HOMOCYSTEINE
Homocysteine is an amino acid that forms in our body as a result of breakdown of dietary protein. It is also an intermediate molecule in the synthesis of the amino acid cysteine from methionine, (another amino acid). The main role of methionine in the body is to provide methyl groups for metabolic processes to occur. When methionine loses a methyl group it becomes homocysteine. In order for homocysteine to be converted back into methionine, it must receive a methyl group from either folic acid (vitamin B9), or vitamin B6. Vitamin Â12 is needed as a co-factor for this reaction to occur.
Homocysteine can be measured in our bloodstream; a high reading usually indicates we do not get enough vitamins B6, Â12 or folic acid in our diet. These vitamins are found in high amounts in fresh fruit and vegetables, as well as animal protein such as red meat, eggs and fish. Betaine is another nutrient helpful in keeping homocysteine low; it is found in high amounts in eggs. Diets high in processed foods are often lacking these nutrients. Having high blood levels of homocysteine is thought to be a major risk factor for heart disease, and several other diseases.
The inner lining of our arteries is called the endothelium. In healthy arteries the endothelial cells form a continuous protective layer, regulating which substances can pass from the bloodstream into the deeper artery wall. If our endothelial cells are injured and inflamed, it makes the artery lining more permeable, allowing molecules to enter the artery wall. Homocysteine has an abrasive action; it scrapes the inner lining of our blood vessels. People with high homocysteine levels have greater damage to the lining of their arteries and more atherosclerotic plaques. High levels of homocysteine also seem to activate platelets and increase the tendency for clots to form. A study published in the Journal of the American Medical Association showed that men with the highest homocysteine levels are three times more likely to have a heart attack, regardless of their cholesterol or triglyceride levels. High blood homocysteine levels have also been strongly linked with the following diseases: Alzheimer’s disease, osteoporosis, depression, diabetes, multiple sclerosis, rheumatoid arthritis and birth defects.
What Causes Elevated Homocysteine?
• Inadequate intake of folic acid, vitamin B6 or vitamin B12 in your diet, or malabsorption of these.
• Genetics. Some people have a genetic defect which affects their ability to absorb and use folic acid. These people need higher amounts of folic acid than a normal diet can provide, and they are best off taking a supplement.
• Stress. Adrenaline and noradrenaline are stress hormones and their metabolism requires methylation. This increases our need for vitamins B6, Â12 and folic acid. If our intake is inadequate, homocysteine will build up.
• Coffee consumption. The more coffee we drink, the higher our homocysteine tends to be.
• Oral contraceptive use. This is because oral contraceptives deplete the body of vitamin B6 and folic acid. This may be one reason why oral contraceptives can increase the risk of heart disease.
• Impaired kidney function.
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