All About B12: High Serum B12 and Which Form of B12 Is Best ?
*This article is not medical advice. Before starting on any health related regimen, seek the advice of your Primary Care Physician or an M.D.
What is with High Serum B12 in Chronic Illness – Even for Folks Who Don't Take B12 ?
Plus... Neurodegeneration and Blue Zone Diets
There are numerous reports from individuals of the chronic illness community, particularly those in Facebook support groups, who experience high serum B12 levels in the midst of experiencing significant health challenges.
Greg R. Jones's work on paradoxical B12 deficiency highlights the belief that elevated serum B12 can paradoxically indicate a B12 deficiency. This may develop due to a variety of underlying causes and, rather than simply increasing B12 intake (which can lead to further complications), addressing the root issue is crucial.
You may find this article interesting if you:
Want to understand the relationship between having both chronic illness and elevated serum B12 levels.
Want to understand the potential mechanism for paradoxical elevated B12 levels in the face of chronic illness.
Want to understand to relationship between cobalt, glutathione, and serum B12 levels
Want to understand the relationship between tydroxycobalamin form of B12 and Nitric Oxide (NO)
Potential Mechanisms for the Paradoxical Development of Elevated B12 Levels in Chronic Illness
Potential mechanisms include:
Increased Oxidative Stress
Increased oxidative stress may lead to insufficient glutathione activity, which in turn results in reduced B12 processing.
"Recent findings in diseases associated with oxidative stress have revealed that intracellular oxidative stress results in local functional B12 deficiency. Insufficient intracellular processing of B12 due to oxidative stress has been reported in diabetes mellitus or in Alzheimer’s disease, where it has been postulated to be a significant pathophysiological factor. Intracellular reduction of the central cobalt atom is essential for the formation of the metabolically active forms of B12. This process requires reduced glutathione and the hydroquinone form of flavin adenine dinucleotide (FADH2); it is therefore compromised by oxidative stress. In such conditions treatment with glutathione and/or vitamin C, a key physiological regenerator of intracellular glutathione, may provide therapeutic benefit. This warrants further investigation." [1]
Elevated Nitric Oxide levels
Elevated nitric oxide levels are commonly encountered in many people diagnosed with ME/CFS, as are high levels of peroxynitrite, a compound formed from the combination of nitric oxide and superoxide.
Elevated nitric oxide can degrade B12 by oxidizing the cobalt ion at B12’s center resulting in un-usable B12 [11].
Supplementation with the hydroxycobalamin form of B12 has a history of being helpful for some people with ME/CFS.
Hydroxycobalamin has the unique characteristic of lowering nitric oxide production by inhibiting NOS1, and NOS2 [12].
Genetic Mutations
Mutations in the MMACHC and MMADHC genes cause a deficiency in the cofactors necessary for proper functioning of the enzymes needed for cobalamin absorption. Thus, Cobalamin C (CblC) and D (ColD) cofactor deficiency leads to developmental delays and other serious health consequences.
"Pathways for tailoring and processing vitamins into active cofactor forms exist in mammals that are unable to synthesize these cofactors de novo. A prerequisite for intracellular tailoring of alkyl cobalamins entering from the circulation is removal of the alkyl group to generate an intermediate that can subsequently be converted into the active cofactor forms. MMACHC, a cytosolic cobalamin trafficking chaperone, has been shown recently to catalyze a reductive decyanation reaction when it encounters cyanocobalamin. In this study, we demonstrate that this versatile protein catalyzes an entirely different chemical reaction with alkyl cobalamins using the thiolate of glutathione for nucleophilic displacement to generate cob(I)alamin and the corresponding glutathione thioether. Biologically relevant thiols, e.g. cysteine and homocysteine, cannot substitute for glutathione. The catalytic turnover numbers for the dealkylation of methylcobalamin and 5′-deoxyadenosylcobalamin by MMACHC are 11.7 ± 0.2 and 0.174 ± 0.006 h−1 at 20 °C, respectively. This glutathione transferase activity of MMACHC is reminiscent of the methyltransferase chemistry catalyzed by the vitamin B12-dependent methionine synthase and is impaired in the cblC group of inborn errors of cobalamin disorders." [2]
"Human CblC has been shown to interact with CblD, a protein involved in B12 trafficking, albeit its function is not understood. Stable interaction between CblC and CblD required the presence of alkylcobalamins and GSH (Glutathione)." [3]
"Methylmalonic aciduria and homocystinuria type C protein (MMACHC) is required by the body to metabolize cobalamin (Cbl). Due to its complex structure and cofactor forms, Cbl passes through an extensive series of absorptive and processing steps before being delivered to mitochondrial methyl malonyl-CoA mutase and cytosolic methionine synthase. Depending on the cofactor attached, MMACHC performs either flavin-dependent reductive decyanation or glutathione (GSH)-dependent dealkylation. The alkyl groups of Cbl have to be removed in the presence of GSH to produce intermediates that can later be converted into active cofactor forms. Pathogenic mutations in the GSH binding site, such as R161Q (rs rs121918243 ), R161G (rs ), R206P (rs ), R206W (rs ), and R206Q (rs ), have been reported to cause Cbl diseases. The impact of these variations on MMACHC’s structure and how it affects GSH and Cbl binding at the molecular level is poorly understood. To better understand the molecular basis of this interaction, mutant structures involving the MMACHC-MeCbl-GSH complex were generated using in silico site-directed point mutations and explored using molecular dynamics (MD) simulations. The results revealed that mutations in the key arginine residues disrupt GSH binding by breaking the interactions and reducing the free energy of binding of GSH. Specifically, variations at position 206 appeared to produce weaker GSH binding. The lowered binding affinity for GSH in the variant structures could impact metabolic pathways involving Cbl and its trafficking." [4]. (In case you are wondering, it’s : rs371753672).
