L-cysteine amino acid could be the secret to winning your fight for thicker hair growth. It’s an amino acid that is getting increasing attention in the hair loss industry. There’s mounting scientific evidence behind amino acids like L-cysteine and its cousin, L-methionine. And cysteine, specifically, is showing up more and more these days in hair care products and hair supplements. Get all your questions answered about L-cysteine hair growth and what L-cysteine is good for.
What Is L-Cysteine?
L-cysteine is a conditionally essential amino acid, which is the building block of proteins. Conditionally essential means that it can be made by our bodies but only in small amounts and only in healthy adults under good conditions.
What Are the Benefits of L-Cysteine for Hair?
L-cysteine amino acid is one of the main building blocks of the keratin, a fibrous protein that makes up the structure of skin, nails and hair. Without enough L-cysteine to maintain keratin structures, your hair will weaken and be prone to breakage.
Hair consists of three layers, the cuticle, the cortex and the medulla. The cortex is the middle, and most prominent, layer of the hair strand, making up around 80% of its structure. The cortex contains keratin molecules bundled together into a fibrous structure that contains about 75% L-cysteine, which is what gives hair its strength.
Not only that, but L-cysteine is one of the few amino acids that can create what are called disulfide bonds, which hold keratin together and even help hair retain moisture.
Finally, L-cysteine is essential in helping the body to metabolize certain nutrients, including biotin. As you probably know, biotin (vitamin B7) is an important nutrient for hair growth.
Scientific Research on L-Cysteine
A 2000 study in Germany found that a combination of L-cysteine, pantothenic acid and millet seed extract improved hair growth in women with diffuse hair loss. After three months, these women had a significant increase in the number of hair strands, compared with participants who were given a placebo.
Another study in 2015 examined the effects of marine protein-based supplements on telogen effluvium hair loss emphasized that L-cysteine as a critical component of this type of protein. Furthermore, it cited previous studies where L-cysteine helped improve the tensile strength of hair as well as hair growth in otherwise healthy women who are experiencing excessive shedding and hair loss.
The Best Foods with L-Cysteine
Under healthy conditions, the body is able to manufacture L-cysteine from the amino acid L-methionine, which is an essential acid that you must get from food. Foods like soybeans, beef, lamb, sunflower seeds, cheese, oats and chick peas are all rich in L-cysteine.
How Much L-Cysteine Should I Take?
The recommended daily allowance (RDA) for adults of L-methionine, when combined with L-cysteine, is 14 mg. per Kg. of body weight per day (about 6 mg./lb. of body weight per day). But some sources estimate the recommended L-cysteine dosage for hair growth at about 200-500 mg. per day.
Infants and elderly people with metabolic disorders may be unable to manufacture L-cysteine on their alone and may need oral supplements.
For other healthy adults, if you just want to boost your intake, you can get your L-cysteine levels in balance by taking L-cysteine hair supplements or eating good sources of protein as part of a healthy diet.
Topical Applications of L-Cysteine in Hair Care Products
Some hair care and styling products like hair oils and shampoos have added L-cysteine too. Topical L-cysteine in these forms may help maintain the keratin and disulfide bond structure in your hair. Cysteine hair treatments like these can help maintain the hair strength, moisture levels and elasticity for stronger hair with less breakage.