Abstract:
The recent pandemic has energized research spotlighting chronic fatigue disorders. The similarities between Long COVID (LC) and Chronic Fatigue Syndrome (CFS), often accompanied by postural orthostatic tachycardia syndrome (POTS) are striking.
Furthermore, the majority afflicted with LC and CFS may be those with methylenetetrahydrofolate reductase (MTHFR) polymorphisms, present in the majority of Americans and characterized by hypomethylation. Elevated homocysteine (Hcy) and depressed B9 and B12 may be links. Speculation about an association between these laboratory analytes and MTHFR abnormalities has been previously reported (Regland et al., 2015).
The absence of a blood-brain barrier (BBB) in CNS circumventricular organs (CVOs) that control autonomic and neuroendocrine functions, problematic in LC, CFS, POTS, and MTHFR, is provocative. Diffusion of CNS Hcy is associated with brain fog, cognitive impairment, and dementia. This provides a distinct link between MTHFR variants and the fog of LC, CFS, and POTS.
Small intestine bacterial overgrowth (SIBO), present in about 17% of Americans, is linked to POTS, mast cell activation syndrome (MCAS), and Ehlers Danlos syndrome (EDS). All exhibit histamine intolerance and female predominance. This may be due to hypomethylation and/or intestinal diamine oxidase (DAO) deficiency.
Metabolism of monoamines and histamine requires methylation. Specific CNS nuclei in CVOs may also provide insight to the POTS paradox. The similar gut microbiomes of LC/CFS (and vitamin D deficiency) may via CVOs trigger an imbalance in glutamate/GABA neurotransmission that translates to neuroendocrine and baroreflex dysfunction. Homozygosity for the MTHFR 677T allele can facilitate hypermethylation via an alternative “rescue” riboflavin pathway triggered by significant Hcy increase.
Hypermethylation predominates in Long Covid. The primary problem in these syndromes is compromised mitochondrial function due to oxidative stress induced by an antioxidant shortfall.
Victims are also frequently deficient in 25(OH)D3 (the storage form of vitamin D), magnesium, and B vitamins, consumed by the persistent chronic inflammatory state. Estrogen increases histamine, norepinephrine, and bradykinin (BKN), which may in part explain the brain fog and its predilection for females.
Source: Patrick W Chambers. Long COVID, POTS, CFS and MTHFR: Linked by Biochemistry and Nutrition. Journal of Orthomolecular Medicine. 38. https://www.researchgate.net/publication/373073968_Long_Covid_POTS_CFS_and_MTHFR_Linked_by_Biochemistry_and_Nutrition#fullTextFileContent (Full text)