Betaine

Betaine is a small, water-loving molecule that living cells use to hold their water balance when conditions turn dry or salty. In skincare it is used as a humectant, an ingredient that attracts and holds water, with a soft, non-sticky feel.

At a glance

• Evidence level A. Published research on the ingredient itself.
• What it is. Trimethylglycine, a derivative of the amino acid glycine, found widely in plants and animals.
• What it does. Holds water. Skin feels hydrated without a tacky finish.
• Caution. Well tolerated in the literature. A different ingredient from the surfactant cocamidopropyl betaine.

What it is

Betaine takes its name from the sugar beet, Beta vulgaris, where it was first identified and from which commercial betaine is commonly recovered. Chemically it is glycine carrying three methyl groups, which is why it is also called trimethylglycine.

In biology, betaine is an osmolyte. When the water around a cell becomes scarce or salty, the cell accumulates small molecules such as betaine to hold its volume without disturbing its proteins. Plants, marine organisms and human cells, including the cells of the outer skin, all use this strategy.

A naming trap. Cocamidopropyl betaine, a common cleansing surfactant, shares the word but is a different ingredient with a different job. On an ingredient list, "Betaine" on its own means the humectant.

What it does in skincare

As a humectant, betaine binds water in the upper layers of skin. Formulators also choose it for texture: it can reduce the sticky feel that high levels of glycerin leave, so it often appears alongside other humectants rather than replacing them.

A humectant draws water; a moisturizer seals it in. Follow a humectant serum with a moisturizer, especially in dry air. More on routines for this: hydration and barrier.

Evidence

The studies below describe the ingredient itself.

Burg and Ferraris reviewed how intracellular organic osmolytes, betaine among them, protect cells under osmotic stress. Warskulat and colleagues showed that normal human keratinocytes, the main cells of the epidermis, take up betaine and other osmolytes to maintain their balance under dry or hyperosmotic conditions.

Craig reviewed betaine in human nutrition, including its sources and metabolism. That work establishes what the molecule is and how the body handles it.

The skin-specific clinical literature on betaine as a single cosmetic ingredient is limited. Its use as a humectant rests on its chemistry and on its established biological role.

Use and caution

• Betaine is rarely associated with irritation in the literature and suits most skin types, including skin that reacts easily. See sensitivity and recovery.
• Apply humectant serums to slightly damp skin, then follow with a moisturizer.
• As with any new product, patch test first if your skin is reactive.

In Vegalab products

The Hydrating NanoSerum sealed vial set lists betaine among its water-binding ingredients, with sodium PCA, trehalose, glycereth-26, butylene glycol and ectoin.

• Hydrating NanoSerum, Sealed Vial Set

Where an ingredient sits in a list, and what that tells you: how to read an ingredient list.

Related ingredients

• Sodium PCA, a component of skin's natural moisturizing factor
• Trehalose, a water-holding sugar
• Ectoin, another osmolyte, from extremophile bacteria
• All entries: ingredient library

References

1. Burg MB, Ferraris JD. Intracellular organic osmolytes: function and regulation. J Biol Chem. 2008;283(12):7309-7313.
2. Warskulat U, Reinen A, Grether-Beck S, Krutmann J, Häussinger D. The osmolyte strategy of normal human keratinocytes in maintaining cell homeostasis. J Invest Dermatol. 2004;123(3):516-521.
3. Craig SAS. Betaine in human nutrition. Am J Clin Nutr. 2004;80(3):539-549.