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MyDeficiencies

Ergocalciferol

Vitamin D2 secosteroid, prohormone (prescription strength)

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Findings for this medication

Research about this medication, graded for how strongly each finding can be attributed to it. Nothing here describes your own levels.

Ergocalciferol requires the same obligate two-step activation as cholecalciferol, hepatic 25-hydroxylation followed by renal 1-alpha-hydroxylation, but the two forms are not pharmacokinetically identical. This review confirmed that ergocalciferol's hepatic 25-hydroxylation is carried out by CYP2R1 but, unlike cholecalciferol, is not performed by CYP27A1; the resulting metabolites bind vitamin D binding protein with lower affinity than the corresponding D3 metabolites; and once activated, ercalcitriol (1,25-dihydroxyergocalciferol) binds the vitamin D receptor with affinity similar to calcitriol. These are not cosmetic differences: a randomized, investigator-blinded head-to-head trial in chronic kidney disease patients dosing both forms at an identical prescription-strength 50,000 IU once weekly found cholecalciferol raised total 25-hydroxyvitamin D significantly more at 12 weeks (45.0 vs 30.7 ng/mL, P<0.01), and, notably, found that ergocalciferol dosing significantly suppressed the body's own endogenous 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 subfractions, a genuine, drug-specific pharmacodynamic finding rather than a marketing distinction. Ergocalciferol's FDA-approved indications, hypoparathyroidism, vitamin D resistant rickets, and familial hypophosphatemia, are narrower and older than the general deficiency-correction indication now more commonly filled with cholecalciferol, reflecting ergocalciferol's history as the original prescription vitamin D product.

Vitamin D2 secosteroid, prohormone (prescription strength) · ATC A11CC01 · also sold as generic Ergocalciferol 50 and 000 IU capsules (Banner Life Sciences and Alembic and Chartwell RX and Bionpharma and SigmaPharm and Epic Pharma and Torrent and Virtus and others) · reviewed 2026-09-28. This describes research about the medication. It does not say anything about your own levels or health.

How to read the evidence grades

These colours describe how strongly a finding can be attributed to the medication in the research. They are not a severity score and they say nothing about your own health.

Grades describe how strongly a finding can be attributed to Ergocalciferol in the research — not how common it is, how serious it would be, and not anything about you personally.

Red — Severe
Two or more independent Tier A sources, this drug in the cohort, the nutrient directly measured, consistent direction, clinically meaningful magnitude, a named mechanism, no substantial contradicting Tier A evidence.
Orange — Moderate
At least one Tier A source with this drug in the cohort showing a real but bounded deficit: an exposure window, a subgroup, low frequency, or a functional rather than circulating deficit.
Yellow — Low
Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction.
Not graded — disclosed evidence gap
Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result.Source definition: Not gradeable under the rules above because nothing has been measured. Published as a documented gap, never as reassurance that there is no effect.

What the research found

No entry met the red threshold

Red — Severe

See study details

This tier is printed empty deliberately, per this protocol's rule that an empty tier is itself a finding.

Full detail and limits

What the grade means here: Two or more independent Tier A sources, this drug in the cohort, the nutrient directly measured, consistent direction, clinically meaningful magnitude, a named mechanism, no substantial contradicting Tier A evidence.

Limits on what this shows

  • What would fill this tier: A second, independent Tier A source documenting ergocalciferol-specific hypercalcemia at standard prescribed dosing (not just at megadose, chronic unmonitored, or erroneous-administration exposure) without a contradicting null trial, or a newly published Tier A trial isolating ergocalciferol monotherapy for any of the seven mandatory categories with a severe, consistent, mechanistically named effect.

Why empty

Ergocalciferol's most severe drug-specific finding, hypercalcemia and toxicity, is real and regulatory-labeled but is directly contradicted at standard 50,000 IU once-weekly prescription dosing by a Tier A randomized trial that produced no hypercalcemia in 12 weeks; per this protocol's red criterion of "no substantial contradicting Tier A evidence," that null trial bars a red grade and the entry is instead graded orange with the boundary stated in its title. No other classical nutrient or physiological category in this dossier reached even a single confirmed drug-specific Tier A source, let alone the two independent Tier A sources red requires.

Calcium, hypercalcemia

Orange — Moderate

See study details

Ergocalciferol directly raises serum calcium once activated, the same mechanism shared by every vitamin D form, and genuine drug-specific regulatory and case-report evidence documents this risk, but a Tier A randomized trial at the standard 50,000 IU once-weekly, 12-week prescription regimen found no hypercalcemia in the ergocalciferol arm, bounding the real risk to prolonged, supraphysiologic, or erroneous-dose exposure rather than a standard monitored course.

Full detail and limits

What the grade means here: At least one Tier A source with this drug in the cohort showing a real but bounded deficit: an exposure window, a subgroup, low frequency, or a functional rather than circulating deficit. ORANGE, excess direction, bounded

Limits on what this shows

  • Key negative/null findings: The Wetmore et al. 2016 trial is a genuine, drug-specific null finding for hypercalcemia at the standard 50,000 IU weekly, 12-week regimen commonly used in real-world prescription-strength ergocalciferol therapy; this null result directly bounds how far this entry can be graded and is the reason it is orange rather than red.
  • At-risk subgroups: Prolonged high-dose regimens continued past correction of deficiency, concomitant thiazide diuretics, erroneous or unmonitored high-dose administration (the disclosed 2012 infant case), granulomatous disease, primary hyperparathyroidism, renal impairment (a population in which ergocalciferol is specifically indicated for hypoparathyroidism and familial hypophosphatemia, raising the stakes of monitoring), and infants specifically, for whom the label separately warns that hypersensitivity to vitamin D may produce idiopathic hypercalcemia requiring strict dietary restriction.
  • Counter-evidence on record: The Wetmore RCT's null hypercalcemia result at standard dosing is direct, drug-specific Tier A counter-evidence against an unqualified severe-risk framing, which is why this entry is graded orange rather than red.

