Supplement evidence

062 / 575Vitamin form

Methylcobalamin

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The short answer

A vitamin B12 form that treats deficiency; superiority over cyanocobalamin for most outcomes is unproven.

Evidence and scope: Established for an indicated use
This status does not grade the ingredient for every goal, outcome, or person.
Important limitation: The benefit is tied to the stated indication, dose, and population; it is not evidence of broader disease prevention or longer life.
Before deciding: Key concern: Investigate deficiency cause and do not rely on supplements for neurologic symptoms without evaluation.

01 / PRACTICAL GUIDE

Dose, absorption, and combinations

These are indication-specific reference or studied ranges—not a personalized prescription. Start with the objective, then check the form, label, medicines, and health conditions.

Reference range by objective

Confirmed deficiencyOften 1,000–2,000 mcg/day orally when high-dose oral treatment is appropriate

Reference or studied range—not a personalized prescription. The product label or a clinician may specify a different dose.

Dose source ↗

More is not automatically better. A clinician or product label may specify a different amount.

Absorption / solubilityWater-soluble

Water-soluble or readily water-dispersible. This does not mean excess is always harmless.

How it is commonly taken

May be taken with or without food.

Do not combine casually

Investigate deficiency cause and do not rely on supplements for neurologic symptoms without evaluation.

Dose and use source ↗

Dose and use links lead to primary or official source material. Search links are discovery tools, not proof that every returned paper applies.

02 / EVIDENCE

What the research says

We keep supportive, mixed, negative, safety, and contextual findings together. The headline never replaces the underlying papers.

3research papers in this ledger

17unique primary studies represented

1,832unique participants represented

These are audited counts for this JIVANA collection, not search-result totals. Participants are counted once when multiple papers use the same cohort; review papers are not added again to participant totals.

Open the research timelineResearch timeline

Entries are ordered by publication year. A study period appears only when the source reports it.

2026

Mixed or qualifiedPMID 41548600 · IRCT20210925052566N3

Efficacy of Oral Vitamin B-12 at 1000 μg Compared with 2000 μg on Neuropathic Outcomes in Patients with Diabetic Peripheral Neuropathy and Low Serum Vitamin B-12

Symptoms improved similarly at both doses, disability scores did not change, and 2,000 μg raised B12 more without extra neuropathic benefit. Without placebo, efficacy versus no treatment cannot be established; an eGFR decline signal in the higher-dose group warrants caution rather than a causal safety claim.

Published: 2026Duration: 16 weeksn=35 participants

Study design and methods

Design: Randomized, open dose-comparison trial without placebo
Population: 35 adults with type 2 diabetes, diabetic peripheral neuropathy, and vitamin B12 below 200 pg/mL; 32 completed
Intervention: Oral methylcobalamin 1,000 or 2,000 μg/day
Outcome: Neuropathy symptoms and disability, serum B12, kidney measures, and adverse events

Funding or conflict note: The authors declared no conflicts of interest.

Open research record ↗

2021

Supports a specific usePMID 33513879

Vitamin B12 Supplementation in Diabetic Neuropathy: A 1-Year, Randomized, Double-Blind, Placebo-Controlled Trial

B12 rose and several nerve-conduction, pain, quality-of-life, and sudomotor measures improved. Cardiovascular autonomic reflex tests and a clinical examination score did not improve, so benefits were selective and apply to a low-B12, long-term-metformin population.

Published: 2021Duration: 1 yearn=90 participants

Study design and methods

Design: Randomized, double-blind, placebo-controlled trial
Population: 90 adults with type 2 diabetes taking metformin for at least 4 years, peripheral and autonomic neuropathy, and vitamin B12 below 400 pmol/L
Intervention: Oral methylcobalamin 1,000 μg/day or placebo
Outcome: Vitamin B12, nerve conduction, pain, quality of life, sudomotor function, autonomic tests, and clinical examination scores

Funding or conflict note: The supplement was provided by a company, which the authors reported had no role in the study; the authors declared no conflict of interest.

Open research record ↗

2020

Mixed or qualifiedPMID 32716261

Effectiveness of mecobalamin in the treatment of peripheral neuropathy: a systematic review and meta-analysis of randomized controlled trials

Mecobalamin alone or in combinations improved a broadly defined clinical-response outcome, and only combinations improved nerve conduction. Neither approach improved pain or symptom scores; 11 of 15 trials had high risk of bias, making certainty low despite no serious trial adverse events.

Published: 2020Duration: Varied across 15 randomized trialsn=1,707 participants15 primary studies represented

Study design and methods

Design: Systematic review and meta-analysis of 15 randomized controlled trials
Population: 1,707 patients with diabetic or herpetic peripheral neuropathy
Intervention: Mecobalamin alone or combined with other treatments versus controls
Outcome: Clinical response, nerve conduction, pain, symptom scores, and adverse events

Open research record ↗

Unscreened discovery appendix—not evidence11 candidate publicationsSearch run: Aug 21, 2026

Complete for the displayed PubMed query at the search timestamp—not for all databases or every possible synonym. Candidates can be irrelevant, duplicate the same study, or report negative findings. They are never summed as evidence or participants until screened.

03 / SOURCES

Start with the source material

Official evidence overviewPubMed bounded human-evidence search Live PubMed discovery searchNational Library of Medicine

The live search is for discovery only. Search-result counts change and are not included in the audited totals above.

Recent PubMed discovery recordsDirect links to the first 12 records returned by the reproducible search. These are discovery candidates—not reviewed summaries or a count of supportive findings.

04 / EXPERT CONTEXT

Expert context—not evidence

Expert positions are dated context—not scientific evidence. They never raise the evidence status or become consensus by repetition.

No direct, source-verified endorsement is currently recorded. Research authorship or discussion alone is not treated as endorsement.