Homocysteine may also affect eyes

Augusta, Ga. -- Homocysteine, an amino acid linked to heart attack, stroke and dementia, may also be a player in retinal damage and vision loss, a U.S. researcher says.

Homocysteine levels rise when folic acid levels drop, a problem for many whose diets are poor in folate-rich fruits, tomatoes, vegetables and grains, study leader Dr. Sylvia Smith of the Medical College of Georgia, explains.

Smith exposed layers of retina to high levels of homocysteine and found the retina "terribly disrupted."

Folate and vitamin B12 convert homocysteine to methionine, an amino acid essential to protein synthesis. Without the conversion, rising homocysteine levels interfere with the folding and structure of collagen, a component of bone, tissue and the basement membrane of blood vessel walls, Smith says.

"At any point in your life, too much homocysteine can be problematic, whether you are talking about pregnant women, cardiovascular disease or dementia," Smith says in a statement. "If homocysteine is not converted into methionine or cysteine -- by vitamin B6 -- to aid protein synthesis, it can do something bad."

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