Ergocalciferol / vitamin D2

cross_nutrient

false

experimental_model

Human bone-clinic cohort and ex-vivo monocytes in 10% autologous serum

exposure

D2 treatment and paired circulating hCAP assay in the bone-clinic cohort.

limitations

Circulating protein and stimulated local transcription are different readouts, so this is not a contradiction.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

A better local cell response did not translate into a higher circulating protein measurement.

primary_references

[adams2009] Vitamin d-directed rheostatic regulation of monocyte antibacterial responses. (2009). https://pubmed.ncbi.nlm.nih.gov/19299728/ DOI: 10.4049/jimmunol.0803736

tissue_or_cell_type

Human serum

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1022–1033

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human bone-clinic cohort and ex-vivo monocytes in 10% autologous serum · source_derived_draft · unverified_draft

### vd-adams-circulating-hcap-null The patient D2 supplementation course did not change circulating hCAP concentration, despite improved serum support for the ex-vivo transcript response. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A better local cell response did not translate into a higher circulating protein measurement. organism: Homo sapiens tissue_or_cell_type: Human serum experimental_model: Human bone-clinic cohort and ex-vivo monocytes in 10% autologous serum limitations: Circulating protein and stimulated local transcription are different readouts, so this is not a contradiction. exposure: D2 treatment and paired circulating hCAP assay in the bone-clinic cohort. cross_nutrient: false [adams2009] Vitamin d-directed rheostatic regulation of monocyte antibacterial responses. (2009). https://pubmed.ncbi.nlm.nih.gov/19299728/ DOI: 10.4049/jimmunol.0803736

cross_nutrient

false

experimental_model

Human bone-clinic cohort and ex-vivo monocytes in 10% autologous serum

exposure

D2 50, 000 IU twice weekly 5 weeks in low-status patients; paired serum used for ex-vivo assays.

limitations

Before/after serum comparison; no randomized D2/D3 head-to-head or demonstrated reduction of infections.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

D2 treatment changed serum support for a local cell response.

primary_references

[adams2009] Vitamin d-directed rheostatic regulation of monocyte antibacterial responses. (2009). https://pubmed.ncbi.nlm.nih.gov/19299728/ DOI: 10.4049/jimmunol.0803736

tissue_or_cell_type

Patient serum and ex-vivo monocytes

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1009–1020

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human bone-clinic cohort and ex-vivo monocytes in 10% autologous serum · source_derived_draft · unverified_draft

### vd-adams-d2-serum-rescue Serum collected after D2 treatment of low-status patients better supported TLR-triggered monocyte hCAP expression ex vivo. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: D2 treatment changed serum support for a local cell response. organism: Homo sapiens tissue_or_cell_type: Patient serum and ex-vivo monocytes experimental_model: Human bone-clinic cohort and ex-vivo monocytes in 10% autologous serum limitations: Before/after serum comparison; no randomized D2/D3 head-to-head or demonstrated reduction of infections. exposure: D2 50, 000 IU twice weekly 5 weeks in low-status patients; paired serum used for ex-vivo assays. cross_nutrient: false [adams2009] Vitamin d-directed rheostatic regulation of monocyte antibacterial responses. (2009). https://pubmed.ncbi.nlm.nih.gov/19299728/ DOI: 10.4049/jimmunol.0803736

analysis_scope

Within-group baseline-to-week 12 GSEA; not a randomized treatment-versus-placebo contrast.

cross_nutrient

false

experimental_model

97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women

exposure

15 micrograms/day D2 or D3 or placebo for 12 winter weeks; blood microarrays at baseline/end.

limitations

Exploratory selected trial subset; differences in baseline status, season and whole-blood cell composition may matter. Within-group significance is not a significant difference between groups; no infection endpoint.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

This was a time trend in a gene set within one study group, not proof of improved infection resistance.

primary_references

[durrant2022] Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome. (2022). https://pubmed.ncbi.nlm.nih.gov/35281034/ DOI: 10.3389/fimmu.2022.790444

tissue_or_cell_type

Whole blood

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1128–1140

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women · source_derived_draft · unverified_draft

### vd-durrant-d2-white-european-alpha The interferon-alpha response gene set was negatively enriched at week 12 versus baseline within the white-European D2 group (GSEA adjusted P≤ 0.05). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This was a time trend in a gene set within one study group, not proof of improved infection resistance. organism: Homo sapiens tissue_or_cell_type: Whole blood experimental_model: 97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women limitations: Exploratory selected trial subset; differences in baseline status, season and whole-blood cell composition may matter. Within-group significance is not a significant difference between groups; no infection endpoint. exposure: 15 micrograms/day D2 or D3 or placebo for 12 winter weeks; blood microarrays at baseline/end. cross_nutrient: false analysis_scope: Within-group baseline-to-week 12 GSEA; not a randomized treatment-versus-placebo contrast. [durrant2022] Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome. (2022). https://pubmed.ncbi.nlm.nih.gov/35281034/ DOI: 10.3389/fimmu.2022.790444

analysis_scope

Within-group baseline-to-week 12 GSEA; not a randomized treatment-versus-placebo contrast.

cross_nutrient

false

experimental_model

97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women

exposure

15 micrograms/day D2 or D3 or placebo for 12 winter weeks; blood microarrays at baseline/end.

limitations

Exploratory selected trial subset; differences in baseline status, season and whole-blood cell composition may matter. Within-group significance is not a significant difference between groups; no infection endpoint.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

