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Homocysteine: evidence for a causal relationship with cardiovascular disease
1Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA. scottch@mail.med.upenn.edu
Insights
Elevated homocysteine is linked to vascular disease. Supplementation with folic acid and B vitamins may help normalize levels in at-risk patients.
Area of Science:
- Biochemistry
- Vascular Biology
- Nutritional Science
Background:
- Elevated plasma homocysteine is a risk factor for vascular disease and thrombosis.
- Genetic defects in homocysteine metabolism lead to premature atherosclerosis and thromboembolism in children.
- Heterozygous defects in adults cause delayed onset of vascular disease.
Purpose of the Study:
- To review the association between homocysteine levels and vascular pathology.
- To discuss the mechanisms by which homocysteine contributes to vascular damage.
- To highlight the potential role of vitamin supplementation in managing hyperhomocysteinemia.
Main Methods:
- Literature review of epidemiological studies and biochemical mechanisms.
- Analysis of the impact of homocysteine on vascular endothelium, smooth muscle cells, platelets, and coagulation.
- Evaluation of the efficacy of B vitamins (folic acid, B6, B12) in homocysteine metabolism.
Main Results:
- Homocysteine damages vascular endothelium, promotes smooth muscle proliferation, activates platelets, and enhances lipid peroxidation.
- Epidemiologic studies consistently link high homocysteine to coronary artery disease, cerebrovascular disease, and thromboembolism.
- Folic acid, vitamin B6, and vitamin B12 can normalize homocysteine levels in the majority of individuals.
Conclusions:
- Hyperhomocysteinemia is a significant risk factor for vascular disease.
- Vitamin supplementation offers a potential therapeutic strategy for patients with elevated homocysteine.
- Further randomized trials are needed to confirm the efficacy of homocysteine reduction in preventing vascular events.
Abstract:
Elevated plasma homocysteine levels are associated with vascular disease and thrombosis. Premature atherosclerosis and thromboembolism are seen in children who are homozygotes for defects in enzymes responsible for the metabolism of homocysteine. Adults with heterozygous defects have less marked elevations of homocysteine, and onset of atherosclerosis and vascular disease are delayed into the fourth and fifth decade of life. Homocysteine can damage vascular endothelium, cause proliferation of vascular smooth muscle, activate platelets, promote lipid peroxidation, and activate the coagulation cascade. Epidemiologic studies have linked elevations in plasma homocysteine with coronary artery disease, cerebrovascular disease, and thromboembolism. Folic acid, in combination with vitamins B6 and B12, can normalize homocysteine levels in most patients. Although randomized trials assessing the efficacy of homocysteine reduction have yet to be completed, treatment with vitamin supplementation should be considered in all patients at risk for vascular disease.