Arginine is an amino acid that is used in cosmetics and personal care products to protect the skin from free radicals, increase skin hydration, and boost collagen production.
In 1886, arginine was first isolated from lupin and pumpkin seedlings by the German chemist Ernst Schulze. It is an alpha-amino acid that is used in the biosynthesis of proteins. In addition to building protein, arginine releases nitric oxide in the blood. Nitric oxide dilates blood vessels in the bloodstream, which may help certain circulatory conditions. Arginine also plays an important role in cell division, wound healing, immune function, the release of hormones, and the production of growth hormone.
Arginine can be found in animal products such as meat, dairy, and eggs, as well as several plant sources including grains, beans, and nuts. Arginine is also available as an oral supplement. Most healthy people do not need to supplement with arginine because it is a component of all protein-containing foods and can also be synthesized by the body.
In cosmetics and personal care products, arginine helps to protect the skin from free radicals, increase skin hydration, and boost collagen production.
Arginine has been shown to have antioxidant activity. Antioxidants work by neutralizing free radicals, the unstable molecules that contribute to the formation of premature wrinkles and fine lines on the skin. Free radicals damage important cellular components, such as the cell membrane, DNA, and cellular proteins like collagen. Damaged collagen is a major factor that contributes to the appearance of aged skin. Therefore, by using topical antioxidants like arginine, the skin will be better protected from free radicals.
Another function of arginine in skin care products is to increase skin hydration by acting as a humectant. A humectant is a hygroscopic substance that often has a molecular structure with several hydrophilic (water-loving) groups. This structure allows humectants to attract and retain the moisture in the air nearby via absorption, drawing the water vapor into or beneath the surface. Arginine also helps to synthesize components of the skin’s Natural Moisturizing Factor (NMF), such as ceramides, cholesterol, urea, and glycosaminoglycans. Together with the naturally-occurring lipids in skin, NMF components work to keep skin’s surface intact, supple, and hydrated.
One study evaluated the effects of topical 2.5% arginine hydrochloride ointment on transepidermal water loss, urea content in the stratum corneum, and overall skin hydration. The results of this study indicated that topical arginine increased urea content and improved skin hydration.
Lastly, arginine is often used in anti-aging skin care products because of its ability to increase collagen production. When arginine is metabolized to urea and ornithine by the enzyme arginase-1, L-proline is generated. L-proline is an amino acid that is a substrate for collagen synthesis. Increasing the amount of collagen in the skin improves skin firmness and decreases signs of aging. In addition to these anti-aging effects, the ability of arginine to increase collagen production also helps to speed wound healing.
The safety of arginine and the other alpha amino acids has been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel. Its maximum concentration for use in a formulation is 18%. Due to the normal presence of arginine in the body and its use as a direct food additive approved by the FDA, the Panel focused their review on dermal irritation and sensitization data. Dermal data on products containing arginine indicated that this ingredient is not a dermal irritant or sensitizer. Thus, the Panel concluded that arginine and the other alpha amino acids were safe as used in cosmetics and personal care products.
References: Wikipedia “Arginine”, Medical News Today “L-arginine: Potential benefits, side effects, and risks” 2017, Ceramiracle “Arginine” 2017, Wound Repair Regen 2006 Jul-Aug;14(4):376-86, Cosmetics Info “Arginine”