This was a time trend in a gene set within one study group, not proof of improved infection resistance.

primary_references

[durrant2022] Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome. (2022). https://pubmed.ncbi.nlm.nih.gov/35281034/ DOI: 10.3389/fimmu.2022.790444

tissue_or_cell_type

Whole blood

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1142–1154

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women · source_derived_draft · unverified_draft

### vd-durrant-d2-white-european-gamma The interferon-gamma response gene set was negatively enriched at week 12 versus baseline within the white-European D2 group (GSEA adjusted P≤ 0.05). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: This was a time trend in a gene set within one study group, not proof of improved infection resistance. organism: Homo sapiens tissue_or_cell_type: Whole blood experimental_model: 97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women limitations: Exploratory selected trial subset; differences in baseline status, season and whole-blood cell composition may matter. Within-group significance is not a significant difference between groups; no infection endpoint. exposure: 15 micrograms/day D2 or D3 or placebo for 12 winter weeks; blood microarrays at baseline/end. cross_nutrient: false analysis_scope: Within-group baseline-to-week 12 GSEA; not a randomized treatment-versus-placebo contrast. [durrant2022] Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome. (2022). https://pubmed.ncbi.nlm.nih.gov/35281034/ DOI: 10.3389/fimmu.2022.790444

cross_nutrient

false

experimental_model

Two randomized single-dose experiments; 100 volunteers, 97 analyzed

exposure

Study 1: one 50, 000 IU oral D2 dose versus placebo.

limitations

No direct enzyme-flux assay. Reciprocal fraction changes are not proof that D2 is toxic or that net total vitamin D falls.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

A large D2 dose lowered the measured D3-derived fraction in this experiment.

primary_references

[hammami2019] Vitamin-D2 treatment-associated decrease in 25(OH)D3 level is a reciprocal phenomenon: a randomized controlled trial. (2019). https://pubmed.ncbi.nlm.nih.gov/30658603/ DOI: 10.1186/s12902-019-0337-8

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1405–1416

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Two randomized single-dose experiments; 100 volunteers, 97 analyzed · source_derived_draft · unverified_draft

### vd-hammami-d2-decreases-d3 At day 28, the D2 arm showed a 13.2 nmol/L greater decline in 25(OH)D3 than placebo (95% CI9.7–16.6). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A large D2 dose lowered the measured D3-derived fraction in this experiment. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Two randomized single-dose experiments; 100 volunteers, 97 analyzed limitations: No direct enzyme-flux assay. Reciprocal fraction changes are not proof that D2 is toxic or that net total vitamin D falls. exposure: Study 1: one 50, 000 IU oral D2 dose versus placebo. cross_nutrient: false [hammami2019] Vitamin-D2 treatment-associated decrease in 25(OH)D3 level is a reciprocal phenomenon: a randomized controlled trial. (2019). https://pubmed.ncbi.nlm.nih.gov/30658603/ DOI: 10.1186/s12902-019-0337-8

cross_nutrient

false

experimental_model

Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks

exposure

D2 or D3 50, 000 IU orally each week for 12 weeks.

limitations

This weekly regimen and marker response do not establish a universal conversion factor or superiority for every clinical endpoint. This is vitamer-specific content, not the disputed total-fat unit in the abstract.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The administered form was also measured in fat tissue.

primary_references

[heaney2011] Vitamin D(3) is more potent than vitamin D(2) in humans. (2011). https://pubmed.ncbi.nlm.nih.gov/21177785/ DOI: 10.1210/jc.2010-2230

tissue_or_cell_type

Subcutaneous adipose tissue

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1327–1338

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks · source_derived_draft · unverified_draft

### vd-heaney-fat-d2 Subcutaneous adipose content of the administered D2 increased by 50 micrograms/kg. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The administered form was also measured in fat tissue. organism: Homo sapiens tissue_or_cell_type: Subcutaneous adipose tissue experimental_model: Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks limitations: This weekly regimen and marker response do not establish a universal conversion factor or superiority for every clinical endpoint. This is vitamer-specific content, not the disputed total-fat unit in the abstract. exposure: D2 or D3 50, 000 IU orally each week for 12 weeks. cross_nutrient: false [heaney2011] Vitamin D(3) is more potent than vitamin D(2) in humans. (2011). https://pubmed.ncbi.nlm.nih.gov/21177785/ DOI: 10.1210/jc.2010-2230

cross_nutrient

false

experimental_model

Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks

exposure

Daily D2 1000 IU, D3 1000 IU, mixed 500+500 IU or placebo; 11 winter weeks.

limitations

Small groups and biochemical endpoints; authors reported comparable responses. Daily regimen differs from single-dose and food-fortification studies.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

A fall in the D3-derived fraction was not detected in every D2 regimen.

primary_references

[holick2008] Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. (2008). https://pubmed.ncbi.nlm.nih.gov/18089691/ DOI: 10.1210/jc.2007-2308

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1288–1299

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks · source_derived_draft · unverified_draft

