Most people who have ME/CFS also have genetic mutations in their genes involved in methylation, namely MTRR, MTR and perhaps MTHFR. For these people, just going by lab diagnostics for B12 is useless at best, and misleading at worst. Their B12 needs are extremely high.
Vol. 128 No. 12, December 1993
Neurologic Degeneration Associated With Nitrous Oxide Anesthesia in Patients With Vitamin B12 Deficiency
Teresa S. Flippo, MD; Walter D. Holder, Jr, MD
Arch Surg. 1993;128(12):1391-1395.
Vitamin B12 [cobalamin] is an integral component of two biochemical reactions in man: the conversion of L-methylmalonylcoenzyme A into succinyl coenzyme A and the formation of methionine by methylation of homocysteine. The transmethylation reactionis essential to DNA synthesis and to the maintenance of the myelin sheath by the methylation of myelin basic protein. Active vitamin B12 contains cobalt in its reduced form (Co+). Nitrous oxide produces irreversible oxidation to the Co++ and Co+++ forms that renders vitamin B12 inactive. Five cases (four from the literature and one new case) are presented in which patients unsuspected of having vitamin B12 deficiency developed subacute combined degeneration of the spinal cord following nitrous oxide anesthesia. Patients with vitamin B12 deficiency are exceedingly sensitive to neurologic deterioration following nitrous oxide anesthesia. If unrecognized, the neurologic deterioration becomes irreversible and may result in death.
(Arch Surg. 1993;128:1391-1395)