Improvement after a supplement is not the same as a comparative result
Start with the comparison. A before-and-after change alone cannot isolate the contribution of an ingredient.
Vitamin B12
Nutrient status
Partial research summary
Studies with an unspecified organism reported both no clear between-group difference and a change with no confirmed comparison group for Vitamin B12 levels.
Single-ingredient studies · Scope not specified · Includes patient groups · between-group comparison · comparator not confirmed
Publications for this result: 3 (1 awaiting review included)
Other outcomes and study details
Distinct publications linked to this topic: 22
- Study conditions differ; results are shown descriptively and are not pooled.
- Some publications have not cleared source or interpretation review.
- Some papers could not be reviewed, so this summary covers only findings that could be confirmed.
What has been studied?
Distinct human comparison papers: 4
Some studies tested several ingredients together. Those results cannot show this ingredient’s separate effect or establish synergy.
homocysteine
- Comparison result:A better result than the comparison group was reported.Patient group · Combination study · 12 weeks
Measurement and study conditions
- Controlled human study
- Randomized trial
- Ingredient combination
- Patient group
- Biomarker
- Between-group comparison
- Timepoint: 12 weeks
- Study comparison: Vitamin B complex versus placebo; combination effect cannot be attributed to vitamin B12 alone.
indirect DNA damage
Research with unclear study subject or type
- A change was reported, but the comparison could not be confirmed.Deficiency group · Single ingredient
Measurement and study conditions
- Review
- Review
- Single ingredient
- Deficiency group
- Mechanistic outcome
- Study subject not identified
- Timepoint: Unspecified
- Study comparison: Review-level mechanistic claims; no clinical comparative outcome
levels of B12
Research with unclear study subject or type
- A change was reported, but the comparison could not be confirmed.Patient group
Measurement and study conditions
- Review
- Systematic review
- Unknown intervention
- Patient group
- Biomarker
- Study subject not identified
- Timepoint: unspecified
- Study comparison: observational serum/plasma B12 association across BMI categories; not supplementation
serum vitamin B12 level
Research with unclear study subject or type
- A change was reported, but the comparison could not be confirmed.Patient group · Single ingredient · Varied across included studies
Measurement and study conditions
- Review
- Systematic review
- Single ingredient
- Patient group
- Biomarker
- Study subject not identified
- Timepoint: Varied across included studies
- Study comparison: Within-study serum vitamin B12 changes after supplementation; review does not report a common compar
Other measured outcomes (5)
tHcy
- Comparison result:A better result than the comparison group was reported.Deficiency group · Single ingredient · 12 months
Measurement and study conditions
- Controlled human study
- Randomized trial
- Single ingredient
- Deficiency group
- Secondary outcome
- Between-group comparison
- Timepoint: 12 months
- Study comparison: B12 versus placebo on a shared multinutrient background
tHcy concentration
- Comparison result:A better result than the comparison group was reported.Separable contribution
Measurement and study conditions
- Controlled human study
- Randomized trial
- Separable contribution
- Unspecified population
- Outcome role not specified
- Between-group comparison
- Timepoint: unspecified
- Study comparison: unspecified
vitamin B12
Research with unclear study subject or type
- A change was reported, but the comparison could not be confirmed.General population
Measurement and study conditions
- Meta-analysis
- Meta-analysis
- Unknown intervention
- General population
- Biomarker
- Study subject not identified
- Timepoint: cross-sectional; not robust in prospective analyses
- Study comparison: Higher vs lower vitamin B12 concentrations in observational studies
Vitamin B12 deficiency
- Comparison result:Results were mixed for this outcome.Patient group
Measurement and study conditions
- Review
- Systematic review
- Unknown intervention
- Patient group
- Biomarker
- Between-group comparison
- Timepoint: unspecified
- Study comparison: PPI users versus non-users; pooled vitamin B12 deficiency odds ratio slightly elevated, but heteroge
Vitamin B12 levels
Research with unclear study subject or type
- No clear difference in this measurement was found between the compared groups.General population · Single ingredient
Measurement and study conditions
- Meta-analysis
- Meta-analysis
- Single ingredient
- General population
- Primary outcome
- Between-group comparison
- Study subject not identified
- Timepoint: unspecified
- Study comparison: No statistically significant differences among B12 administration routes for vitamin B12 levels
- A change was reported, but the comparison could not be confirmed.Patient group
Measurement and study conditions
- Meta-analysis
- Meta-analysis
- Unknown intervention
- Patient group
- Biomarker
- Study subject not identified
- Timepoint: unspecified
- Study comparison: vitiligo patients vs controls
This result is held for interpretation. That does not mean research found no effect.
Outcome groups needing additional review (4)
- complete resolution · Distinct papers needing additional review: 1Evidence criteria check: 1
- hemoglobin levels · Distinct papers needing additional review: 1Applicability check needed: 1
- homocysteine concentrations · Distinct papers needing additional review: 1Evidence criteria check: 1
- serum B12 · Distinct papers needing additional review: 1Evidence criteria check: 1
One paper can appear under multiple measured outcomes or review reasons, so these counts should not be added together.