### vd-holick-d2-d3-fraction The D2-only daily group did not show a change in serum 25(OH)D3 over the 11-week study. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A fall in the D3-derived fraction was not detected in every D2 regimen. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks limitations: Small groups and biochemical endpoints; authors reported comparable responses. Daily regimen differs from single-dose and food-fortification studies. exposure: Daily D2 1000 IU, D3 1000 IU, mixed 500+500 IU or placebo; 11 winter weeks. cross_nutrient: false [holick2008] Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. (2008). https://pubmed.ncbi.nlm.nih.gov/18089691/ DOI: 10.1210/jc.2007-2308

cross_nutrient

false

experimental_model

Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks

exposure

Daily D2 1000 IU, D3 1000 IU, mixed 500+500 IU or placebo; 11 winter weeks.

limitations

Small groups and biochemical endpoints; authors reported comparable responses. Daily regimen differs from single-dose and food-fortification studies.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

Both forms increased the blood marker in this daily-dose trial.

primary_references

[holick2008] Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. (2008). https://pubmed.ncbi.nlm.nih.gov/18089691/ DOI: 10.1210/jc.2007-2308

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1262–1273

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks · source_derived_draft · unverified_draft

### vd-holick-daily-d2 Mean serum total 25(OH)D rose from 16.9 to 26.8 ng/mL with daily D2; the study reported a comparable response to D3, which rose from 19.6 to 28.9 ng/mL. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Both forms increased the blood marker in this daily-dose trial. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks limitations: Small groups and biochemical endpoints; authors reported comparable responses. Daily regimen differs from single-dose and food-fortification studies. exposure: Daily D2 1000 IU, D3 1000 IU, mixed 500+500 IU or placebo; 11 winter weeks. cross_nutrient: false [holick2008] Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. (2008). https://pubmed.ncbi.nlm.nih.gov/18089691/ DOI: 10.1210/jc.2007-2308

cross_nutrient

false

experimental_model

52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months

exposure

Four oral 2.5 mg D2 or D3 bolus doses over 4 months.

limitations

Metabolite-to-parent ratios integrate production, binding, distribution and clearance; they are not an isolated CYP activity assay.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The active-D3 to precursor ratio also fell under this bolus regimen.

primary_references

[martineau2019] Differential Effects of Oral Boluses of Vitamin D2 vs Vitamin D3 on Vitamin D Metabolism: A Randomized Controlled Trial. (2019). https://pubmed.ncbi.nlm.nih.gov/31199458/ DOI: 10.1210/jc.2019-00207

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1444–1455

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months · source_derived_draft · unverified_draft

### vd-martineau-1alpha-ratio After D2, the mean 1, 25(OH)2D3: 25(OH)D3 ratio decreased and was lower than after D3. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The active-D3 to precursor ratio also fell under this bolus regimen. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: 52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months limitations: Metabolite-to-parent ratios integrate production, binding, distribution and clearance; they are not an isolated CYP activity assay. exposure: Four oral 2.5 mg D2 or D3 bolus doses over 4 months. cross_nutrient: false [martineau2019] Differential Effects of Oral Boluses of Vitamin D2 vs Vitamin D3 on Vitamin D Metabolism: A Randomized Controlled Trial. (2019). https://pubmed.ncbi.nlm.nih.gov/31199458/ DOI: 10.1210/jc.2019-00207

cross_nutrient

false

experimental_model

52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months

exposure

Four oral 2.5 mg D2 or D3 bolus doses over 4 months.

limitations

Metabolite-to-parent ratios integrate production, binding, distribution and clearance; they are not an isolated CYP activity assay.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

Both groups showed a catabolic-ratio increase; the between-form difference was not detected.

primary_references

[martineau2019] Differential Effects of Oral Boluses of Vitamin D2 vs Vitamin D3 on Vitamin D Metabolism: A Randomized Controlled Trial. (2019). https://pubmed.ncbi.nlm.nih.gov/31199458/ DOI: 10.1210/jc.2019-00207

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1457–1468

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months · source_derived_draft · unverified_draft

### vd-martineau-24-ratio The 24R, 25(OH)2D3: 25(OH)D3 ratio rose within both D2 and D3 groups, but their postsupplementation ratios did not differ significantly. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Both groups showed a catabolic-ratio increase; the between-form difference was not detected. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: 52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months limitations: Metabolite-to-parent ratios integrate production, binding, distribution and clearance; they are not an isolated CYP activity assay. exposure: Four oral 2.5 mg D2 or D3 bolus doses over 4 months. cross_nutrient: false [martineau2019] Differential Effects of Oral Boluses of Vitamin D2 vs Vitamin D3 on Vitamin D Metabolism: A Randomized Controlled Trial. (2019). https://pubmed.ncbi.nlm.nih.gov/31199458/ DOI: 10.1210/jc.2019-00207

cross_nutrient

false

experimental_model

52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months

exposure

Four oral 2.5 mg D2 or D3 bolus doses over 4 months.

limitations

Metabolite-to-parent ratios integrate production, binding, distribution and clearance; they are not an isolated CYP activity assay.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The metabolite-to-parent ratio changed, suggesting altered handling of D3.

primary_references

[martineau2019] Differential Effects of Oral Boluses of Vitamin D2 vs Vitamin D3 on Vitamin D Metabolism: A Randomized Controlled Trial. (2019). https://pubmed.ncbi.nlm.nih.gov/31199458/ DOI: 10.1210/jc.2019-00207

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1431–1442

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months · source_derived_draft · unverified_draft

