E421 (Mannitol, D-Mannitol) is a natural alcohol found in the form of sugar alcohols in the human body where it is metabolically inert. In vegetables and fruit (olive and persimmon) and also in some mushrooms and seaweed.

It occurs as a white crystalline powder with a sweet taste. Soluble in water, slightly soluble in ethanol, almost soluble in ether.

What it is used for and where

Medical

• in surgery to reduce intracranial pressure and facilitate retraction of the brain in case of ruptured aneurysm and for intraocular pressure
• for the prevention of early acute renal failure
• a good diuretic
• as a research tool in cell biological studies to control osmolarity and as a bacterial culture agent. For the determination of boron in chemical analysis.
• has both hydrating and antioxidant properties, making it an ideal excipient for drugs.

 Food

Low-calorie sweetener in food products for diabetic patients and bodybuilding foods. Viscosity reducer for maltose.  

Labelled with the number E421 in the European food additives list assweetener, emulsifier and stabilising agent.

Cosmetics

Binder agent. Ingredient that is used in cosmetic, food and pharmaceutical products as an anti-caking agent with the function of making the product in which it is incorporated silky, compact and homogenous. The binder, either natural such as mucilage, gums and starches or chemical, may be in the form of a powder or liquid.

Fragrance. It plays a decisive and important role in the formulation of cosmetic products as it provides the possibility of enhancing, masking or adding fragrance to the final product, increasing its marketability.  The consumer always expects to find a pleasant or distinctive scent in a cosmetic product.

Humectant. Hygroscopic compound used to minimise water loss in the skin and to prevent it from drying out by facilitating faster and greater absorption of water into the stratum corneum of the epidermis.  The epidermis is the most superficial of the three layers that make up human skin (epidermis, dermis and hypodermis) and is the layer that maintains hydration in all three layers. In turn, the epidermis is composed of five layers: horny, the most superficial, granular, spinous, shiny, and basal. Humectants have the ability to retain the water they attract from the air in the stratum corneum and have the function of moisturising the skin. They are best used before emollients, which are oil-based.

Moisturizing. This ingredient is responsible for preventing the evaporation of moisture from the skin and improving cellular activity. When exposed to cold or hot air currents, the skin absorbs water from its inner layer to compensate for the evaporated water. If the draught phenomenon persists, the stratum corneum is dry and, if at all, damaged.

Skin conditioning agent. It is the mainstay of topical skin treatment as it has the function of restoring, increasing or improving skin tolerance to external factors, including melanocyte tolerance. The most important function of the conditioning agent is to prevent skin dehydration, but the subject is rather complex and involves emollients and humectants that can be added in the formulation.

Other uses

Plastics industry to produce artificial glycerine resins and rosin esters.

Explosives and as nitrified mannitol to produce detonators.

The most relevant studies on this ingredient have been selected with a summary of their contents:

"Mannitol, studies"

Typical commercial product characteristics Mannitol

• Molecular Formula    C₆H₁₄O₆
• Molecular Weight  182.172 g/mol
• Exact Mass   182.079041
• CAS   69-65-8  87-78-5
• EC Number: 200-711-8  201-770-2
• UNII: 3OWL53L36A
• PubChem Substance ID 329823038
• MDL number MFCD00064287
• Beilstein Registry Number 1721898
• DSSTox Substance ID  DTXSID1023235
• IUPAC  (2R,3R,4R,5R)-hexane-1,2,3,4,5,6-hexol
• InChI=1S/C6H14O6/c7-1-3(9)5(11)6(12)4(10)2-8/h3-12H,1-2H2/t3-,4-,5-,6-/m1/s1  
• InChl Key      FBPFZTCFMRRESA-KVTDHHQDSA-N
• SMILES   C(C(C(C(C(CO)O)O)O)O)O
• ChEBI  16899
• NCI   C625  
• RXCUI   6628   
• RTECS   OP2060000

Synonyms:

• Mannite
• D-mannitol
• Osmitrol
• Mannitol, D-
• Manna sugar
• Invenex
• Osmofundin
• Osmosal
• Cordycepic acid
• Mannidex 16700
• Mannit