What is it?
An emulsifier and skin-softening ingredient made by joining stearic acid, a saturated 18-carbon fatty acid, to polyglycerin-3, a short chain averaging three glycerin units. It helps oil and water form stable creams and lotions. The “-3” counts glycerin units; it is not a PEG and is not made with ethylene oxide. A self-emulsifying grade, labeled polyglyceryl-3 stearate SE, also contains some sodium or potassium stearate.
Key information
- Polyglyceryl-3 stearate is made from glycerin and stearic acid; it is not ethoxylated.
- The CIR Expert Panel concluded in 2016 that polyglyceryl fatty acid esters are safe as used when formulated to be non-irritating.
- In 2016 it was reported in 17 cosmetic products at concentrations up to 0.61 percent.
- Polyglycerol esters of fatty acids are permitted food emulsifiers in the U.S. and the EU (E 475).
More information
To make it, glycerin is first heated with an alkaline catalyst so that its molecules link together and release water, forming polyglycerin. The number in the name is the average number of glycerin units per chain. The polyglycerin is then esterified with stearic acid. Polyglycerins, like PEGs, are polyethers, but they are built from glycerin rather than ethylene oxide, so polyglyceryl esters are not ethoxylated. Other production routes using epichlorohydrin or glycidol exist, and EFSA recommended maximum limits for those two chemicals in the food additive; in 2022 it reported that suppliers of food-grade polyglycerol confirmed they do not use epichlorohydrin.
The Cosmetic Ingredient Review (CIR) Expert Panel reviewed 274 polyglyceryl fatty acid esters in 2016 and concluded they are safe as used when formulated to be non-irritating, because some members of the group, such as certain isostearates and oleates, irritated rabbit skin. Among its closer relatives, 10 percent polyglyceryl-10 stearate did not irritate human skin, and feeding studies with polyglyceryl stearate produced no remarkable effects.
As food emulsifiers, polyglycerol esters of fatty acids are permitted in the U.S. and, as E 475, in the EU. The Joint FAO/WHO Expert Committee on Food Additives set an acceptable daily intake of 0 to 25 mg/kg of body weight for esters averaging up to three glycerol units. EFSA’s 2017 re-evaluation found they are almost entirely broken down into polyglycerols and fatty acids in the gut and concluded there was no safety concern at reported uses.
On labels, look for “polyglyceryl-3 stearate” or “polyglyceryl-3 stearate SE.”
Sources: Cosmetic Ingredient Review: Safety assessment of polyglyceryl fatty acid esters as used in cosmetics (2016); EFSA: Re-evaluation of polyglycerol esters of fatty acids (E 475) as a food additive (2017); EFSA: Follow-up of the re-evaluation of polyglycerol esters of fatty acids (E 475) (2022)