### vd-martineau-25-ratio After D2, the mean 25(OH)D3: D3 ratio decreased and was lower than after D3. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The metabolite-to-parent ratio changed, suggesting altered handling of D3. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: 52-person metabolite-profile subset of a 340-person randomized trial; four 2.5 mg oral D2/D3 boluses over 4 months limitations: Metabolite-to-parent ratios integrate production, binding, distribution and clearance; they are not an isolated CYP activity assay. exposure: Four oral 2.5 mg D2 or D3 bolus doses over 4 months. cross_nutrient: false [martineau2019] Differential Effects of Oral Boluses of Vitamin D2 vs Vitamin D3 on Vitamin D Metabolism: A Randomized Controlled Trial. (2019). https://pubmed.ncbi.nlm.nih.gov/31199458/ DOI: 10.1210/jc.2019-00207

cross_nutrient

false

evidence_location

Primary Results: Photoproduction of previtamin D2 and its conversion to vitamin D2; Figures 2-5.

experimental_model

Mushroom-versus-solution HPLC time course

exposure

Post-irradiation time course at 25 C; approximately half converted after 11.5 hours in mushrooms.

limitations

Matrix and temperature affect rate; no metabolic activation enzyme is implied.

nutrient

Vitamin D2 and D3 · Vitamin D2 and D3

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Agaricus bisporus

plain_language

The fungal photoproduct rearranges into vitamin D2.

primary_references

[keegan2013] Photobiology of vitamin D in mushrooms and its bioavailability in humans. (2013). https://pubmed.ncbi.nlm.nih.gov/24494050/ DOI: 10.4161/derm.23321

tissue_or_cell_type

mushroom tissue

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 151–164

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Mushroom-versus-solution HPLC time course · source_derived_draft · unverified_draft

### vd-act-previtamin-d2-isomerization Previtamin D2 generated in irradiated mushrooms converted thermally to ergocalciferol; mushroom conversion was faster than in methanol in the compared preparations. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The fungal photoproduct rearranges into vitamin D2. organism: Agaricus bisporus tissue_or_cell_type: mushroom tissue experimental_model: Mushroom-versus-solution HPLC time course limitations: Matrix and temperature affect rate; no metabolic activation enzyme is implied. exposure: Post-irradiation time course at 25 C; approximately half converted after 11.5 hours in mushrooms. cross_nutrient: false evidence_location: Primary Results: Photoproduction of previtamin D2 and its conversion to vitamin D2; Figures 2-5. nutrient: Vitamin D2 and D3 [keegan2013] Photobiology of vitamin D in mushrooms and its bioavailability in humans. (2013). https://pubmed.ncbi.nlm.nih.gov/24494050/ DOI: 10.4161/derm.23321

cross_nutrient

false

evidence_location

Primary abstract, substrate product positions and kinetic comparison.

experimental_model

Recombinant human CYP27A1 product identification

exposure

D2 incubation; concentration/time not reported in retrieved abstract.

limitations

D2 C24/C27 hydroxylation must not be mislabeled as C25 activation or assumed to be the main route in vivo.

nutrient

Vitamin D2 and D3 · Vitamin D2 and D3

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens protein

plain_language

CYP27A1 modifies D2 at carbon 24.

primary_references

[shinkyo2004] Metabolism of vitamin D by human microsomal CYP2R1. (2004). https://pubmed.ncbi.nlm.nih.gov/15465040/ DOI: 10.1016/j.bbrc.2004.09.073

tissue_or_cell_type

mitochondrial enzyme preparation

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 332–345

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human CYP27A1 product identification · source_derived_draft · unverified_draft

### vd-act-cyp27a1-d2-c24 Human CYP27A1 hydroxylated ergocalciferol at C24 in the reported D2 substrate analysis. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: CYP27A1 modifies D2 at carbon 24. organism: Homo sapiens protein tissue_or_cell_type: mitochondrial enzyme preparation experimental_model: Recombinant human CYP27A1 product identification limitations: D2 C24/C27 hydroxylation must not be mislabeled as C25 activation or assumed to be the main route in vivo. exposure: D2 incubation; concentration/time not reported in retrieved abstract. cross_nutrient: false evidence_location: Primary abstract, substrate product positions and kinetic comparison. nutrient: Vitamin D2 and D3 [shinkyo2004] Metabolism of vitamin D by human microsomal CYP2R1. (2004). https://pubmed.ncbi.nlm.nih.gov/15465040/ DOI: 10.1016/j.bbrc.2004.09.073

cross_nutrient

false

evidence_location

Primary abstract, substrate product positions and kinetic comparison.

experimental_model

Recombinant human CYP27A1 product identification

exposure

D2 incubation; concentration/time not reported in retrieved abstract.

limitations

D2 C24/C27 hydroxylation must not be mislabeled as C25 activation or assumed to be the main route in vivo.

nutrient

Vitamin D2 and D3 · Vitamin D2 and D3

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens protein

plain_language

CYP27A1 modifies D2 at carbon 27.

primary_references

[shinkyo2004] Metabolism of vitamin D by human microsomal CYP2R1. (2004). https://pubmed.ncbi.nlm.nih.gov/15465040/ DOI: 10.1016/j.bbrc.2004.09.073

tissue_or_cell_type

mitochondrial enzyme preparation

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 347–360

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human CYP27A1 product identification · source_derived_draft · unverified_draft

