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A Simplified Treatment Approach Based on the Glutathione Depletion-Methylation Cycle Block Pathogenesis Hypothesis for Chronic Fatigue Syndrome (CFS)
What is Glutathione, and What Does it do?
Glutathione is technically a tripeptide, which can be thought of as being like a very small protein, as it is made up of only three amino acids (while proteins are made up of many more). It is present naturally in every cell of the body, as well as in the blood, the bile and the fluid lining the lungs. The liver is normally the main producer of glutathione in the body. Glutathione plays many important roles in the body. Probably the best known are its protection against oxidative stress produced by oxidizing free radicals and other reactive oxygen species, its support for the immune system, and its role in removing a variety of toxic substances from the body.
When glutathione becomes somewhat depleted, as it does in many cases of CFS, its normal functions are simply not performed well. Many of the symptoms of CFS as well as observed abnormal results on specialized lab tests can be traced directly to glutathione depletion, as I described in an earlier AACFS poster paper in 2004. It can be found on Cort Johnson’s website
As I noted in that paper, while direct efforts to build glutathione are helpful to many PWCs, for most they provide only temporary improvement and do not result in permanent restoration of glutathione levels or a cure for CFS. I suspected that a vicious circle mechanism must be involved in holding down the glutathione levels in CFS.
Then, later in 2004, an important paper was published involving research into autism by S. Jill James and her coworkers: “Metabolic biomarkers of increased oxidative stress and impaired methylation capacity in children with autism”
(Am J Clin Nutr. 2004 Dec;80(6):1611-7). The study they reported showed that glutathione is depleted also in autism, and that this depletion is associated with a block in what is known as the methylation cycle (or methionine cycle).
THE METHYLATION CYCLE
“What is the Methylation Cycle, and What Does it do?”
The methylation cycle is part of the basic biochemistry of the body, and is believed to operate in every cell. This cycle includes the amino acid methionine as well as S-adenosylmethionine (SAMe, used as a supplement by some PWCs), S-adenosylhomocysteine, and homocysteine. Some homocysteine is converted back to methionine, thus completing the cycle. There are two parallel pathways from homocysteine to methionine. They are the methionine synthase pathway and the BHMT (betaine homocysteine methionine transferase) pathway. The methylation cycle is directly linked to the folate metabolism and to the transsulfuration pathway.
The methylation cycle performs many vital roles in the body. First, by means of SAMe, it supplies methyl (CH3) groups to many different biochemical reactions. Some of them produce substances such as coenzyme Q-10 and carnitine, which have been found to be depleted in many PWCs. Methylation also plays an important role in “silencing” certain DNA to prevent its expression, and in producing myelin for the brain and nervous system.
The methylation cycle also controls the body’s response to oxidative stress, by governing how much homocysteine is diverted into the transsulfuration pathway, which contributes to determining the rate of synthesis of glutathione.
A third important role of the methylation cycle is to control the overall sulfur metabolism of the body. In this role, besides controlling glutathione synthesis, it exerts control over synthesis of several other important substances, including cysteine, taurine and sulfate.
When the methylation cycle is blocked at the enzyme methionine synthase, these important roles are not carried out properly. In addition, a methylation cycle block necessarily causes a block in the folate metabolism, to which it is intimately linked, and this interferes with synthesis of new DNA and RNA, among other important effects.
Two of the most significant effects of a methylation cycle block are that neither the immune system nor the detox system can operate properly. If the methylation cycle remains blocked for an extended period of time, infections and toxins can be expected to build up in the body.