Regulatory status

The ergocalciferol label (1.25 mg, 50,000 USP units capsule) lists hypercalcemia, malabsorption syndrome, hypervitaminosis D, and abnormal sensitivity to vitamin D toxicity as contraindications, states explicitly that "the range between therapeutic and toxic doses is narrow," and requires blood calcium and phosphorus determinations at least every two weeks plus monthly bone x-ray examination until stabilized; thiazide diuretic co-therapy is separately flagged as raising hypercalcemia risk in hypoparathyroid patients.

Population evidence

Randomized, investigator-blinded, two-arm trial (British Journal of Nutrition, 2016), 44 non-dialysis chronic kidney disease patients stages 3 to 5 with baseline 25(OH)D under 30 ng/ml, ergocalciferol 50,000 IU orally once weekly for 12 weeks. No hypercalcemia developed in the ergocalciferol arm (or the cholecalciferol comparator arm); two cholecalciferol-treated participants, not ergocalciferol-treated, exceeded the trial's 80 ng/ml 25(OH)D safety threshold and were withdrawn early though retained in analysis. Ergocalciferol directly administered. Tier A, and a genuine, drug-specific null finding at standard prescription dosing. Separately, a Crossref bibliographic search located four ergocalciferol-specific published case reports of vitamin D toxicity or hypercalcemia (Reactions Weekly digests, 2011, 2019, and 2022; and a 2012 report specifically describing hypercalcemia and nephrocalcinosis in an infant following erroneous ergocalciferol administration) and a case report and literature review specifically describing an absence of toxicity with chronic daily ergocalciferol megadosing (Stephenson and Peiris, Southern Medical Journal, 2009); full text of all five could not be opened during this review (see Sources), so their quantitative detail is not independently verified here, but their indexed titles confirm ergocalciferol was the specific agent in each, satisfying the cohort test at the bibliographic level. Tier B, disclosed as title-confirmed but not content-verified.

Mechanism

Named: once hydroxylated to the active hormone (ercalcitriol), vitamin D receptor signaling upregulates intestinal transcellular calcium absorption and osteoclastic bone resorption, identical in principle to cholecalciferol's mechanism once activated.

Counter-evidence held on record

This is an excess/retention risk from the drug's own intended pharmacology once activated, not a nutrient deficiency, and it is concentrated in prolonged, supraphysiologic, or erroneous-dose exposure rather than a standard monitored 50,000 IU weekly course. Do not add calcium or additional vitamin D sources on top of prescription-strength ergocalciferol without prescriber-directed monitoring, and never administer outside precise, supervised dosing in infants.

Vitamin K, calcium-deposition interplay, pure class extrapolation

Yellow — Low

See study details

The hypothesis that vitamin D-driven calcium mobilization requires vitamin K-dependent carboxylation of matrix Gla protein and osteocalcin to avoid soft-tissue calcification is mechanistically plausible for ergocalciferol, since both vitamin D forms converge on the same activated hormone and calcium-mobilization pathway, but every combination trial located anywhere in this project used cholecalciferol, not ergocalciferol, leaving this entirely a class-level extrapolation for D2.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, class extrapolation, D2 not in any located trial

Limits on what this shows

  • Key negative/null findings: The AVADEC trial's overall null primary result is the best available evidence and applies only indirectly to ergocalciferol; no vitamin-D-alone or D2-specific arm exists in any source located in this review.
  • At-risk subgroups: Not established for ergocalciferol specifically.
  • Counter-evidence on record: None found specific to ergocalciferol; the class-level null overall trial result is itself the main tempering factor on record.

Regulatory status

Not addressed in the ergocalciferol label reviewed.

Population evidence

No ergocalciferol-specific vitamin K interaction trial was located despite Crossref, DailyMed, Wikipedia, and drugs.com searches during this review. The only randomized combination-trial evidence available in this project is the AVADEC trial substudy (JACC: Advances), a four-center Danish RCT combining cholecalciferol 1,000 IU per day with vitamin K2 720 mcg per day in 304 elderly men with elevated coronary calcification scores, whose overall primary endpoint was not significant (P=0.089) with benefit confined to a prespecified high-baseline-calcification subgroup (P=0.047). Ergocalciferol was not in this trial's cohort. Tier C for the ergocalciferol-specific question.

Mechanism

Named for the hypothesis, not proven for either vitamin D form in isolation: activated vitamin D (ercalcitriol for D2, calcitriol for D3) raises circulating calcium and upregulates Gla-domain proteins that require vitamin K-dependent carboxylation to direct calcium to bone rather than soft tissue.

Counter-evidence held on record

Do not present this as evidence, for ergocalciferol specifically, that co-administered vitamin K2 is required; the only trial evidence located anywhere in this project used cholecalciferol, making this a weaker, purely class-level basis than even the already-capped cholecalciferol entry in the sibling dossier.