### vd-act-cyp27a1-d2-c27 Human CYP27A1 hydroxylated ergocalciferol at C27 in the reported D2 substrate analysis. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: CYP27A1 modifies D2 at carbon 27. organism: Homo sapiens protein tissue_or_cell_type: mitochondrial enzyme preparation experimental_model: Recombinant human CYP27A1 product identification limitations: D2 C24/C27 hydroxylation must not be mislabeled as C25 activation or assumed to be the main route in vivo. exposure: D2 incubation; concentration/time not reported in retrieved abstract. cross_nutrient: false evidence_location: Primary abstract, substrate product positions and kinetic comparison. nutrient: Vitamin D2 and D3 [shinkyo2004] Metabolism of vitamin D by human microsomal CYP2R1. (2004). https://pubmed.ncbi.nlm.nih.gov/15465040/ DOI: 10.1016/j.bbrc.2004.09.073

cross_nutrient

false

evidence_location

Primary abstract, substrate product positions and kinetic comparison.

experimental_model

Recombinant human enzyme product identification

exposure

D2 substrate incubations; detailed concentration/time not available in abstract.

limitations

A shared enzyme does not by itself prove equal long-term serum responses to all D2 and D3 dosing regimens.

nutrient

Vitamin D2 and D3 · Vitamin D2 and D3

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens protein

plain_language

The same first-step enzyme also activates D2.

primary_references

[shinkyo2004] Metabolism of vitamin D by human microsomal CYP2R1. (2004). https://pubmed.ncbi.nlm.nih.gov/15465040/ DOI: 10.1016/j.bbrc.2004.09.073

tissue_or_cell_type

microsomal enzyme preparation

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 302–315

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Recombinant human enzyme product identification · source_derived_draft · unverified_draft

### vd-act-cyp2r1-d2 Recombinant human CYP2R1 hydroxylated ergocalciferol at C25 to form 25-hydroxyvitamin D2. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The same first-step enzyme also activates D2. organism: Homo sapiens protein tissue_or_cell_type: microsomal enzyme preparation experimental_model: Recombinant human enzyme product identification limitations: A shared enzyme does not by itself prove equal long-term serum responses to all D2 and D3 dosing regimens. exposure: D2 substrate incubations; detailed concentration/time not available in abstract. cross_nutrient: false evidence_location: Primary abstract, substrate product positions and kinetic comparison. nutrient: Vitamin D2 and D3 [shinkyo2004] Metabolism of vitamin D by human microsomal CYP2R1. (2004). https://pubmed.ncbi.nlm.nih.gov/15465040/ DOI: 10.1016/j.bbrc.2004.09.073

cross_nutrient

false

experimental_model

Human single-dose comparison; 20 healthy men; 28-day follow-up

exposure

One oral 50, 000-IU dose of D2 or D3; serial serum measures for 28 days.

limitations

Single 50, 000-IU dose in healthy men; biochemical response, not fracture efficacy. Model-extrapolated potency is not a universal IU conversion.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The measured difference and the extrapolated difference are separate results.

primary_references

[armas2004] Vitamin D2 is much less effective than vitamin D3 in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15531486/ DOI: 10.1210/jc.2004-0360

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1249–1260

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human single-dose comparison; 20 healthy men; 28-day follow-up · source_derived_draft · unverified_draft

### vd-armas-auc Measured incremental 25(OH)D AUC through day 28 was 204.7 ng·day/mL for D3 versus 60.2 for D2 (P<0.002); the reported 9.5: 1 ratio instead came from extrapolation to infinite time. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The measured difference and the extrapolated difference are separate results. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Human single-dose comparison; 20 healthy men; 28-day follow-up limitations: Single 50, 000-IU dose in healthy men; biochemical response, not fracture efficacy. Model-extrapolated potency is not a universal IU conversion. exposure: One oral 50, 000-IU dose of D2 or D3; serial serum measures for 28 days. cross_nutrient: false [armas2004] Vitamin D2 is much less effective than vitamin D3 in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15531486/ DOI: 10.1210/jc.2004-0360

cross_nutrient

false

experimental_model

Human single-dose comparison; 20 healthy men; 28-day follow-up

exposure

One oral 50, 000-IU dose of D2 or D3; serial serum measures for 28 days.

limitations

Single 50, 000-IU dose in healthy men; biochemical response, not fracture efficacy. Model-extrapolated potency is not a universal IU conversion.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The two forms entered the circulation similarly in this single-dose experiment.

primary_references

[armas2004] Vitamin D2 is much less effective than vitamin D3 in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15531486/ DOI: 10.1210/jc.2004-0360

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1223–1234

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human single-dose comparison; 20 healthy men; 28-day follow-up · source_derived_draft · unverified_draft

### vd-armas-parent-appearance The administered D2 and D3 produced similar initial rises in their respective parent calciferol serum concentrations. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The two forms entered the circulation similarly in this single-dose experiment. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Human single-dose comparison; 20 healthy men; 28-day follow-up limitations: Single 50, 000-IU dose in healthy men; biochemical response, not fracture efficacy. Model-extrapolated potency is not a universal IU conversion. exposure: One oral 50, 000-IU dose of D2 or D3; serial serum measures for 28 days. cross_nutrient: false [armas2004] Vitamin D2 is much less effective than vitamin D3 in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15531486/ DOI: 10.1210/jc.2004-0360

cross_nutrient

false

experimental_model

Human single-dose comparison; 20 healthy men; 28-day follow-up

exposure

One oral 50, 000-IU dose of D2 or D3; serial serum measures for 28 days.