Research topics to explore
Research topics to explore
Review findings reported in each research area.
Topics with more linked papers appear first.
- View selected result
Nutrient status
Related papers 22 · human comparison papers 4
- View results
Cognition
Related papers 3 · comparison findings need further review
- cognitive function outcomes · Some studies used more than one ingredient · Comparison details unconfirmed
- View results
Stress and mood
Related papers 3 · comparison findings need further review
- depression · Comparison details unconfirmed
- measures of depression · Some studies used more than one ingredient · Comparison details unconfirmed
- View results
Bone, joint, and mobility
Related papers 2 · comparison findings need further review
- nonspine fracture risk · Some studies used more than one ingredient · Some studies included patients or people with a deficiency · Comparison details unconfirmed
- View results
Exercise performance
Related papers 2 · human comparison papers 1
- Physical performance level · No clear difference between groups · Some studies used more than one ingredient · Some studies included patients or people with a deficiency
- neurological functional recovery · Interpretation held
- View results
Glucose and metabolic health
Related papers 2 · human comparison papers 1
- HbA1c · Improvement reported · Some studies included patients or people with a deficiency
- MetS · Comparison details unconfirmed
- View results
Digestion and gut health
Related papers 1 · comparison findings need further review
- gut barrier tight junctions · Animal or cell research · Comparison details unconfirmed
- View results
Fatigue and energy
Related papers 1 · comparison findings need further review
- View results
Men's health
Related papers 1 · comparison findings need further review
- sperm count · Interpretation held
- sperm DNA damage · Interpretation held
More outcome groups: 1
- View results
Migraine and pain
Related papers 1 · comparison findings need further review
- pain score · Some studies included patients or people with a deficiency · Comparison details unconfirmed
Data coverage and detailed study classifications
Paper counts are separated by research topic below. One paper may contribute to multiple findings.
Analysis status: Public-ready
Ingredient analysis date:
How the grade was determined: B
The 57.4 evidence score includes 1 independent human studies and 1 clinical studies in the representative benefit area. The B tier remains conservative because of the evidence centers on contextual or measured outcomes rather than general-use effects, limited repetition across independent human clinical studies.
The grade is based mainly on the research area with the most evidence. It does not mean the same result was found in other areas.
Papers linked to this ingredient overall: 96
Papers linked to this topic 22 · distinct papers 22 · papers with a confirmed human comparison 4 · papers needing additional review 12
Ingredient-wide papers, topic-linked papers, and sources in outcome groups use different scopes. Adding source counts may count the same paper more than once.
- complete resolution: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- hemoglobin levels: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- homocysteine: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 1
- homocysteine concentrations: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- indirect DNA damage: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- levels of B12: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- serum B12: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- serum vitamin B12 level: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- tHcy: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 1
- tHcy concentration: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 1
- vitamin B12: Sources represented in this measurement group: 1 · Distinct papers with human comparisons for this outcome: 0
- Vitamin B12 deficiency: Sources represented in this measurement group: 2 · Distinct papers with human comparisons for this outcome: 1
- Vitamin B12 levels: Sources represented in this measurement group: 3 · Distinct papers with human comparisons for this outcome: 0
Nutrient status
What the research found
homocysteine
The study reported improvement in this measurement.
Controlled study in people · Ingredient combination · Patient group
Several ingredients were used together. This does not establish the effect of this ingredient alone or synergy.
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
tHcy
The study reported improvement in this measurement.
Controlled study in people · Single ingredient · Deficiency group
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
tHcy concentration
The study reported improvement in this measurement.
Controlled study in people · Separable contribution · Unspecified population
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
vitamin B12 deficiency
Results for this measurement were mixed; no consistent conclusion can be drawn.
Review · Unknown intervention · Patient group
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
vitamin B12 levels
No clear difference in this measurement was found between the compared groups.
Meta-analysis · Single ingredient · General population
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
indirect DNA damage
A change was reported, but the comparison could not be confirmed.
Review · Single ingredient · Deficiency group
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
levels of B12
A change was reported, but the comparison could not be confirmed.
Review · Unknown intervention · Patient group
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
serum vitamin B12 level
A change was reported, but the comparison could not be confirmed.
Review · Single ingredient · Patient group
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
vitamin B12
A change was reported, but the comparison could not be confirmed.
Meta-analysis · Unknown intervention · General population
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
vitamin B12 levels
A change was reported, but the comparison could not be confirmed.
Meta-analysis · Unknown intervention · Patient group
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
complete resolution
The study needs further checking before its result can be interpreted.
Review · Unknown intervention · Deficiency group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
hemoglobin levels
The study needs further checking before its result can be interpreted.
