Glycerin Absorption and Metabolism
Glycerin is chemically classified as a sugar alcohol, but it is more similar to sugars: it is readily absorbed and is probably converted into glucose in the human body and it provides 4.3 kilocalories of energy per gram [2,3]. Glycerin is not one of the FODMAPs (fermentable oligo-, di- and monosaccharides and polyols), because it is well absorbed in the small intestine and does not pass to the large intestine where it would be fermented by intestinal bacteria.
Glycerin is often mentioned as a sweetener with a low glycemic index, but there are no reliable sources to confirm this.
Types of Edible Glycerin
Vegetable glycerin is made from vegetable oils (palm oil, palm stearin, palm kernel oil, coconut oil, soybean oil) during production of soap or biodiesel.
Animal glycerin is a natural byproduct of animal fats (such as beef tallow) during production of soap.
Synthetic glycerin is produced from cane or corn syrup sugar, or propylene (a petroleum derivative).
Glycerin as a Food Additive
Food-grade glycerin may be added as a humectant (wetting agent), thickener, solvent or sweetener to dairy products (cream), canned goods, confections, fondant, processed fruits, jams, energy bars and other foods. The source of glycerin (animal or vegetable oil, corn syrup, petroleum) used in a food product is usually not revealed on the food labels.
Other Glycerin Uses
- An emulsifier in pills, syrups, toothpastes, mouth washes, fluoride gels, tobacco, etc.
- Anhydrous glycerin is used in fluoride gels, and is approved as an over-the-counter (OTC) anti-caries drug by US Food and Drug Administration (FDA) [14].
- A lubricant, enema or laxative, as a suppository is used to treat constipation.
- Oral glycerin, as a drug, is used to lower high pressure within the eye (glaucoma).
- Intravenous glycerin can be used to treat brain swelling (cerebral edema) [7].
- Glycerin may be used as a skin or hair moisturizer.
