Homocysteine is an amino acid by-product of methionine metabolism. Elevated plasma levels of homocysteine are now recognized independent risk factors for coronary artery disease, cerebrovascular disease and peripheral vascular disease. The quantitative increase in risk for developing these diseases is approximately 1.5 times for an increase in total plasma homocysteine level of 5mmoles (Beresford & Boushey, 2001).
There is a possible causal relationship between increased homocysteine level and increased risk of CVD in that homocysteine may induce oxidation of LDL particles and also alteration of the endothelial lining, making it more prone to accumulation of fatty plaques.
Using Vitamins To Reduce Homocysteine Levels
The accumulation of homocysteine in normal individuals is now linked to the deficiency of the B vitamins, folic acid, vitamin B12 and vitamin B6. As the Figure below shows, all of these are ultimately associated in methionine metabolism. Numerous studies have now shown that supplementation of these compounds with the addition of betaine is consistently able to lower homocysteine levels in the majority of individuals. Folate is the most important of these nutrients and when supplemented alone is able to lower homocysteine. However, the difference is greater and more consistent when complemented with the other nutrients.
Key Enzymes:
- N-5-methyltetrahydrofolate: homocysteine methyltransferase
(methionine synthase)
- Betaine: homocysteine methyltransferase
- Methylene-tetrahydrofolate reductase (MTHFR)
- Cystathionine b-synthase
- Gamma-cystathionase
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