Betaine is a naturally derived ingredient that is added to skin and hair care products due to its ability to provide benefits such as increased hydration, skin protection, improved hair strength and silkiness, and enhanced texture of formulations.
Betaine is a natural substance that was discovered in the 19th century in sugar beets (Beta vulgaris). Since then, it has been found at high concentrations in several other organisms, including wheat bran, wheat germ, spinach, beets, microorganisms, and aquatic invertebrates. The chemical structure of betaine resembles glycine with three extra methyl groups, which is why betaine is also called trimethylglycine. In addition to dietary intake, betaine can be synthesized from the combination of choline and the amino acid glycine in the body.
Betaine has several important biological functions. For example, as a methyl group donor, betaine participates in methylation, an essential biochemical process that aids in liver function, detoxification, and cellular functioning within the body. It’s most crucial role is to help the body process fats. Betaine is also an essential osmoprotectant, primarily in the kidneys, liver, and brain. Interestingly, large amounts of betaine can accumulate in cells without disrupting cell function. This role of betaine protects cells, proteins, and enzymes under osmotic stress.
The function of betaine depends on how it is produced. Synthetically produced betaine, such as cocamidopropyl betaine, functions as a surfactant. Natural betaine, which is obtained from the process of making sugar out of sugar beets by chromatography of the molasses, functions as an osmolyte.
Osmolytes are compounds affecting osmosis, the process in which a solvent moves across a selectively permeable membrane separating two solutions of different concentrations. In the body, a state of hyperosmosis can cause water to flow out of the cells, leading to a reduction in cell volume. These effects are detrimental to cell survival. As an osmolyte, the structure of betaine allows it to attract water and help to maintain cell water balance. This function of betaine is particularly important for skin cells that are dehydrated or exposed to UV radiation. Furthermore, the ability of betaine to increase skin hydration has been shown to have an anti-wrinkle effect.
Research has found that betaine can also improve tight junction integrity. Tight junctions are protein complexes that prevent leakage of solutes and water between the cells. Tight junctions have been suggested to contribute in the prevention of penetration of harmful substances, such as allergens, pollutants, etc. into the skin. Additionally, tight junctions aid in preventing water loss through the skin. Therefore, by improving tight junction integrity, betaine increases the hydration status of the skin and also protects the skin from harmful environmental substances.
The high water retention capability of betaine makes it an ideal ingredient for hair care products. One study found that the increase of water retention into the hair treated with betaine was 40% by average, compared to hair treated with glycerol at only 6%. Furthermore, when betaine is added to hair conditioners it has been shown to improve the hair feel and the ease of wet/dry combing. Overall, the addition of betaine to hair care products gives the hair more strength and hydration, as well as makes the hair shiny and more elastic.
Betaine also functions as a texture enhancer in cosmetics and personal care products. It is known to provide a silky feel to skin care preparations without causing tackiness. Betaine also has the ability to increase the swelling speed of some hydrophilic thickeners and enhancers their thickening power by 20% on average. Additionally, when betaine is added to formulations containing surfactants, it has been shown to increase foam volume and reduce irritation potential of surfactants. This property of betaine is ideal for shampoos, especially when used to formulate a delicate, easy-rinse baby shampoo that contains a low amount of surfactants.
The Cosmetic Ingredient Review (CIR) Expert Panel has not assessed the safety of natural betaine, only synthetic betaines (i.e., cocamidopropyl betaine (CAPB) and related amidopropyl betaines). However, naturally derived betaine is considered to be a stable and nontoxic substance.
References: Front Immunol. 2018; 9: 1070, Cosmetics & Toiletries Magazine, 2000, 115(12), 47-54, Dr. Axe, “What is Betaine? Benefits, Signs of Deficiency and Food Sources”, DuPont Industrial Biosciences, “Natural Betaine in Personal Care”, 2012.