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Elevated Homocysteine harmful for eyes

Homocysteine is an amino acid in the blood. It appears to be a nerve and vessel toxin, promoting mortality, cardiovascular disease (CVD), stroke, Alzheimer's disease, birth defects, recurrent pregnancy loss, and eye disorders.

It has been recently reported by the researchers at the Medical College of Georgia. that high levels of an amino acid called homocysteine could harm the eyes. They suspect that homocysteine - already believed to contribute to heart attack, stroke and dementia - likely helps cause retinal damage and vision loss. Preliminary evidence suggests that elevated homocysteine levels damage the extensive blood vessel and neuronal network of the retina.

Normal serum homocysteine levels are from 2.2 to 13.2 µmol/l. Levels of homocysteine in typical Western populations are about 12 µmol/l. Although this is "normal," it is not necessarily healthy.

Keeping homocysteine at levels associated with lower rates of disease requires both adequate B12 and folate (also known as folic acid) status. Low vitamin B6 status can also cause elevated homocysteine in some people.

Lifestyle factors which increase homocysteine levels include:

•Diet - high alcohol intake and coffee consumption reduce the absorption of vitamins

•Smoking

•Lack of physical exercise and excessive stress

•Obesity

•Drugs and certain diseases also influence homocysteine metabolism.

If several of these factors are combined, their impact may be substantial.

Tied to folic acid

Methionine is an essential amino acid obtained from protein in the diet. Some methionine is turned into homocysteine. The body turns much of this homocysteine back into methionine with the help of vitamin B12. If someone is B12-deficient, homocysteine levels will increase because this reaction cannot take place.

This is a problem for many people, because they don't eat enough folate-rich fruits, vegetables and grains. People need about 400 micrograms of folate daily. Pregnant women as well as those trying to become pregnant need at least double that.

Plant Sources of Folate
Food    amount                µg
cooked lentils                 1/2 Cup  179
cooked black beans        1/2 Cup  128
romaine lettuce              1 1/2 Cup  114
orange juice                  1 Cup   109
cooked spinach              1/2 Cup  103
canned refried beans      1/2 Cup  106
cooked garbanzo beans  1/2 Cup  80
cooked navy beans        1/2 Cup  82
cooked broccoli              1 Cup   78
sunflower seeds             1/4 Cup  76
cooked pinto beans        1/2 Cup  72
cooked kidney beans      1/2 Cup  63

RDA for folate is 400 µg for people over age 13.

Folate and vitamin B12 convert homocysteine to methionine, an amino acid that plays a vital role in protein synthesis. When this conversion fails to occur, elevated homocysteine levels interfere with the folding and structure of collagen, a component of bone, tissue and blood vessel walls.

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