Betaine

Overview

Betaine — sometimes labeled “trimethylglycine” or “TMG” — is a naturally occurring zwitterionic amino acid derivative. In nature it is found in sugar beets, spinach, and wheat bran; in cosmetic supply it is extracted from sugar-beet molasses as a co-product of sugar production. The cosmetic-grade material is a fine white crystalline powder, water-soluble, and very stable.

It is one of the gentler humectants in the toolkit — soothing, mild, and especially well-suited to sensitive skin. It is also one of the older skincare ingredients, used in formulations for over a century, but it has come back into fashion as a foil to high-glycerin formulations because of how it improves the skin feel.

Important: do not confuse cosmetic betaine (the humectant) with cocamidopropyl betaine or coco betaine (amphoteric surfactants used in shampoos and body washes). Different molecules, different jobs. This entry is about the simple humectant betaine only.

What it does in a formula

Primary roles:

• Humectant — attracts and retains moisture; comparable hydration to glycerin per gram
• Skin soother — has osmoprotective properties at the cellular level, helping cells resist the dehydration of low-humidity environments
• Tackiness reducer — when added alongside glycerin, it reduces the sticky/tacky feel without sacrificing moisture

Secondary roles: mild anti-inflammatory effect, useful in sensitive-skin formulations and post-shave or post-procedure products; pairs well with proteins (keratin, silk) in hair conditioners to soften the protein feel.

How to use

Add to the water phase. Heat-stable up to boiling. Goes in heated water phase or cool-down without issue.

Usage range:

• Face creams and lotions: 2-5%
• Body lotions: 2-4%
• Hair conditioners: 1-3%
• Shampoos: 1-2% (where it softens the surfactant feel)
• Sensitive-skin formulations: 2-3%
• As a glycerin foil: 1-3% alongside 3-5% glycerin to reduce tackiness

pH range: stable across the full cosmetic pH range. Plays well with all common actives.

It is fully water-miscible and dissolves quickly when sprinkled into water with stirring. No need to pre-dissolve in a glycol.

Best for / Worst for

Best for: sensitive-skin lotions, after-sun and post-procedure gels, baby skincare, gentle facial cleansers, hair conditioners (softens the protein/cationic feel), barrier-repair formulas, dry-climate moisturizers (the osmoprotective effect helps in low humidity).

Worst for: cost-sensitive bulk formulations (glycerin is cheaper for the same hydration), anhydrous balms (water-soluble only), formulas where you want a noticeable “glycerin pull” effect.

Common pitfalls

Confusing it with cocamidopropyl betaine. They share a name root but are different molecules with different jobs. Cosmetic betaine is a humectant; cocamidopropyl betaine is a foaming surfactant.

Expecting dramatic results. Betaine is a quiet supporting ingredient. It does not produce visible “wow” effects — it makes the formula feel better and supports the work of the headline actives.

Using it as the only humectant. Betaine alone gives mild hydration. Combine with glycerin, propanediol, or sodium PCA for full moisture coverage.

Buying food-grade in bulk. Food-grade betaine is fine for cosmetic use chemically, but it may contain trace impurities that affect skin feel. Cosmetic-grade is purified to a cleaner profile.

Substitutes

• Glycerin for stronger humectant pull, more tackiness, cheaper.
• Propanediol for similar silky feel with solvent properties.
• Sodium PCA for stronger humectant per gram and a skin-mimicking profile.
• Sodium Lactate for similar humectant effect with mild keratolytic properties (avoid in photosensitive routines).
• Hyaluronic acid / sodium hyaluronate for film-forming hydration — different mechanism, complementary.