Mechanism of Action
Vitamin B12 acts as a cofactor for two essential enzymes. The first, methionine synthase, catalyzes the reconversion of homocysteine to methionine in the cytoplasm. This reaction simultaneously regenerates S-adenosylmethionine (SAM), the body's primary methyl group donor. SAM is involved in DNA methylation, neurotransmitter synthesis and creatine production.
The second enzyme, methylmalonyl-CoA mutase, operates within the mitochondria, the cell's energy powerhouses. It converts methylmalonyl-CoA to succinyl-CoA, a fuel for the Krebs cycle. This cycle is the central pathway for energy production. B12 insufficiency causes methylmalonic acid to accumulate, an early functional marker of inadequate status.
In the nervous system, B12 participates in myelin synthesis (the protective sheath around nerve fibers). Maintaining this sheath determines nerve conduction speed and the preservation of cognitive functions with age.
Key Benefits
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More day-to-day energy: vitamin B12 contributes to normal energy-yielding metabolism, serving as a cofactor for mitochondrial energy production via the Krebs cycle.
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A better-regulated homocysteine level: vitamin B12 contributes to normal homocysteine metabolism, an amino acid produced by the methylation cycle.
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A better-maintained nervous system: vitamin B12 contributes to normal functioning of the nervous system. It takes part in the synthesis of myelin, the sheath that insulates nerve fibers, and in maintaining nerve conduction.
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Well-renewed blood: vitamin B12 contributes to normal red blood cell formation, the cells that carry oxygen. This role is documented by data on erythrocyte maturation.
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A supported immune system: vitamin B12 contributes to the normal function of the immune system. Immune cells are among the fastest-renewing cell lines in the body.
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Cell renewal: vitamin B12 has a role in the process of cell division. It takes part in DNA synthesis, the step that precedes any division.
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Better mental balance: vitamin B12 contributes to normal psychological function. This effect draws on its role in the synthesis of neurotransmitters, the brain's chemical messengers, and in cerebral methylation.
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Less fatigue: vitamin B12 contributes to the reduction of tiredness and fatigue. This benefit stems from its involvement in cellular energy production and red blood cell formation.
Dosage & Forms
Three forms of vitamin B12 dominate the supplementation market. Cyanocobalamin is a synthetic form, stabilised by a cyanide group. Adenosylcobalamin and methylcobalamin are the two coenzyme forms found in human physiology, the first in mitochondria, the second in the cytoplasm. The available work indicates that all three follow the same route inside the cell. Each is reduced to a common cobalamin core, then rebuilt into its active form.
Singular selects methylcobalamin. This choice sets aside cyanocobalamin, the only form for which a high dose has been associated with a faster decline in renal function in people whose function is already impaired. The formula offers three calibration tiers: 250 µg (low tier), 500 µg (intermediate tier) and 1,000 µg (high tier), adjusted according to the biological profile.
The European nutritional reference intake is set at 2.5 µg per day. Supplementation doses are deliberately higher. Intestinal absorption of B12 relies on gastric intrinsic factor, whose receptors saturate between 1.5 and 2.5 µg per intake. Beyond that threshold, a passive absorption of about 1% of the dose remains, and it depends on no transporter.
In the Singular Formula
Inclusion rationale
Vitamin B12 contributes to normal energy-yielding metabolism, to normal functioning of the nervous system, to normal homocysteine metabolism, to normal psychological function, to normal red blood cell formation, to the normal function of the immune system and to the reduction of tiredness and fatigue. It also has a role in the process of cell division. A unique vitamin among all: it contains cobalt in its corrin ring, is exclusively synthesized by microorganisms, and its absorption requires a complex mechanism involving gastric intrinsic factor. The prevalence of B12 insufficiency increases significantly with age, affecting up to 20% of people over 60, due to the progressive decrease in gastric acid and intrinsic factor production. Vegan diets imperatively require supplementation. In the formula, B12 takes part in the methylation cycle alongside vitamin B9 (5-MTHF) and vitamin B6 (P-5-P), together ensuring efficient remethylation of homocysteine to methionine. The methylcobalamin form selected is one of the two active coenzyme forms of B12, the one that operates in the cell cytoplasm. This choice sets aside cyanocobalamin. At high doses, that form has been associated with a faster decline in renal function in people whose function is already impaired.