limitations

Single 50, 000-IU dose in healthy men; biochemical response, not fracture efficacy. Model-extrapolated potency is not a universal IU conversion.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

Similar early responses did not mean equally long-lasting blood-level responses.

primary_references

[armas2004] Vitamin D2 is much less effective than vitamin D3 in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15531486/ DOI: 10.1210/jc.2004-0360

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1236–1247

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Human single-dose comparison; 20 healthy men; 28-day follow-up · source_derived_draft · unverified_draft

### vd-armas-total25-timecourse Initial total 25(OH)D rises were similar through day 3; D3-associated levels peaked at day 14 while the D2-associated level had returned to baseline by then. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: Similar early responses did not mean equally long-lasting blood-level responses. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Human single-dose comparison; 20 healthy men; 28-day follow-up limitations: Single 50, 000-IU dose in healthy men; biochemical response, not fracture efficacy. Model-extrapolated potency is not a universal IU conversion. exposure: One oral 50, 000-IU dose of D2 or D3; serial serum measures for 28 days. cross_nutrient: false [armas2004] Vitamin D2 is much less effective than vitamin D3 in humans. (2004). https://pubmed.ncbi.nlm.nih.gov/15531486/ DOI: 10.1210/jc.2004-0360

cross_nutrient

false

experimental_model

97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women

exposure

15 micrograms/day D2 or D3 or placebo for 12 winter weeks; blood microarrays at baseline/end.

limitations

Exploratory selected trial subset; differences in baseline status, season and whole-blood cell composition may matter. Within-group significance is not a significant difference between groups; no infection endpoint.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The strongest direct comparisons were much less conclusive than the within-group gene-change lists.

primary_references

[durrant2022] Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome. (2022). https://pubmed.ncbi.nlm.nih.gov/35281034/ DOI: 10.3389/fimmu.2022.790444

tissue_or_cell_type

Whole blood

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1087–1098

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · 97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women · source_derived_draft · unverified_draft

### vd-durrant-direct-contrast Difference-in-difference testing found no significant probe changes in the white-European cohort or pooled D2/D3-versus-placebo analyses; five were found specifically for D3 versus placebo in the South-Asian cohort, largely driven by placebo-group changes. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The strongest direct comparisons were much less conclusive than the within-group gene-change lists. organism: Homo sapiens tissue_or_cell_type: Whole blood experimental_model: 97 participant transcriptomic subset of Tripkovic 2017; 67 white-European and 30 South-Asian women limitations: Exploratory selected trial subset; differences in baseline status, season and whole-blood cell composition may matter. Within-group significance is not a significant difference between groups; no infection endpoint. exposure: 15 micrograms/day D2 or D3 or placebo for 12 winter weeks; blood microarrays at baseline/end. cross_nutrient: false [durrant2022] Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood Transcriptome. (2022). https://pubmed.ncbi.nlm.nih.gov/35281034/ DOI: 10.3389/fimmu.2022.790444

availability_state

biomarker_context Imported condition classification; unverified.

cross_nutrient

true

experimental_model

Six-week randomized comparison in 40 infants/toddlers with 25(OH)D<20 ng/mL; all prescribed calcium

exposure

D2 2000 IU/day, D2 50, 000 IU/week or D3 2000 IU/day for 6 weeks; all also 50 mg/kg/day elemental calcium.

limitations

Small pediatric trial; D and calcium effects cannot be separated; biochemical outcomes do not establish long-term comparative safety.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

D2 could correct the low marker too in this short pediatric study.

primary_references

[gordon2008] Treatment of hypovitaminosis D in infants and toddlers. (2008). https://pubmed.ncbi.nlm.nih.gov/18413426/ DOI: 10.1210/jc.2007-2790

tissue_or_cell_type

Human circulating measurements

trigger_kind

biomarker_context Imported condition classification; unverified.

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1470–1481

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Six-week randomized comparison in 40 infants/toddlers with 25(OH)D<20 ng/mL; all prescribed calcium · source_derived_draft · unverified_draft

### vd-gordon-25-response All three regimens approximately tripled total 25(OH)D; daily D2 versus daily D3 differed by 7% with P=0.82. Condition category: biomarker_context nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: D2 could correct the low marker too in this short pediatric study. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Six-week randomized comparison in 40 infants/toddlers with 25(OH)D<20 ng/mL; all prescribed calcium limitations: Small pediatric trial; D and calcium effects cannot be separated; biochemical outcomes do not establish long-term comparative safety. exposure: D2 2000 IU/day, D2 50, 000 IU/week or D3 2000 IU/day for 6 weeks; all also 50 mg/kg/day elemental calcium. cross_nutrient: true [gordon2008] Treatment of hypovitaminosis D in infants and toddlers. (2008). https://pubmed.ncbi.nlm.nih.gov/18413426/ DOI: 10.1210/jc.2007-2790

availability_state

biomarker_context Imported condition classification; unverified.

cross_nutrient

true

experimental_model

Six-week randomized comparison in 40 infants/toddlers with 25(OH)D<20 ng/mL; all prescribed calcium

exposure

D2 2000 IU/day, D2 50, 000 IU/week or D3 2000 IU/day for 6 weeks; all also 50 mg/kg/day elemental calcium.

limitations

Small pediatric trial; D and calcium effects cannot be separated; biochemical outcomes do not establish long-term comparative safety.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The hormone response was not detectably different between these treatment groups.

primary_references

[gordon2008] Treatment of hypovitaminosis D in infants and toddlers. (2008). https://pubmed.ncbi.nlm.nih.gov/18413426/ DOI: 10.1210/jc.2007-2790

tissue_or_cell_type

Human circulating measurements

trigger_kind

biomarker_context Imported condition classification; unverified.

