The essential amino acid L-methionine is synthesized in the body as part of the metabolism of proteins, and in turn is an intermediate step in the creation of cysteine, carnitine and taurine - all critical to eye health. Its conversion to cysteine requires adequate levels of B vitamins.

Vision Health Role

As a part of certain cell functions, the amino acid L-methionine contributes a molecule to the process, and is "repaid" that molecule from vitamin B12 or folic acid. However, when the body is deficient in those nutrients this remethylation does not occur and homocysteine remains. Over time high levels of homocysteine build up and been connected to a number of vision and health conditions.

  • High levels of homocysteine have been tied to macular degeneration and other retinal conditions.
  • Possible connection between high homocysteine levels and glaucoma, diabetic retinopathy and optic neuropathy
  • Needed for the body's synthesis of taurine, carnitine and cysteine.
  • Helps remove heavy metals and toxins from the body

Eye disorders. There are connections between high levels of homocysteine and advanced macular degeneration,1, 2 other retinal conditions, and photoreceptor problems.3 It is linked to glaucoma,4 diabetic retinopathy,5 and optic neuropathy.6

Food sources. This nutrient is found in egg whites, fish, poultry, and crustaceans. In smaller quantities it is found in seaweed, sesame seed, and cottage cheese.

Health Role

As described above, inadequate reconversion of homocysteine to methionine causes elevated homocysteine levels which are connected to heart disease, depression, dementia, risk of fetal problems in mothers with high levels of homocysteine, osteoporosis, stroke, and other conditions. For more information, see the article on homocysteine.


1. Ghosh, S., Saha, M., Das, D. (2013). A study on plasma homocysteine level in age-related macular degeneration. Nepal J Ophthalmol, Jul-Dec;5(2):195-200.
2. Huang, P., Wang, F., Sah, B.K., Jiang, J., Ni, Z., et al. (2015). Homocysteine and the risk of age-related macular degeneration: a systematic review and meta-analysis. Sci Rep, Jul;21;5:10585.
3. Ganapathy, P.S., Perry, R.L., Tawfik, A., Smith, R.M., Perry, E., et al. (2011). Homocysteine-mediated modulation of mitochondrial dynamics in retinal ganglion cells. Invest Ophthalmol Vis Sci, Jul 25;52(8):5551-8.
4. Ghanem, A.A., Mady, S.M., El awady, H.E., Arafa, L.F. (2012). Homocysteine and hydroxyproline levels in patients with primary open-angle glaucoma. Eye Res, Aug;37(8):712-8.
5. Xu, C., Wu, Y., Liu, G., Liu, X., Wang, F., Yu, J. (2014). Relationship between homocysteine level and diabetic retinopathy: a systematic review and meta-analysis. Diagn Pathol, Sep 26;9:167.
6. Stanger, O., Weger, M., Obeid, R., Temmel, W., Meinitzer, A., et al. (2005). Impairment of homocysteine metabolism in patients with retinal vascular occlusion and non-arteritic ischemic optic neuropathy. Clin Chem Lab Med, 2005;43(10):1020-5.

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