Magnesium, cofactor utilization theory, no drug-specific data located

Yellow — Low

See study details

Magnesium is a required cofactor for the cytochrome P450 hydroxylases, CYP2R1, CYP27B1, and CYP24A1, that this review confirmed activate and catabolize ergocalciferol itself, giving genuine mechanistic plausibility that high-dose ergocalciferol therapy could increase magnesium utilization, but no ergocalciferol-specific trial was located, and the best available empirical evidence, generic vitamin D data, not D2-stratified, shows the relationship running predominantly the other way.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, class extrapolation, direction empirically uncertain

Limits on what this shows

  • Key negative/null findings: No direct ergocalciferol-magnesium trial of any kind exists to report a null or positive result from; this is disclosed as a full evidence gap on the direct question, distinct from the plausible class-level cofactor mechanism.
  • At-risk subgroups: Patients with baseline magnesium insufficiency (malabsorption, alcohol use disorder, chronic diuretic use) starting high-dose ergocalciferol repletion, by extension of the same theoretical concern raised for cholecalciferol.
  • Counter-evidence on record: The Vanderbilt trial's direction, magnesium status predicting the vitamin D metabolite response rather than vitamin D dosing changing magnesium, is the strongest empirical evidence located anywhere in this project and runs counter to a "vitamin D depletes magnesium" framing for either form.

Regulatory status

Not addressed in the ergocalciferol label reviewed.

Population evidence

NIH's Magnesium Health Professional Fact Sheet confirms, generically, that magnesium "affects the concentrations of both parathyroid hormone and the active form of vitamin D." No ergocalciferol-specific magnesium supplementation or depletion trial was located in this review. The most relevant empirical data available in this project is a double-blind, 2x2 factorial RCT at Vanderbilt University Medical Center (American Journal of Clinical Nutrition), n=180, testing magnesium supplementation, not any vitamin D form, as the intervention, and measuring endogenous 25(OH)D3 and 24,25(OH)2D3 as outcomes; magnesium's effect on those D3 metabolites was dose-dependent and bidirectional by baseline vitamin D status. This trial did not involve ergocalciferol and measured only D3 metabolites. Tier C for the ergocalciferol-specific question, and only indirectly informative even for cholecalciferol.

Mechanism

Named for magnesium's role as a cofactor for CYP2R1, CYP27B1, and CYP24A1, the same enzyme family confirmed via Wikipedia to process ergocalciferol; not established in the reverse direction for either vitamin D form.

Counter-evidence held on record

This is a theoretical, mechanism-only concern for ergocalciferol, weaker even than the equivalent cholecalciferol entry because no D2-stratified data of any kind was located. Do not present this as an established reason to add magnesium during ergocalciferol therapy.

The five body-system areas

Each finding is counted once, in a single area. Where a study is mentioned in a second area it is context only.

Mitochondrial Burden

Each finding below is counted once, in this area only.

Mitochondrial burden, no ergocalciferol-specific data, class extrapolation only

Yellow — Low

See study details

No ergocalciferol-specific mitochondrial study was located despite multiple search attempts; the only mitochondrial evidence available anywhere in this project is a cholecalciferol-specific human, animal, and cell-culture program showing improved muscle mass, grip strength, and mitochondrial complex activity with D3 repletion, making this a class-level extrapolation for ergocalciferol.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, class extrapolation

Limits on what this shows

  • Key negative/null findings: None specific to ergocalciferol; the class-level source itself measured mitochondrial mechanism data only in animal and cell models, not human tissue, a limitation already present before adding the further D2-versus-D3 extrapolation gap.
  • At-risk subgroups: Not established for ergocalciferol; by extension, older adults with diagnosed deficiency would be the plausible population.
  • Counter-evidence on record: None found contradicting the direction for either vitamin D form.

Regulatory status

Not addressed in the ergocalciferol label reviewed; mitochondrial parameters are not part of ergocalciferol's clinical monitoring.

Population evidence

Communications Biology, 2022: 115 elderly, vitamin D-deficient, pre-sarcopenic adults randomized to cholecalciferol 10,000 IU three times weekly versus placebo for six months, with significant gains in appendicular lean mass (0.57 v. 0.07 kg, P<0.001) and grip strength (0.85 v. 0.09 kg, P<0.001), plus a companion rat depletion model showing state 3 mitochondrial respiration reduced 20 to 30% and complex I, III, and IV activities reduced 45%, 31%, and 52% respectively, with PGC1alpha, NRF1, and NRF2 downregulated. Ergocalciferol was not administered in this trial or its companion animal and cell models. Tier C for ergocalciferol.

Mechanism

Proposed via vitamin D receptor signaling supporting mitochondrial biogenesis (PGC1alpha, NRF1, NRF2 pathways); since ergocalciferol's active metabolite (ercalcitriol) binds the vitamin D receptor with affinity similar to calcitriol, confirmed via Wikipedia during this review, the mechanism is plausible for ergocalciferol in principle, but untested.

Counter-evidence held on record

This is a class-level extrapolation two steps removed from direct evidence: no ergocalciferol-specific data exists, and even the cholecalciferol-specific mechanistic data comes from animal and cell models, not human tissue. Do not present this as evidence that ergocalciferol enhances mitochondrial function.

Oxidative Stress

Each finding below is counted once, in this area only.

Oxidative stress, no ergocalciferol-specific data, class extrapolation only

Yellow — Low

See study details

A Crossref search combining ergocalciferol/vitamin D2 with oxidative stress or antioxidant terms returned no on-topic results; the only relevant evidence in this project is cholecalciferol-specific and itself mixed, a small pooled meta-analytic benefit alongside a null result in the largest single drug-specific trial located for either vitamin D form.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, class extrapolation, mixed direction at class level

Limits on what this shows

  • Key negative/null findings: The cholecalciferol-specific null malondialdehyde result is itself a caution against assuming a reliable antioxidant effect for any vitamin D form, ergocalciferol included; no ergocalciferol-specific data exists to add to or subtract from it.
  • At-risk subgroups: Not established for ergocalciferol.
  • Counter-evidence on record: The class-level null trial is the main counter-evidence available; no ergocalciferol-specific data exists at any tier.

