From the Research
Cysteine plays a crucial role in maintaining hair health as it is a key component of keratin, the primary protein that forms hair structure, and its supplementation has been shown to increase hair density and improve overall hair appearance, as demonstrated in a recent study 1. This sulfur-containing amino acid creates disulfide bonds between protein chains, giving hair its strength, elasticity, and overall integrity. When hair has adequate cysteine, it appears stronger, more resilient, and less prone to breakage. Some key points to consider:
- Cysteine contributes to hair health both through dietary intake and topical applications.
- Foods rich in cysteine include eggs, poultry, dairy, legumes, and seeds, which can support hair growth from within.
- Topical hair products containing N-acetyl cysteine (NAC) or L-cysteine may help strengthen damaged hair by reinforcing these crucial disulfide bonds.
- Additionally, cysteine acts as an antioxidant, protecting hair follicles from oxidative stress and environmental damage, as shown in a study evaluating the antioxidant effects of human hair protein extracts 2.
- For those experiencing hair thinning or brittleness, ensuring adequate cysteine intake through diet or supplements (typically 500-1000mg daily) may support improved hair structure, though results vary by individual and underlying causes of hair issues. It is also worth noting that the reduction mechanism of L-cysteine on keratin fibers has been investigated, and it was found that L-cysteine can decrease the reaction rate of disulfide bonds in hair 3. Furthermore, a combination of low dosage retinol and L-cystine has been shown to improve alopecia of the diffuse type following long-term oral administration 4. However, the most recent and highest quality study 1 suggests that oral supplementation with L-cystine can increase hair density and improve overall hair appearance, making it a promising treatment option for hair loss.