and causes an osmotic gradient into the tissue.
Synonyms: 1,2,3,4,5,6-hexanehexol, mannite, manna sugar
Molecular formula: HOCH2(CHOH)4CH2OH
CAS No: 69-65-8