E422

Glycerol (Glycerine)

Last reviewed: 8 May 2026

The moisture-retainer in UK soft cookies and gluten-free bread — and the vegan / halal sourcing question

What glycerol actually is

E422 is glycerol — also written "glycerine" on UK labels and "glycerin" on US ones. The chemistry is the same molecule: a small three-carbon polyol with three hydroxyl (-OH) groups, formula C₃H₈O₃, also known as 1,2,3-propanetriol. In its purified form it's a clear, viscous, sweet-tasting liquid that's strongly hygroscopic — meaning it pulls water out of the air and binds it tightly. That single property is the reason it's so widely used in food.

Glycerol isn't an exotic addition. It's the chemical backbone of every triglyceride, which is the structural form of all dietary fats. When the body digests fat, lipase enzymes split each triglyceride into three fatty acids and one glycerol molecule. So trace glycerol naturally exists in any food that contains fat, and the body produces and metabolises it constantly. The "E422" you see on a label is concentrated, isolated glycerol added in measurable quantities for a specific job — not a foreign substance, but not the same thing as the trace amount that comes free with fat either.

On the tongue, glycerol reads as roughly 60–75% as sweet as sucrose, with around 4.3 kcal per gram. It has a lower glycaemic impact than table sugar, but it isn't calorie-free and isn't metabolically inert.

What it does in food

Glycerol earns its place on UK ingredient lists because one molecule does five jobs at once. Manufacturers reach for it when a product needs to stay soft, stay moist, stay scoopable from the freezer, or carry a flavour that won't dissolve in water on its own.

Humectant. The headline use. Glycerol grabs water and holds it inside the food matrix instead of letting it migrate to the surface and evaporate. That's what keeps a soft chewy cookie soft three weeks after baking, what stops fudge crystallising, and what gives marshmallows their give.
Texture and mouthfeel. In low-fat or sugar-reduced products, glycerol contributes the chew, body and slight slipperiness that fat or sugar would otherwise provide.
Freezing-point depression. Added to ice cream and frozen desserts, glycerol lowers the freezing point of the water phase and keeps ice crystals small. The result is a softer, scoopable texture straight from a cold freezer rather than a brick.
Sweetener. In sugar-free chocolate, sugar-free sweets and reduced-sugar formulations, glycerol contributes sweetness and bulk — usually paired with maltitol or another polyol to hit the right sugar-replacement profile.
Solvent and carrier. Many flavour compounds and food colours don't dissolve well in water. Glycerol does dissolve them, so it's used as the liquid vehicle for flavour extracts and colour preparations that then disperse into the finished product.
Bulking agent. When sugar is removed from a recipe, the formulation loses physical mass as well as sweetness. Glycerol fills part of that gap.

Where it turns up on UK labels

If a product needs to stay soft, moist or scoopable without going stale, glycerol is often doing the work. The most common UK appearances:

Soft chewy cookies — supermarket bakery cookies and own-label "American-style" soft cookies almost always list it.
Fudge, marshmallows, jelly sweets and fondant — any confectionery where the texture is supposed to stay yielding rather than set hard.
Gluten-free breads and rolls — without gluten holding the crumb together, GF loaves stale fast. Glycerol is one of the standard anti-staling tools.
Sugar-free and reduced-sugar chocolate — usually combined with maltitol, isomalt or another polyol.
Low-sugar jams and jellies — to add body and bind water that sugar would otherwise have bound.
Cake icings and fondant — keeps the surface from hardening.
Some chewing gum — softens the gum base and retains moisture.
Energy bars and protein bars — humectant plus mild sweetness; bars are one of the higher-dose food sources of glycerol.
Frozen desserts and some ice creams — for scoopability.
Some wines — small amounts as a mouthfeel modifier; rare on UK shelves.
Pharmaceutical preparations — cough syrups and oral suspensions use glycerol as a vehicle. Outside the food remit, but worth knowing if you're tracking total intake.

On the label it appears as "E422", "glycerol", "glycerine", "humectant: glycerol" or "sweetener: glycerol" depending on the role it's playing in that product.

The three sourcing pathways — and why UK labels don't tell you which

This is where E422 gets interesting, and where UK labels stop helping. The same molecule can be made three different ways, and the source matters for vegans, vegetarians and halal/kosher consumers — but the label gives you no way to tell which pathway your bar of chocolate or pack of cookies used.

