Test Overview of Homocysteine
Homocysteine is a general marker of metabolic imbalance, and elevated levels are an independent cardiovascular risk factor.
The important point about homocysteine is that it participates in the very important
S-adenosylmethionine Cycle (SAM or SAMe) that makes S-adenosylmethionine
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S-adenosylmethionine in turn is then consumed by many biochemical reactions that transfer a methyl group. A variety of enzymes that have "methyltransferase" in their names, such as COMT (catechol-O-methyltransferase), ASMT (acetylserotonin-N-methyltransferase), and hydroxyindole-O-methyltransferase (HIOMT) all depend on the SAM cycle.
COMT acts on neurotransmitters such as dopamine and epinephrine, and ASMT helps convert the neurotransmitter serotonin to melatonin.
In order for the SAM cycle to transfer one methyl group (called methylation), the SAM cycle
requires vitamin B12, one molecule of ATP and one molecule of 5-methyltetrahydrofolate,
which is derived from vitamin B9 (which is also called folic acid or folate)
via the tetrahydrofolate cycle, which also consumes one molecule of ATP and
two molecules of NADPH
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Both vitamin B12 and vitamin B9 are "essential nutrients," which means that they cannot be made by our body, but must be obtained from food. Deficiency of either of these two vitamins can cause a build-up of homocysteine.
ATP is mostly made in our mitochondria, so anything that hampers mitochondrial function can hamper the SAM cycle and the tetrahydrofolate cycle, and upset neurotransmitter balance and disrupt many other biochemical processes, including DNA maintenance.