Regulatory status

Not addressed in the ergocalciferol label reviewed.

Population evidence

A systematic review and meta-analysis of vitamin D supplementation trials (pooled, not all confirmed D3-specific) found malondialdehyde standardized mean difference of -0.40 (95% CI -0.60 to -0.21, P<0.001) and total antioxidant capacity standardized mean difference of 0.54 (95% CI 0.29 to 0.79, P=0.001) favoring supplementation, with the authors' own conclusion stating the effect "may not be clinically significant." A cholecalciferol-specific RCT in type 2 diabetes (Frontiers in Endocrinology, 2021, n=130) found no significant effect on malondialdehyde (P=0.884). Neither trial involved ergocalciferol. Tier C for ergocalciferol.

Mechanism

Proposed antioxidant and anti-inflammatory genomic vitamin D receptor signaling at supraphysiologic exposure; plausible for ergocalciferol given its active metabolite's similar vitamin D receptor affinity, but untested for this specific drug.

Counter-evidence held on record

Do not present ergocalciferol as an antioxidant supplement; no drug-specific data exists, and the best class-level evidence available was null in its largest single trial.

Copper and Iron Balance

Copper and iron are assessed separately. Nothing here is counted twice.

Iron, no ergocalciferol-specific trial, class extrapolation plus a labeled outcome caution

Yellow — Low

See study details

No ergocalciferol-specific hepcidin, ferritin, or iron-absorption trial was located; the only mechanistic and trial evidence available in this project is cholecalciferol-specific, showing hepcidin suppression and modestly improved transferrin saturation without a ferritin change, while the ergocalciferol monograph itself separately lists anemia as a labeled adverse reaction of ergocalciferol-induced hypervitaminosis D, a clinical outcome, not a nutrient-status measurement, and therefore not counted as supporting evidence in either direction.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, class extrapolation, mixed direction

Limits on what this shows

  • Key negative/null findings: Ferritin was unchanged in both class-level sources cited; separately, and in the opposite direction, ergocalciferol's own hypervitaminosis-D adverse reaction profile lists anemia as a toxicity-context outcome, underscoring that this is a bounded, dose-dependent physiological system, not a one-directional "vitamin D helps iron" story, at either therapeutic or toxic exposure.
  • At-risk subgroups: Not established for ergocalciferol; patients with anemia of inflammation would be the theoretically relevant population by extension from the cholecalciferol mechanism, while patients experiencing overt hypervitaminosis D from any vitamin D form should have anemia considered among the toxicity picture.
  • Counter-evidence on record: The labeled hypervitaminosis-D anemia entry is disclosed as a labeled outcome, not treated as proof that ergocalciferol depletes iron, since it was not accompanied by a measured iron, ferritin, or hepcidin value in the source reviewed.

Regulatory status

Not addressed in the ergocalciferol FDA label reviewed. A professional pharmacology monograph (drugs.com) lists anemia among the adverse reactions of ergocalciferol-induced hypervitaminosis D, alongside polyuria, polydipsia, hypercalciuria, hypertension, nephrocalcinosis, renal insufficiency, weakness, nausea, and constipation; this is a toxicity-context outcome list, not a measured iron-status finding, and per this protocol's Hard Rule 2 is recorded here as a labeled outcome caution, not graded as nutrient evidence.

Population evidence

Pilot, double-blind, placebo-controlled trial (Clinical Nutrition), n=28, single oral 250,000 IU cholecalciferol dose versus placebo: hepcidin fell 73% in the vitamin D group (P=0.005), ferritin unchanged. A 14-trial, 1,385-participant meta-analysis (Nutrition Journal) found transferrin saturation (mean difference 1.54, P=0.01) and overall iron status (standardized mean difference 0.24, P=0.002) improved with vitamin D supplementation, ferritin unchanged (P=0.91). Neither source involved ergocalciferol. Tier C for ergocalciferol.

Mechanism

Proposed vitamin D receptor-mediated hepcidin suppression, plausible for ergocalciferol via its structurally similar active metabolite, but untested for this specific drug.

Counter-evidence held on record

Do not present ergocalciferol as improving iron utilization; no drug-specific trial data exists, only class-level extrapolation, and the drug's own toxicity profile separately lists anemia as a possible adverse outcome at excessive exposure.

Copper

Not graded — disclosed evidence gap

See study details

Copper

Full detail and limits

What the grade means here: Nothing has been measured here, so this finding cannot be graded. That does not establish either safety or harm, and it is not the same as a White result. UNGRADED

Limits on what this shows

  • Why no grade: Dual condition met: no Tier B or Tier C evidence of an ergocalciferol-specific, or more broadly any vitamin-D-specific, mechanism affecting copper status was found, and no circulating consumer claim that ergocalciferol depletes, retains, or otherwise affects copper status was found either. This is a genuine literature gap, not a finding of safety, and is graded ungraded only after the multi-channel effort described below.

Channels tried

A Crossref bibliographic search combining ergocalciferol/copper/ceruloplasmin returned ten results, none connecting vitamin D to copper status; all ten concerned copper or ceruloplasmin measurement methodology or unrelated clinical conditions. NIH's Copper Health Professional Fact Sheet, read in full, states copper has no known clinically relevant medication interactions and does not mention vitamin D anywhere in its interaction discussion. Beyond this, WebSearch was unavailable for the entirety of this review, this session's shared 200-call budget across the batch's prior thirteen dossiers was already exhausted before research on ergocalciferol began, so all opening WebSearch attempts failed immediately; WebFetch attempts against PubMed, the NCBI eutils API, the Europe PMC REST API, the Semantic Scholar API, and the OpenAlex API were repeatedly rejected at the network gateway level (confirmed via this session's own proxy status log as policy-level connection denials spanning the whole session, not a single blocked attempt) across multiple separate attempts and multiple query phrasings; NCBI Bookshelf's search interface is disallowed by robots.txt, a guessed StatPearls chapter ID resolved to an unrelated article; and both Bing and DuckDuckGo HTML search fallbacks were blocked by robots.txt. This is disclosed as a genuinely tooling-constrained session layered on top of a real, substantively negative content gap in every channel that did respond; a later revision with fuller API access should re-run this category before assuming the gap is purely one of literature non-existence.