Animal fat (tallow or lard). The traditional source. Glycerol falls out as a by-product of soap-making — when animal fat is saponified, fatty acids form the soap and glycerol is recovered from the residue. Tallow-derived glycerol is not vegan and is unlikely to meet halal or kosher requirements unless the product carries a specific certification.
Vegetable oil (palm, coconut, soy, rapeseed). Now the dominant global source. Vegetable-oil-derived glycerol is vegan-suitable. Halal and kosher status depends on certification of the source oil — palm and coconut are typically straightforward, but the certification is per-product, not automatic.
Biotech / fermentation. Glycerol can be produced by microbial fermentation of glucose. Vegan, generally compatible with most halal and kosher requirements. Less common commercially because it costs more than the vegetable-oil route.

UK labelling does not require source disclosure. "E422", "glycerol" or "glycerine" on its own gives you no information about which of the three pathways made the molecule in your product. If sourcing matters to you — vegan, vegetarian, halal or kosher — the practical route is to look for a separate vegan logo, vegetarian logo or relevant certification mark, or to contact the manufacturer directly. Most large UK manufacturers have moved to vegetable-oil-derived glycerol because of cost and supply, but "most" is not "all", and a missing logo is not the same as a confirmation either way. This is a real information-gap on UK labels rather than something we can resolve from the ingredient list alone.

Laxative effect at high doses

Glycerol shares one property with the better-known polyols (sorbitol, mannitol, maltitol): in large single doses, it can draw water osmotically into the small intestine and the colon, which produces loose stools or diarrhoea. The threshold is meaningfully higher than for sorbitol — published figures put it around 25–30 grams in a single dose for adults — because glycerol is mostly absorbed and metabolised in the body, whereas sorbitol is largely fermented in the colon.

At food-additive levels in cookies, ice cream or jam, the dose per serving is well below that threshold. The places where intake can creep up are protein bars, energy bars and concentrated supplements or pharmaceutical preparations, where a single bar can contain several grams of glycerol and a stack of two or three bars in a session can approach the looser-stool zone for a sensitive individual. People with IBS or other GI sensitivities may notice symptoms earlier.

Glycerol and athletes

For background context: endurance athletes have used concentrated glycerol drinks before hot-weather events as a hyper-hydration aid — sometimes called "glycerol loading". The idea is that glycerol expands the body's fluid compartment by retaining water, which may help in long, hot races. The World Anti-Doping Agency listed glycerol as a prohibited masking agent from 2010 to 2018, then removed it from the prohibited list when subsequent evidence indicated it didn't reliably mask other substances. We're stating this as published context, not as a suggestion to use glycerol for any purpose.

Diabetic and glycaemic angle

Glycerol has a lower glycaemic impact than sucrose — it doesn't spike blood glucose the way table sugar does — but it isn't zero-calorie and it isn't metabolically inert. The body converts glycerol into glucose via the liver (gluconeogenesis), so it does still contribute to blood-sugar load, just less sharply. It's worth noting that "sugar-free" products that lean on glycerol plus maltitol still carry calories and can still affect blood glucose, especially in larger portions. We're not in a position to give individual dietary advice; the underlying facts are the calories and the glycaemic profile, and the rest is between an individual and their GP, dietitian or diabetes team.

Regulatory status

EFSA (UK / EU): the European Food Safety Authority re-evaluated glycerol in 2017 and concluded the acceptable daily intake should be set at quantum satis — meaning no numerical ADI is specified, with use permitted at the level needed to achieve the technological effect. The 2017 opinion did not raise an ADI cap at typical food-additive use levels.

FDA (US): Generally Recognized As Safe (GRAS).

UK / EU labelling: declared on the ingredient list as "E422", "glycerol", "glycerine", "humectant: glycerol" or "sweetener: glycerol" depending on its function in the product. Source (animal, vegetable, fermentation) is not required to be disclosed.

Vegan, vegetarian, halal and kosher — short version

The molecule itself can be vegan, vegetarian, halal and kosher, or it can be none of those, depending on which of the three pathways above produced it for that specific product. The label won't tell you. If the sourcing matters to you, the practical signals are:

A separate vegan or vegetarian logo on the pack.
A halal or kosher certification mark from a recognised body.
Manufacturer confirmation in writing if you want to be sure.

Absence of a logo is not the same as confirmation either way — most UK manufacturers have moved to vegetable-oil-sourced glycerol, but "most" leaves a real gap for anyone who needs certainty.