Cysteine is a required amino acid in glutathione production. Cysteine, consumed as n-acetylcysteine, helps your retina stay healthy by supporting synthesis of glutathione along with glutamine and glycine. Cysteine is the only amino acid that is not commonly found in foods. The supportive role of cysteine helps prevent primary open-angle or normal tension glaucoma and macular degeneration.

Cataract. Cysteine is essential in order to maintain a healthy lens to focus vision, to support macular health, and to prevent damage to the optic nerve. Cysteine combines with another amino acid, tryptophan, to protect the lens from UV radiation.1 In fact, there is a special biochemical "pathway" to regulate cysteine uptake in the lens.2

Food sources. Good sources of cysteine include soybeans, sunflower seeds, legumes, kamut, oats, cheese, eggs, beef, lamb, chicken, pork, and fish.


1. Schafheimer, J., Wang, Z., Schey, K., King, J. (2014). Tyrosine/cysteine cluster sensitizing human γD-crystallin to ultraviolet radiation-induced photo aggregation in vitro. Biochemistry, Feb 18;53(6):979-90.
2. Lim, J.C., Lam, L., Li. B., Donaldson, P.J. (2013). Molecular identification and cellular localization of a potential transport system involved in cystine/cysteine uptake in human lenses. Exp Eye Res, Nov;116:219-26.

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