"Methylmalonic aciduria and homocystinuria, cblC type (OMIM 277400), is the most common inborn error of vitamin B(12) (cobalamin) metabolism, with about 250 known cases. Affected individuals have developmental, hematological, neurological, metabolic, ophthalmologic and dermatologic clinical findings. Although considered a disease of infancy or childhood, some individuals develop symptoms in adulthood. The cblC locus was mapped to chromosome region 1p by linkage analysis. We refined the chromosomal interval using homozygosity mapping and haplotype analyses and identified the MMACHC gene. In 204 individuals, 42 different mutations were identified, many consistent with a loss of function of the protein product. One mutation, 271dupA, accounted for 40% of all disease alleles. Transduction of wild-type MMACHC into immortalized cblC fibroblast cell lines corrected the cellular phenotype. Molecular modeling predicts that the C-terminal region of the gene product folds similarly to TonB, a bacterial protein involved in energy transduction for cobalamin uptake." [9] 271dupA on MMACHC, rs398124292 [8].
Key Takeaways
Low B2 levels, low glutathione levels, and/or excessive oxidative stress (which depletes glutathione) can make B12 ineffective. This happens when glutathione recycling is blocked (B2 is essential for this), or when there’s an excess of hydrogen peroxide (due to GPX4 or GPX1 mutations) or peroxynitrite (from too much nitric oxide and superoxide, i.e. NOS uncoupling).
High serum B12 is often a sign of low B2, low glutathione, and high oxidative stress (which can also lead to a blocked heme pathway).
The MMACHC gene plays a crucial role in B12 processing, and it relies on sufficient glutathione to function properly.
Excess nitric oxide degrades B12 by oxidizing the cobalt ion at its center [11], rendering it functionally useless, which can lead to high serum B12 that is non-functional.
the hydroxycobalamin form of B12 can inhibit production of nitric oxide by NOS1 and NOS genes [12], thus restoring balance and stopping the recurring disablement of B12. The adeno- and methyl- forms of B12 do not display this same type of effect. Hydroxycobalamin B12 supplementation has a long history in people with ME/CFS as a treatment that helps ease symptoms.
Causes and Consequences
Cobalamin Deficiency
"The causes of cobalamin (B12, Cbl) deficiency are multifactorial. Whether nutritional due to poor dietary intake, or functional due to impairments in absorption or intracellular processing and trafficking events, the major symptoms of Cbl deficiency include megaloblastic anemia, neurological deterioration and in extreme cases, failure to thrive and death. The common biomarkers of Cbl deficiency (hyperhomocysteinemia and methylmalonic acidemia) are extremely valuable diagnostic indicators of the condition, but little is known about the changes that occur at the protein level. A mechanistic explanation bridging the physiological changes associated with functional B12 deficiency with its intracellular processers and carriers is lacking. In this article, we will cover the effects of B12 deficiency in a cblC-disrupted background (also referred to as MMACHC) as a model of functional Cbl deficiency. As will be shown, major protein changes involve the cytoskeleton, the neurological system as well as signaling and detoxification pathways. Supplementation of cultured MMACHC-mutant cells with hydroxocobalamin (HOCbl) failed to restore these variants to the normal phenotype, suggesting that a defective Cbl processing pathway produces irreversible changes at the protein level."[5]
Glutathione Deficiency and Toxic Insults
"Ethanol, arsenic, lead, mercury, aluminum and the vaccine preservative thimerosal are suspected to be etiological factors for neurodegenerative and neurodevelopmental disorders. Autism is a neurodevelopmental disorder characterized by oxidative stress and impaired methylation status, including decreased activity of the folate and vitamin B12-dependent enzyme methionine synthase (MS, known as the MTR gene). MS-mediated conversion of homocysteine to methionine is crucial for neurons and all mammalian cells to sustain normal methylation status, involving more than 100 different reactions. Glutathione (GSH) protects MS from oxidative inactivation by reactive oxygen species, while MS inactivation increases GSH (glutathione) synthesis by augmenting transsulfuration. Utilizing SH-SY5Y cultured human neural cells, we found that a 1 hour pre-incubation of cells with arsenic, lead, mercury, aluminum and thimerosal potently decreased both hydroxocobalamin (OHCbl) and methylcobalamin (MeCbl)-based MS activity, although OHCbl exhibited greater sensitivity than MeCbl. At a concentration of 100 nmol, each of these neurodevelopmental toxins caused a 60–70% reduction of intracellular GSH levels. 22 mM (0.1%) ethanol caused a similar inhibition of OHCbl- and MeCbl-based MS activity and a similar decrease in GSH levels. Our findings suggest that heavy metals and ethanol may contribute to the occurrence of neurodevelopmental disorders such as autism via a mechanism that involves oxidative stress and inhibition of MS activity."[6]
Conclusion
High Serum B12 in Chronic Illness:
High serum B12 can indicate deficiency: Even without B12 supplements, people with chronic illness may have high B12 levels in blood tests, which paradoxically signals a deficiency. This may be linked to issues with how the body processes B12 due to oxidative stress.