Context to disclose

This project's cholecalciferol dossier reached the identical ungraded conclusion for copper via a similarly thorough, similarly tooling-constrained search, consistent with copper simply not being a documented axis of vitamin D pharmacology in either form, though this review cannot rule out that a genuine but hard-to-find literature exists. Some multivitamin and bone-health combination products co-formulate vitamin D with copper alongside calcium, magnesium, and zinc for general nutrition marketing purposes; this reflects product formulation choices, not a documented pharmacological interaction, and is not evidence for a graded entry.

Gut Microbiome Risk

Each finding below is counted once, in this area only.

Gut microbiome risk, no ergocalciferol-specific data, class extrapolation only

Yellow — Low

See study details

No ergocalciferol-specific gut microbiome study was located; the only trial evidence in this project is a cholecalciferol monotherapy RCT that found increased microbiota community stability with mixed-direction taxonomic shifts, making this a class-level extrapolation for ergocalciferol.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, class extrapolation, mixed direction

Limits on what this shows

  • Key negative/null findings: Alpha diversity, the most commonly cited general "health" marker, did not significantly change with cholecalciferol treatment in the source cited; no ergocalciferol data exists to compare.
  • At-risk subgroups: Not established for ergocalciferol.
  • Counter-evidence on record: None specific to ergocalciferol; the class-level source's own mixed-direction taxonomic findings are the main tempering factor.

Regulatory status

Not addressed in the ergocalciferol label reviewed.

Population evidence

Double-blind, placebo-controlled RCT (Microbiology Spectrum), n=41 completers, cholecalciferol 4,000 IU per day for 12 weeks: alpha diversity unchanged in the treatment group while declining in placebo; beta diversity showed significantly increased compositional stability with treatment (P<0.0001); taxonomic shifts were mixed in direction (Bifidobacterium and Anaerostipes enriched; Bacteroides, Faecalibacterium, and Prevotella depleted). Ergocalciferol was not administered in this trial. Tier C for ergocalciferol.

Mechanism

Broader vitamin D receptor biology is proposed as a modulator of gut epithelial tight junctions and antimicrobial peptide expression; not specific to either vitamin D form, and the specific mechanism driving the cited taxonomic shifts was not established even for cholecalciferol.

Counter-evidence held on record

Do not present ergocalciferol as clearly beneficial or clearly harmful to gut microbiome health; no drug-specific data exists at all, and even the class-level cholecalciferol data is mixed in direction.

Oxygen and ATP Output

Oxygen delivery and ATP production are assessed separately. Nothing here is counted twice.

Oxygen delivery / utilization, one disclosed but inaccessible D2-specific trial, otherwise class extrapolation

Yellow — Low

See study details

This review located a genuinely ergocalciferol-specific, human, cohort-appropriate randomized trial directly on point, a single large dose of ergocalciferol improving endothelial function in patients with type 2 diabetes, but its full text could not be opened despite multiple access attempts, so its quantitative results are not independently verified here; the remaining evidence is cholecalciferol-specific class extrapolation showing a null pooled effect on hemoglobin.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, mixed evidence quality

Limits on what this shows

  • Key negative/null findings: The pooled hemoglobin meta-analysis's overall result is a genuine null with high heterogeneity; this review could not independently verify whether the endothelial-function trial found a null or positive result because its full text could not be opened.
  • At-risk subgroups: Not established for ergocalciferol from data this review could independently verify.
  • Counter-evidence on record: The pooled null hemoglobin result is the only verified counter-evidence on record; the Sugden trial's actual direction of effect is unverified and not counted either way.

Regulatory status

Not addressed in the ergocalciferol label reviewed.

Population evidence

Sugden et al., "Vitamin D improves endothelial function in patients with Type 2 diabetes mellitus and low vitamin D levels," Diabetic Medicine, 2008, volume 25, issue 3, pages 320 to 325; bibliographic record confirmed via Crossref, and the specific ergocalciferol dosing detail ("a single, large dose of ergocalciferol") corroborated via a separate indexed digest of the same study. Full text was not accessible: the publisher (Wiley) returned an access error, Unpaywall confirmed no open-access copy exists, and Europe PMC and Semantic Scholar were both blocked at the network level during this review. Sample size, exact dose, and effect size are therefore not independently confirmed and this source is disclosed, not counted as graded evidence. Separately, a 14-trial, 1,385-participant cholecalciferol-inclusive meta-analysis (Nutrition Journal) found no significant pooled effect on hemoglobin (standardized mean difference 0.01, 95% CI -0.28 to 0.29, P=0.95, I-squared=82%). Ergocalciferol was not confirmed in that meta-analysis's cohort composition. Tier C for the graded portion of this entry.

Mechanism

Proposed via hepcidin suppression (see Iron entry, shared class-level source, disclosed in Overlap map) improving iron availability for erythropoiesis; separately, and only for the disclosed-but-unverified Sugden source, a distinct vascular endothelial mechanism this review could not confirm from the primary text.