Other evidence · Ingredient combination · Patient group
Several ingredients were used together. This does not establish the effect of this ingredient alone or synergy.
Within-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
homocysteine concentrations
The study needs further checking before its result can be interpreted.
Review · Unknown intervention · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
serum B12
The study needs further checking before its result can be interpreted.
Controlled study in people · Ingredient combination · General population
Several ingredients were used together. This does not establish the effect of this ingredient alone or synergy.
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Controlled study in people · Single ingredient · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
2 papers · 2 measured outcomes
2 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Meta-analysis · Unknown intervention · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Observational study · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Other evidence · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Other evidence · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Vitamin B12 deficiency
The study needs further checking before its result can be interpreted.
Other evidence · Unknown intervention · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Vitamin B12 levels
The study needs further checking before its result can be interpreted.
Meta-analysis · Unknown intervention · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Cognition
What the research found
cognitive function outcomes
A change was reported, but the comparison could not be confirmed.
Meta-analysis · Ingredient combination · General population
Several ingredients were used together. This does not establish the effect of this ingredient alone or synergy.
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Observational study · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Review · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Stress and mood
What the research found
depression
A change was reported, but the comparison could not be confirmed.
Meta-analysis · Unknown intervention · Unspecified population
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
measures of depression
A change was reported, but the comparison could not be confirmed.
Meta-analysis · Ingredient combination · General population
Several ingredients were used together. This does not establish the effect of this ingredient alone or synergy.
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Review · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Bone, joint, and mobility
What the research found
nonspine fracture risk
A change was reported, but the comparison could not be confirmed.
Controlled study in people · Ingredient combination · Patient group
Several ingredients were used together. This does not establish the effect of this ingredient alone or synergy.
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Controlled study in people · Single ingredient · Unspecified population
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Exercise performance
What the research found
Physical performance level
No clear difference in this measurement was found between the compared groups.
Controlled study in people · Ingredient combination · Patient group
Several ingredients were used together. This does not establish the effect of this ingredient alone or synergy.
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
neurological functional recovery
The study needs further checking before its result can be interpreted.
Other evidence · Single ingredient · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Glucose and metabolic health
What the research found
HbA1c
The study reported improvement in this measurement.
Controlled study in people · Single ingredient · Patient group
Between-group comparison
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
MetS
A change was reported, but the comparison could not be confirmed.
Meta-analysis · Unknown intervention · Unspecified population
Analysis coverage and paper counts
1 paper · 1 measured outcome
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Digestion and gut health
What the research found
gut barrier tight junctions
A change was reported in animal or cell research.
Animal study · indirect · Single ingredient · General population
This finding comes from animal or cell research. It does not establish the same effect in people.
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Fatigue and energy
What the research found
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Meta-analysis · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Men's health
What the research found
sperm count
The study needs further checking before its result can be interpreted.
Review · Single ingredient · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
sperm DNA damage
The study needs further checking before its result can be interpreted.
Review · Single ingredient · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
sperm motility
The study needs further checking before its result can be interpreted.
Review · Single ingredient · Patient group
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Unspecified measured outcome
The study needs further checking before its result can be interpreted.
Review · Unknown intervention · Unspecified population
The comparison could not be confirmed.
Analysis coverage and paper counts
1 paper · 1 measured outcome
1 papers held from direction counts
Review overlap with primary papers is unknown; counts stay separate.
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
Migraine and pain
What the research found
pain score
A change was reported, but the comparison could not be confirmed.
Controlled study in people · Single ingredient · Patient group
Analysis coverage and paper counts
1 paper · 1 measured outcome
Direction counts are distinct papers within each row. Outcome contributions count endpoint results, so one paper may contribute more than once.
How to read research findings
How should I read research findings?
Research guidesNo clear difference and an uninterpretable result are different
A reported null comparison contains a result. An abstract without an interpretable comparison leaves a question unresolved.
Paper counts and study counts are different
Count original research separately from research that reanalyzes it. Publication volume is neither replication nor a quality rating.
Side effects and combination findings
Findings from this ingredient alone are shown separately from those involving another supplement or medication.
Caution findings
3
Findings from individual and combined use, plus reviewed cautions
Key precautions
No reviewed caution rules are available yet. Reported caution findings are shown below.
These findings were reported in studies. They do not predict an individual's experience.
Findings to review with care
Side effects reported for the ingredient alone are separated from findings involving another supplement or medication.
Cautions reported with another supplement or medication
These studies reported worsening outcomes, reduced absorption, or other cautions with combined use. They do not predict an individual's outcome.
AntacidsAntacids may alter vitamin B12 absorption and utilization, increasing deficiency risk.
MetforminMetformin-treated T2DM patients are at higher risk of vitamin B12 deficiency and more severe neuropathy symptoms; supplementation may prevent or treat these conditions.
Proton pump inhibitorsPPI use may impact the absorption of vitamin B12, resulting in a slightly increased risk of deficiency.