Oxidative stress & B12 processing: Conditions like diabetes and Alzheimer's can impair intracellular B12 processing due to oxidative stress, making the vitamin ineffective. Glutathione (a key antioxidant) and vitamin C may help restore proper B12 processing.
Gene MMACHC's role: The MMACHC gene is essential for converting B12 into its active form, but mutations or oxidative stress can disrupt this process, leading to B12 deficiency symptoms.
Excess Nitric Oxide Can degrade B12: NO can oxidize the cobalt ion at the center of the B12 structure [11], disabling B12 resulting in excess unusable B12 in the blood. Hydroxy b12 can inhibit NOS1, and NOS2, lowering nitric oxide.
References:
[1] Supraphysiological vitamin B12 serum concentrations without supplementation: the pitfalls of interpretation C Vollbracht, G P McGregor, and K Kraft. QJM. 2020 Sep; 113(9): 619–620. Published online 2019 June 28. doi: 10.1093/qjmed/hcz164. PMCID: PMC7550708 PMID: 3125136
[2] A Human Vitamin B12 Trafficking Protein Uses Glutathione Transferase Activity for Processing Alkylcobalamins By Jihoe Kim. J Biol Chem. 2009 Nov 27; 284(48): 33418–33424. doi: 10.1074/jbc.M109.057877. PMCID: PMC2785186. PMID: 19801555
[3] Glutathione-dependent One-electron Transfer Reactions Catalyzed by a B12 Trafficking Protein. By Li, et. al. Received for publication, March 20, 2014, and in revised form, April 16, 2014 Published, JBC Papers in Press, April 17, 2014, DOI 10.1074/jbc.M114.567339
[4] Interaction of Glutathione with MMACHC Arginine-Rich Pocket Variants Associated with Cobalamin C Disease: Insights from Molecular Modeling. by Priya Antony. Biomedicines 2023, 11(12), 3217; https://doi.org/10.3390/biomedicines11123217
[5] Proteomics of vitamin B12 processing. By Hannibal, et. al. Published by De Gruyter December 12, 2012. From the journal Clinical Chemistry and Laboratory Medicine. https://doi.org/10.1515/cclm-2012-0568
[6] Neurodevelopmental Toxins Deplete Glutathione and Inhibit Folate and Vitamin B12-Dependent Methionine Synthase Activity: A Link between Oxidative Stress and Autism. By MOSTAFA IBRAHIM-AHMED WALY, RICHARD DETH. The FASEB Journal First published: 01 March 2008 https://doi.org/10.1096/fasebj.22.1_supplement.894.1
[7] VCV000848845.21 - ClinVar - NCBI (nih.gov)
[8] NM_015506.3(MMACHC):c.271dup (p.Arg91fs) AND Cobalamin C disease - ClinVar - NCBI (nih.gov)
[9] Identification of the gene responsible for methylmalonic aciduria and homocystinuria, cblC type. By Lerner-Ellis, et. al. February 2006. Nature Genetics 38(1):93-100 DOI:10.1038/ng1683
[10] Distinct clinical, neuroimaging and genetic profiles of late-onset cobalamin C defects (cb1C): a report of 16 Chinese cases. By Wang et. al. Orphanet J Rare Dis. 2019; 14: 109. Published online 2019 May 15. doi: 10.1186/s13023-019-1058-9 PMCID: PMC6521494 PMID: 31092259.
[11] Nitrous Oxide-Induced Vitamin B12 Deficiency Resulting in Myelopathy, By Campdesuner, et. al. Cureus. 2020 Jul 9;12(7):e9088. doi: 10.7759/cureus.9088. PMCID: PMC7366039 PMID: 32685323
[12] INHIBITION OF NITRIC OXIDE SYNTHASE BY COBALAMINS AND COBINAMIDES, By Weinberg, et. al. Free Radic Biol Med. PMC: 2010 Jun 15. Published in final edited form as: Free Radic Biol Med. 2009 Mar 27;46(12):1626–1632. doi: 10.1016/j.freeradbiomed.2009.03.017. PMCID: PMC2745708 NIHMSID: NIHMS105833 PMID: 19328848