Counter-evidence held on record

Do not present ergocalciferol as reliably improving oxygen delivery, hemoglobin, or endothelial function; the one directly on-point, drug-specific human trial identified could not be independently verified, and the class-level pooled hemoglobin evidence is null.

ATP production, no ergocalciferol-specific data, class extrapolation only

Yellow — Low

See study details

No ergocalciferol-specific ATP or phosphocreatine-flux study was located; the only relevant evidence in this project is the same cholecalciferol human, animal, and cell-culture program cited under Mitochondrial burden, reporting proxy enzyme-activity and functional muscle measures, not direct ATP flux, making this a doubly-indirect class-level extrapolation for ergocalciferol.

Full detail and limits

What the grade means here: Mechanistic plausibility only (Tier B), or class extrapolation (Tier C) with no drug-specific human status data; also used for context flags and interactions running the other direction. YELLOW, class extrapolation, proxy measures only

Limits on what this shows

  • Key negative/null findings: No direct ATP or phosphocreatine-recovery flux assay was located for either ergocalciferol or, independently, cholecalciferol in this review.
  • At-risk subgroups: Not established for ergocalciferol.
  • Counter-evidence on record: None found contradicting the direction; the limitation is entirely one of measurement directness and drug-specificity, not a competing finding.

Regulatory status

Not addressed in the ergocalciferol label reviewed.

Population evidence

Same Communications Biology 2022 source as the Mitochondrial burden entry (see Overlap map): cholecalciferol-treated human trial showing lean mass and grip strength gains, plus cell-culture citrate synthase activity increases (29 to 37%) with 1,25(OH)2 vitamin D3. Ergocalciferol was not administered in this program. Tier C for ergocalciferol.

Mechanism

Proposed via the same PGC1alpha/mitochondrial biogenesis pathway cited under Mitochondrial burden; citrate synthase and electron transport chain activity are accepted proxies for oxidative ATP-generating capacity, not a direct ATP measurement, for either vitamin D form.

Counter-evidence held on record

Do not present ergocalciferol as directly boosting cellular ATP output; no drug-specific data exists at any tier, and even the class-level proxy data is not a direct energy-flux measurement.

Claims checked and not supported

These circulate online for this medication. They are listed here only so they can be answered, never as findings, and they are not graded.

A claim with no supporting evidence is not necessarily disproven. Where evidence actually argues against a claim, that is stated below.

  • Ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) are interchangeable, equally potent forms of vitamin D, so the choice between them makes no practical difference

    Where it comes from: General wellness and supplement-marketing content treating "vitamin D" as a single undifferentiated category, and historical pharmacy substitution practices treating IU-for-IU dosing as equivalent

    Why it fails: A head-to-head randomized trial at equal 50,000 IU once-weekly prescription-strength doses in chronic kidney disease patients found cholecalciferol produced a significantly greater rise in total 25-hydroxyvitamin D at 12 weeks than ergocalciferol (45.0 v. 30.7 ng/ml, P<0.01), and NIH's Office of Dietary Supplements states plainly that most evidence indicates vitamin D3 increases and sustains serum 25(OH)D levels to a greater extent than vitamin D2. The same head-to-head trial found ergocalciferol dosing significantly suppressed the body's own endogenous 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 subfractions, a genuine pharmacodynamic difference, not a marketing distinction. The drug's own comparative trial data directly contradicts an unqualified interchangeability claim.

  • High-dose ergocalciferol carries no meaningful toxicity risk because it is a natural vitamin, not a synthetic drug

    Where it comes from: General wellness and supplement-marketing framing of vitamin D as inherently benign because it occurs naturally

    Why it fails: The FDA-regulated ergocalciferol label explicitly states "the range between therapeutic and toxic doses is narrow," lists hypercalcemia and hypervitaminosis D as contraindications, and requires calcium and phosphorus monitoring at least every two weeks plus monthly bone x-ray until stabilization; this review also identified, via bibliographic search, multiple published case reports specifically describing ergocalciferol-induced hypercalcemia and toxicity, including one in an infant following erroneous dosing. The drug's own regulatory record and case-report literature directly contradict the "risk-free because natural" framing.

  • Vitamin D2 supplementation reliably raises hemoglobin and treats low energy or fatigue by improving blood oxygen-carrying capacity

    Where it comes from: General wellness content linking any form of vitamin D repletion to improved energy and blood health, without distinguishing D2 from D3 or citing drug-specific evidence

    Why it fails: No ergocalciferol-specific hemoglobin or energy-outcome trial was located in this review at all, and the best available class-level evidence, a 14-trial, 1,385-participant meta-analysis of vitamin D supplementation broadly, found no significant overall effect on hemoglobin (P=0.95). There is no drug-specific evidence to support this claim for ergocalciferol, and even the closest class-level evidence contradicts an unqualified version of it.