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1483–1494

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Six-week randomized comparison in 40 infants/toddlers with 25(OH)D<20 ng/mL; all prescribed calcium · source_derived_draft · unverified_draft

### vd-gordon-pth PTH suppression did not differ significantly among the three vitamin D regimens given with calcium. Condition category: biomarker_context nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The hormone response was not detectably different between these treatment groups. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Six-week randomized comparison in 40 infants/toddlers with 25(OH)D<20 ng/mL; all prescribed calcium limitations: Small pediatric trial; D and calcium effects cannot be separated; biochemical outcomes do not establish long-term comparative safety. exposure: D2 2000 IU/day, D2 50, 000 IU/week or D3 2000 IU/day for 6 weeks; all also 50 mg/kg/day elemental calcium. cross_nutrient: true [gordon2008] Treatment of hypovitaminosis D in infants and toddlers. (2008). https://pubmed.ncbi.nlm.nih.gov/18413426/ DOI: 10.1210/jc.2007-2790

cross_nutrient

false

experimental_model

Two randomized single-dose experiments; 100 volunteers, 97 analyzed

exposure

Study 2: D2 50, 000 IU preload; four days later D3 50, 000 IU or placebo.

limitations

No direct enzyme-flux assay. Reciprocal fraction changes are not proof that D2 is toxic or that net total vitamin D falls.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The reverse effect also occurred after D3, and its between-group difference was shorter-lived.

primary_references

[hammami2019] Vitamin-D2 treatment-associated decrease in 25(OH)D3 level is a reciprocal phenomenon: a randomized controlled trial. (2019). https://pubmed.ncbi.nlm.nih.gov/30658603/ DOI: 10.1186/s12902-019-0337-8

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1418–1429

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Two randomized single-dose experiments; 100 volunteers, 97 analyzed · source_derived_draft · unverified_draft

### vd-hammami-d3-decreases-d2 At day 28, D3 produced a 9.8 nmol/L greater decline in 25(OH)D2 than placebo (95% CI5.2–14.4); by day 56 the 1.7 nmol/L difference was not significant (CI−7.6–11.1). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The reverse effect also occurred after D3, and its between-group difference was shorter-lived. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Two randomized single-dose experiments; 100 volunteers, 97 analyzed limitations: No direct enzyme-flux assay. Reciprocal fraction changes are not proof that D2 is toxic or that net total vitamin D falls. exposure: Study 2: D2 50, 000 IU preload; four days later D3 50, 000 IU or placebo. cross_nutrient: false [hammami2019] Vitamin-D2 treatment-associated decrease in 25(OH)D3 level is a reciprocal phenomenon: a randomized controlled trial. (2019). https://pubmed.ncbi.nlm.nih.gov/30658603/ DOI: 10.1186/s12902-019-0337-8

cross_nutrient

false

experimental_model

Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks

exposure

D2 or D3 50, 000 IU orally each week for 12 weeks.

limitations

This weekly regimen and marker response do not establish a universal conversion factor or superiority for every clinical endpoint.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

D3 produced the larger accumulated blood-marker response during weekly dosing.

primary_references

[heaney2011] Vitamin D(3) is more potent than vitamin D(2) in humans. (2011). https://pubmed.ncbi.nlm.nih.gov/21177785/ DOI: 10.1210/jc.2010-2230

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1301–1312

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks · source_derived_draft · unverified_draft

### vd-heaney-auc Incremental 12-week 25(OH)D AUC averaged 2136 ng·day/mL for D3 versus 1366 for D2 (P<0.001). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: D3 produced the larger accumulated blood-marker response during weekly dosing. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks limitations: This weekly regimen and marker response do not establish a universal conversion factor or superiority for every clinical endpoint. exposure: D2 or D3 50, 000 IU orally each week for 12 weeks. cross_nutrient: false [heaney2011] Vitamin D(3) is more potent than vitamin D(2) in humans. (2011). https://pubmed.ncbi.nlm.nih.gov/21177785/ DOI: 10.1210/jc.2010-2230

cross_nutrient

false

experimental_model

Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks

exposure

D2 or D3 50, 000 IU orally each week for 12 weeks.

limitations

This weekly regimen and marker response do not establish a universal conversion factor or superiority for every clinical endpoint.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The later steady blood-level rise also differed between the forms.

primary_references

[heaney2011] Vitamin D(3) is more potent than vitamin D(2) in humans. (2011). https://pubmed.ncbi.nlm.nih.gov/21177785/ DOI: 10.1210/jc.2010-2230

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1314–1325

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks · source_derived_draft · unverified_draft

