Evidence supporting the use of: L-cysteine
For the health condition: Skin Care (general)

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Synopsis

Source of validity: Scientific
Rating (out of 5): 2

L-cysteine is an amino acid that plays a significant role in the synthesis of glutathione, one of the body's most important antioxidants. In the context of skin care, L-cysteine is believed to support skin health primarily due to its antioxidant properties and its involvement in the biosynthesis of keratin, a key structural protein in skin, hair, and nails. Some studies suggest that antioxidants like L-cysteine may help protect the skin from oxidative stress caused by UV radiation, pollution, and other environmental factors, which can contribute to premature aging and skin damage.

There is also evidence that L-cysteine may promote skin healing and regeneration. Limited clinical studies have explored oral or topical L-cysteine for conditions like melasma and hyperpigmentation, showing some benefit in reducing pigmentation when combined with other agents. However, the data are not robust, and most studies are small or preliminary. The cosmetic industry sometimes includes L-cysteine in formulations targeting skin lightening or general skin health, but often in combination with other compounds.

Overall, while there is some scientific rationale and early evidence supporting L-cysteine’s use in skin care, the clinical evidence is limited and not conclusive. Therefore, its use for general skin care is best described as having a modest scientific basis, with stronger evidence needed from larger, well-designed human trials to confirm its efficacy and optimal application.

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