All references used above
  1. ERGOCALCIFEROL 1.25 mg (50,000 units) capsule, liquid filled, full labeling — FDA-registered labeling via DailyMed (Banner Life Sciences LLC). Cited for indications, contraindications, narrow therapeutic-to-toxic dose range warning, monitoring requirements (calcium/phosphorus every two weeks, monthly bone x-ray), thiazide interaction, mineral oil interaction, onset lag, and hypercalcemia toxicity persistence.
  2. DailyMed search listing, "ergocalciferol" — Used to identify the range of currently marketed generic ergocalciferol 50,000 IU manufacturers (Alembic, Chartwell RX, Banner Life Sciences, Bionpharma, SigmaPharm, Epic Pharma, Torrent, Virtus) cited in the masthead brands chip; 57 total label results confirmed no actively marketed proprietary brand name was identified in this search.
  3. Ergocalciferol, Wikipedia — Cited for ATC code confirmation (A11CC01), the CYP2R1/CYP27B1/CYP24A1 metabolic pathway and the confirmed distinction that CYP27A1 does not perform ergocalciferol's 25-hydroxylation, the lower vitamin D binding protein affinity of D2 metabolites versus D3, ercalcitriol's vitamin D receptor affinity similar to calcitriol, and the general D3-favors-potency meta-analytic conclusion.
  4. Ergocalciferol, professional pharmacology monograph — drugs.com. Cited for absorption bioavailability (about 80%), chylomicron/vitamin D binding protein distribution, breast milk distribution of 25-hydroxyergocalciferol, hepatic 25-hydroxylase metabolism, and the full drug interaction list (cholestyramine, colestipol, mineral oil, phenobarbital, phenytoin, thiazides, cardiac glycosides) and hypervitaminosis-D adverse reaction list including anemia.
  5. NIH Office of Dietary Supplements, Vitamin D Health Professional Fact Sheet — Cited for the Tolerable Upper Intake Level (100 mcg, 4,000 IU per day for adults), the toxicity-associated serum 25(OH)D threshold (above roughly 150 ng/mL), and the direct comparative-potency statement that most evidence indicates cholecalciferol raises and sustains serum 25(OH)D to a greater extent than ergocalciferol.
  6. NIH Office of Dietary Supplements, Calcium Health Professional Fact Sheet — Cited for the calcium Tolerable Upper Intake Level by age group and vitamin D's role in intestinal calcium absorption.
  7. NIH Office of Dietary Supplements, Magnesium Health Professional Fact Sheet — Cited for the supplemental magnesium Tolerable Upper Intake Level (350 mg per day for adults) and magnesium's general regulatory role in PTH and active vitamin D concentrations.
  8. NIH Office of Dietary Supplements, Vitamin K Health Professional Fact Sheet — Cited for confirmation no Tolerable Upper Intake Level has been established for vitamin K, Adequate Intake values, and the matrix Gla protein/vascular calcification mechanism.
  9. NIH Office of Dietary Supplements, Iron Health Professional Fact Sheet — Cited for the iron Tolerable Upper Intake Level (45 mg per day for adults) and hepcidin's role as the key regulator of iron absorption; confirmed no mention of a vitamin D interaction.
  10. NIH Office of Dietary Supplements, Copper Health Professional Fact Sheet — Cited for the copper Tolerable Upper Intake Level (10,000 mcg per day for adults) and confirmation that copper has no known clinically relevant medication interactions, with no vitamin D interaction mentioned; used to support the Copper entry's ungraded status.
  11. Wetmore, J.B., Kimber, C., Mahnken, J.D., Stubbs, J.R. "Cholecalciferol v. ergocalciferol for 25-hydroxyvitamin D (25(OH)D) repletion in chronic kidney disease." British Journal of Nutrition, 2016. — Randomized, investigator-blinded, two-arm trial, n=44, non-dialysis CKD stages 3 to 5, ergocalciferol 50,000 IU v. cholecalciferol 50,000 IU orally once weekly for 12 weeks plus 6-week observation. Ergocalciferol directly administered. Tier A. Full text read via open-access Cambridge Core PDF. Source for the Calcium entry's bounding null hypercalcemia finding, the PK basis comparative-potency data, and the D2-specific endogenous D3-subfraction suppression finding.
  12. Gallo, S., Phan, A., Vanstone, C.A., Rodd, C., Weiler, H.A. "The Change in Plasma 25-Hydroxyvitamin D Did Not Differ between Breast-Fed Infants That Received a Daily Supplement of Ergocalciferol or Cholecalciferol for 3 Months." Journal of Nutrition, 2013. — Bibliographic record confirmed via Crossref (title, authors, journal, DOI). Ergocalciferol-specific, infant cohort. Full text not opened during this review; disclosed for transparency, not counted as independent graded evidence.Full text could not be opened within this review's remaining tooling access; bibliographic details only.
  13. Glendenning, P., Chew, G.T., Seymour, H.M., et al. "Serum 25-hydroxyvitamin D levels in vitamin D-insufficient hip fracture patients after supplementation with ergocalciferol and cholecalciferol." Bone, 2009. — Bibliographic record confirmed via Crossref. Ergocalciferol-specific, hip fracture cohort. Unpaywall confirmed closed access, no repository copy. Full text not opened; disclosed for transparency only.Full text could not be opened: closed access per Unpaywall, no open-access location found.
  14. Fisk, C.M., Theobald, H.E., Sanders, T.A.B. "Fortified Malted Milk Drinks Containing Low-Dose Ergocalciferol and Cholecalciferol Do Not Differ in Their Capacity to Raise Serum 25-Hydroxyvitamin D Concentrations." Journal of Nutrition, 2012. — Bibliographic record confirmed via Crossref. Ergocalciferol-specific, low-dose fortification cohort. Full text not opened during this review; disclosed for transparency only, corroborates the general D2/D3 near-equivalence-at-low-dose literature referenced in the PK basis without being independently graded.Full text could not be opened within this review's remaining tooling access; bibliographic details only.
  15. Sugden, J.A., Davies, J.I., Witham, M.D., Morris, A.D., Struthers, A.D. "Vitamin D improves endothelial function in patients with Type 2 diabetes mellitus and low vitamin D levels." Diabetic Medicine, 2008;25(3):320-325. — Bibliographic record confirmed via Crossref; ergocalciferol dosing detail ("a single, large dose of ergocalciferol") corroborated via a separate indexed digest citation. Cited, disclosed but not independently graded, in the Oxygen delivery/utilization entry.Full text could not be opened: Wiley returned an access error (403) and Unpaywall confirmed no open-access copy exists.
