Vitamin B12 and homocysteine share an important relationship. Deficiencies in vitamin B12 are associated with high blood levels of homocysteine levels. Homocysteine is associated with increased risk of stroke, heart attack and the development of atherosclerosis. Therefore, understanding this relationship could help you prevent cardiovascular events in the future.
Homocysteine Metabolism
Homocysteine is an amino acid that is synthesized in the body and broken down by protein enzymes. These enzymes breakdown homocysteine to cysteine and contribute the production of methionine and require vitamin B12 to function. A person with the condition homocystinuria has a disruption in the metabolism of homocysteine and has a chronically high level of homocysteine in his urine; homocystinemia refers to a condition of chronically elevated blood levels of homocysteine.
Vitamin B12 Effects on Homocysteine
A deficiency in vitamin B12 is associated with elevated homocysteine in the blood. However, vitamin B12 supplementation to replenish stores doesn't reverse the damage caused by elevated homocysteine except in people with homocystinuria. The water soluble vitamins pyroxidine, or B6, and folate also need to be supplemented to decrease cardiovascular event in this patient population.
Vitamin B12, Homocysteine and Bone
Fracture risk increases in the elderly with high homocysteine levels.This risk can be lowered by treatment with vitamin B12 and folate. Homocysteine decreases collagen formation and doesn't directly affect bone structure.
Vitamin B12 Deficiency and Homocysteine
Since replacing vitamin B12 doesn't decrease cardiovascular events, high homocysteine may only serve as an indicator for vitamin B12 deficiency. It's possible that high levels of homocysteine may have already irreparably damaged the cardiovascular system by the time vitamin B12 deficiency is detected and subsequently replaced. Maintaining an adequate intake of vitamin B12 throughout life may be the best way to prevent damage caused by elevated homocysteine.
References
- "Journal of the American Medical Association"; Effects of Homocysteine-Lowering With Folic Acid Plus Vitamin B12 Versus Placebo on Mortality and Major Morbidity in Myocardial Infarction Survivors; June 2010
- "Journal of Nutritional Health and Aging"; Biomarkers of Cobalamin Deficiency and its Application; W. Chatthanawaree; March 2011
- "New England Journal of Medicine"; Homocysteine Lowering With Folic Acid and B Vitamins in Vascular Disease; E. Lonn, et al;
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