Selected form
Vitamin B12 as methylcobalamin, one of the two coenzyme forms found in human physiology. Cyanocobalamin, the most widespread synthetic form on the market, occurs in human tissues only in trace amounts. Methylcobalamin takes part in the methionine cycle and homocysteine metabolism. Vitamin B12 contributes to normal energy-yielding metabolism, normal red blood cell formation and normal functioning of the nervous system.
Formula dosage
0 to 1,000 µg.
Dose expressed as active substance, excluding excipients and carriers of the raw material.
Synergies in the formula
Safety & Precautions
Vitamin B12 has a favorable safety profile. No tolerable upper intake level has been defined by European authorities: the reference opinion concludes that no clearly defined adverse effect allows one to be set. Absorption is self-limited by gastric intrinsic factor capacity.
Supplementation is not recommended in cases of known hypersensitivity to cobalt or cobalamins, nor for people monitored for a myeloproliferative disorder. Acne-like eruptions have been described after vitamin B12 intake, by mouth as well as by injection. They remain rare and resolve within three to six weeks of stopping. Certain drug interactions deserve attention: metformin, proton pump inhibitors and H2 receptor antagonists can reduce B12 absorption. Individuals taking these medications benefit from regular monitoring of their status.
Pregnant and breastfeeding women can consume vitamin B12 within recommended intakes. Medical advice is recommended before any high-dose supplementation.
Scientific Studies
| Authors | Year | Type | Journal | |
|---|---|---|---|---|
| Didangelos T et al. | 2021 | Randomised Controlled Trial | Nutrients | View on PubMed |
Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial Randomised, double-blind, placebo-controlled trial. 90 adults on long-term metformin received 1,000 µg of oral methylcobalamin daily for one year. Plasma vitamin B12 in the active group rose from 232 to 777 pmol/L. | ||||
| Hill MH et al. | 2013 | Randomised Controlled Trial | Journal of Nutrition | View on PubMed |
A vitamin B-12 supplement of 500 μg/d for eight weeks does not normalize urinary methylmalonic acid or other biomarkers of vitamin B-12 status in elderly people with moderately poor vitamin B-12 status Randomised placebo-controlled trial in 100 older people with moderately poor B12 status, comparing 10, 100 and 500 µg per day for eight weeks. All biomarkers showed a dose response. After 500 µg for eight weeks, 8% still had non-normalised plasma vitamin B12 and 12% non-normalised holotranscobalamin. | ||||
| Obeid R, Fedosov SN, Nexo E | 2015 | Review | Molecular Nutrition & Food Research | View on PubMed |
Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency Review of the assimilation pathways of the four vitamin B12 forms. The authors conclude that methylcobalamin and adenosylcobalamin follow the same intracellular route as cyanocobalamin, and that supplementing a coenzyme form is unlikely to be advantageous. | ||||
| Spence JD, Yi Q, Hankey GJ | 2017 | Meta-analysis | The Lancet Neurology | View on PubMed |
B vitamins in stroke prevention: time to reconsider Individual-patient meta-analysis of two large trials (VISP and VITATOPS). Participants with impaired renal function exposed to high-dose cyanocobalamin drew no benefit from B vitamin therapy, whereas those with normal renal function benefited significantly. | ||||
| Allen LH | 2009 | Review | American Journal of Clinical Nutrition | View on PubMed |
How common is vitamin B-12 deficiency? Review of the prevalence of low vitamin B12 status. In large surveys in the United States and the United Kingdom, about 6% of people aged 60 and over have plasma vitamin B12 below 148 pmol/L, and closer to 20% have marginal status (148 to 221 pmol/L). | ||||
| Green R et al. | 2017 | Review | Nature Reviews Disease Primers | View on PubMed |
Vitamin B12 deficiency Landmark review covering the epidemiology, pathophysiological mechanisms, diagnosis and management of vitamin B12 insufficiency. | ||||
| Porter K et al. | 2016 | Review | Nutrients | View on PubMed |
Causes, Consequences and Public Health Implications of Low B-Vitamin Status in Ageing Review of the causes and consequences of low B-vitamin status in ageing populations, including absorption factors and insufficiency prevalence. | ||||