  16. Stephenson, D.W., Peiris, A.N. "The Lack of Vitamin D Toxicity with Megadose of Daily Ergocalciferol (D2) Therapy: A Case Report and Literature Review." Southern Medical Journal, 2009;102(7):765-768. — Bibliographic record confirmed via Crossref. Ergocalciferol-specific case report and literature review, directly on point for the Calcium entry's counter-evidence. Full text not opened; disclosed for transparency, not counted as independent graded evidence.Full text could not be opened: Unpaywall confirmed closed access, no repository copy; the publisher landing page was not independently retried after the first access error.
  17. "Ergocalciferol, Vitamin D toxicity: case report." Reactions Weekly, 2011. — Bibliographic record confirmed via Crossref. Ergocalciferol-specific adverse-event case digest. Full text not opened; disclosed for transparency in the Calcium entry only, not counted as independent graded evidence.Full text could not be opened within this review's remaining tooling access; bibliographic details only.
  18. "Ergocalciferol, Vitamin D toxicity following incorrect dose: case report." Reactions Weekly, 2019. — Bibliographic record confirmed via Crossref. Ergocalciferol-specific adverse-event case digest. Full text not opened; disclosed for transparency in the Calcium entry only.Full text could not be opened: repeated gateway-level rejections on the Springer link during this review.
  19. "Colecalciferol/ergocalciferol, Hypervitaminosis-D and vitamin D toxicity following overdose: case report." Reactions Weekly, 2022. — Bibliographic record confirmed via Crossref. Combined D2/D3 overdose case digest, ergocalciferol named as one of the agents involved. Full text not opened; disclosed for transparency in the Calcium entry only.Full text could not be opened within this review's remaining tooling access; bibliographic details only.
  20. "Ergocalciferol overdose, Hypercalcaemia and nephrocalcinosis due to vitamin D2 intoxication following erroneous administration in an infant: case report." Reactions Weekly, 2012. — Bibliographic record confirmed via Crossref. Ergocalciferol-specific pediatric adverse-event case digest, cited for the infant at-risk subgroup and monitoring panel entry. Full text not opened; disclosed for transparency, not counted as independent graded evidence.Full text could not be opened within this review's remaining tooling access; bibliographic details only.
  21. Harrington, D.D. "Acute vitamin D2 (ergocalciferol) toxicosis in horses: Case report and experimental studies." Journal of the American Veterinary Medical Association, 1982. — Bibliographic record confirmed via Crossref. Excluded from this dossier's graded evidence on cohort/species grounds (equine, not human); noted only to disclose it was found and deliberately not used.Excluded: non-human (equine) cohort, outside this protocol's human cohort-test scope.
  22. "Vitamin D status modulates mitochondrial oxidative capacities in skeletal muscle: role in sarcopenia." Communications Biology, 2022. — Cholecalciferol-specific human RCT (n=115), rat depletion model, and cell-culture study, read via this project's cholecalciferol dossier sourcing. Ergocalciferol was not in this cohort. Tier C class-level source for the Mitochondrial burden and ATP production entries in this dossier.
  23. "The effect of vitamin D supplementation on oxidative stress parameters: A systematic review and meta-analysis of clinical trials." ScienceDirect. — Pooled vitamin D meta-analysis, not confirmed as ergocalciferol-inclusive, read via this project's cholecalciferol dossier sourcing. Tier C class-level source for the Oxidative stress entry.
  24. "The Effects of Vitamin D Supplementation on Metabolic and Oxidative Stress Markers in Patients With Type 2 Diabetes: A 6-Month Follow Up Randomized Controlled Study." Frontiers in Endocrinology, 2021. — Cholecalciferol-specific RCT (n=130), read via this project's cholecalciferol dossier sourcing. Ergocalciferol not in cohort. Tier C class-level source for the Oxidative stress entry's null finding.
  25. "High-dose vitamin D3 reduces circulating hepcidin concentrations: A pilot, randomized, double-blind, placebo-controlled trial in healthy adults." Clinical Nutrition. — Cholecalciferol-specific RCT (n=28), read via this project's cholecalciferol dossier sourcing. Ergocalciferol not in cohort. Tier C class-level source for the Iron entry.
  26. "The effect of vitamin D supplementation on hemoglobin concentration: a systematic review and meta-analysis." Nutrition Journal. — Pooled meta-analysis (14 RCTs, n=1,385), read via this project's cholecalciferol dossier sourcing, not confirmed as ergocalciferol-inclusive. Tier C class-level source for the Iron and Oxygen delivery/utilization entries.
  27. "Randomized control trial of moderate dose vitamin D alters microbiota stability and metabolite networks in healthy adults." Microbiology Spectrum. — Cholecalciferol-specific RCT (n=41 completers), read via this project's cholecalciferol dossier sourcing. Ergocalciferol not in cohort. Tier C class-level source for the Gut microbiome risk entry.
  28. "Effects of vitamin K2 and D supplementation on coronary artery disease in men: A randomized controlled trial" (AVADEC trial substudy). JACC: Advances. — Cholecalciferol/K2 combination RCT (n=304), read via this project's cholecalciferol dossier sourcing. Ergocalciferol not in cohort. Tier C class-level source for the Vitamin K entry.
  29. "Magnesium status and supplementation influence vitamin D status and metabolism: results from a randomized trial." American Journal of Clinical Nutrition. — Magnesium-intervention RCT (n=180) measuring D3 metabolites, read via this project's cholecalciferol dossier sourcing. Neither cholecalciferol nor ergocalciferol was the administered intervention. Tier C class-level source for the Magnesium entry.