### vd-heaney-steady-state Mean steady-state total 25(OH)D increments were 45 ng/mL with D3 and 24 ng/mL with D2 (P<0.001). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The later steady blood-level rise also differed between the forms. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Single-blind randomized D2/D3 comparison in 33 adults; weekly dosing for 12 weeks limitations: This weekly regimen and marker response do not establish a universal conversion factor or superiority for every clinical endpoint. exposure: D2 or D3 50, 000 IU orally each week for 12 weeks. cross_nutrient: false [heaney2011] Vitamin D(3) is more potent than vitamin D(2) in humans. (2011). https://pubmed.ncbi.nlm.nih.gov/21177785/ DOI: 10.1210/jc.2010-2230

cross_nutrient

false

experimental_model

Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks

exposure

Daily D2 1000 IU, D3 1000 IU, mixed 500+500 IU or placebo; 11 winter weeks.

limitations

Small groups and biochemical endpoints; authors reported comparable responses. Daily regimen differs from single-dose and food-fortification studies.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

A mixture also raised the marker; this was not a test proving synergy.

primary_references

[holick2008] Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. (2008). https://pubmed.ncbi.nlm.nih.gov/18089691/ DOI: 10.1210/jc.2007-2308

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1275–1286

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks · source_derived_draft · unverified_draft

### vd-holick-mixed With the 500-IU D2 plus 500-IU D3 daily combination, mean total 25(OH)D rose from 20.2 to 28.4 ng/mL. Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: A mixture also raised the marker; this was not a test proving synergy. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Double-blind placebo-controlled daily D2/D3/mixed trial; 68 adults represented in Fig.1; 11 weeks limitations: Small groups and biochemical endpoints; authors reported comparable responses. Daily regimen differs from single-dose and food-fortification studies. exposure: Daily D2 1000 IU, D3 1000 IU, mixed 500+500 IU or placebo; 11 winter weeks. cross_nutrient: false [holick2008] Vitamin D2 is as effective as vitamin D3 in maintaining circulating concentrations of 25-hydroxyvitamin D. (2008). https://pubmed.ncbi.nlm.nih.gov/18089691/ DOI: 10.1210/jc.2007-2308

cross_nutrient

false

experimental_model

Randomized double-blind five-group food-fortification trial; 335 South Asian and white European women

exposure

Daily 15 micrograms D2 or D3 in juice or biscuits versus placebo; 12 winter weeks.

limitations

Women aged 20–64 in the UK; food vehicles and dose differ from other trials. Marker superiority is not proof of better disease outcomes.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

With matched fortified biscuits, D3 produced a larger marker increase.

primary_references

[tripkovic2017] Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial. (2017). https://pubmed.ncbi.nlm.nih.gov/28679555/ DOI: 10.3945/ajcn.116.138693

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1353–1364

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized double-blind five-group food-fortification trial; 335 South Asian and white European women · source_derived_draft · unverified_draft

### vd-tripkovic-biscuit The D3-biscuit group had a 15.3 nmol/L greater incremental total 25(OH)D change than D2-biscuit (95% CI7.4–23.3; P<0.0003). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: With matched fortified biscuits, D3 produced a larger marker increase. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Randomized double-blind five-group food-fortification trial; 335 South Asian and white European women limitations: Women aged 20–64 in the UK; food vehicles and dose differ from other trials. Marker superiority is not proof of better disease outcomes. exposure: Daily 15 micrograms D2 or D3 in juice or biscuits versus placebo; 12 winter weeks. cross_nutrient: false [tripkovic2017] Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial. (2017). https://pubmed.ncbi.nlm.nih.gov/28679555/ DOI: 10.3945/ajcn.116.138693

cross_nutrient

false

experimental_model

Randomized double-blind five-group food-fortification trial; 335 South Asian and white European women

exposure

Daily 15 micrograms D2 or D3 in juice or biscuits versus placebo; 12 winter weeks.

limitations

Women aged 20–64 in the UK; food vehicles and dose differ from other trials. Marker superiority is not proof of better disease outcomes.

nutrient_topic

Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. · Vitamin D2 and D3

organism

Homo sapiens

plain_language

The matched-juice comparison also favored D3 for this blood marker.

primary_references

[tripkovic2017] Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial. (2017). https://pubmed.ncbi.nlm.nih.gov/28679555/ DOI: 10.3945/ajcn.116.138693

tissue_or_cell_type

Human circulating measurements

Vitamin D2 and D3: mechanisms, deficiency and nutrient interactions (2026-09-17) · lines 1366–1377

AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Randomized double-blind five-group food-fortification trial; 335 South Asian and white European women · source_derived_draft · unverified_draft

### vd-tripkovic-juice The D3-juice group had a 16.9 nmol/L greater incremental total 25(OH)D change than D2-juice (95% CI9.0–24.8; P<0.0001). Condition category: normal nutrient_topic: Vitamin D2 and D3 research collection; topical membership is not evidence of a direct dietary effect. plain_language: The matched-juice comparison also favored D3 for this blood marker. organism: Homo sapiens tissue_or_cell_type: Human circulating measurements experimental_model: Randomized double-blind five-group food-fortification trial; 335 South Asian and white European women limitations: Women aged 20–64 in the UK; food vehicles and dose differ from other trials. Marker superiority is not proof of better disease outcomes. exposure: Daily 15 micrograms D2 or D3 in juice or biscuits versus placebo; 12 winter weeks. cross_nutrient: false [tripkovic2017] Daily supplementation with 15 μg vitamin D2 compared with vitamin D3 to increase wintertime 25-hydroxyvitamin D status in healthy South Asian and white European women: a 12-wk randomized, placebo-controlled food-fortification trial. (2017). https://pubmed.ncbi.nlm.nih.gov/28679555/ DOI: 10.3945/ajcn.116.138693