NutriStack
InfoSynergy
MCT Oil
MCT Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin D2.
Recommendation: Take Vitamin D2 with MCT Oil or another fat-containing meal to improve absorption.
Vitamin D2
Vitamin ·Moderate evidence ·Reviewed May 2026
Plant-derived form of vitamin D, less potent than D3 but suitable for vegans.
The bottom line
Evidence rating moderate. Most-documented uses: bone health, immune support, vegan-friendly d source. 16 sources indexed (2006–2024), with 11 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
Converted to 25-hydroxyvitamin D2 in the liver. Less efficiently raises serum 25(OH)D levels compared to D3.1,8
Class
Fat-Soluble Vitamin
Found in food
UV-exposed mushrooms, Fortified foods, Fortified plant milks
Low-status signs
Same as D3 deficiency
Absorption
Fat-soluble; take with food
Dosing
Dosing & protocol.
Common range
1,000-2,000 IU daily
Recommended form
Ergocalciferol from UV-irradiated mushrooms
Forms
Forms & what to buy.
Ranked by evidence and value.
Vitamin D3 (Cholecalciferol) Recommended
Preferred maintenance form for most people. Usually raises and sustains 25-OH vitamin D better than D2.
Vitamin D2 (Ergocalciferol)
Plant-derived but less effective at maintaining serum levels than D3. Often used in high-dose prescription products.
Calcifediol
25-hydroxyvitamin D3 that raises serum levels rapidly. Pre-converted form can raise 25-OH vitamin D faster than D3.
Cost
What it actually costs.
Real-world pricing across three quality tiers. Assumes Ergocalciferol.
BudgetBest value
$1.50 /mo
$0.05 per dose
Mid
$3.60 /mo
$0.12 per dose
Premium
$7.50 /mo
$0.25 per dose
Assumes 1,000-2,000 IU/day. Vendor basis: iHerb, Vitacost, Amazon marketplace, and specialty vegan D2 products; D2 is less commonly stocked than D3. Updated 2026-05-28.
From food
The same dose, as food.
How much you'd eat to match a supplemental dose.
1,000-2,000 IU vitamin D2
About 1/2-1 cup UV-exposed mushrooms, fortified plant milk, fortified cereal, fortified orange juice, or other D2-fortified foods can contribute vitamin D2.
Vitamin D2 content depends heavily on UV exposure and fortification level.
Goals
Goal-based dosing.
Bone Health
Dose: 1,000-2,000 IU daily12
Timing: With a fat-containing meal
Clinical dose evidence: PMID 34684328.
Lab work
Markers to track.
What to test, the optimal window inside the conventional range, and how long a response takes.
25-Hydroxyvitamin D 25(OH)D
Effective vitamin D2 supplementation should raise serum 25(OH)D, though the response can be less durable than D3 and targets should be individualized.1,2
Optimal
30–50 ng/mL
Conventional
30–100 ng/mL
Responds in
8-12 weeks after starting or changing dose.
30optimal100
Use the same 25(OH)D assay used for D3 follow-up so serial results are comparable.
CalciumParathyroid Hormone
Why people use it
Symptoms it's matched to.
Where this appears in the symptom-to-supplement map, ranked by relevance.
Alopecia areata (autoimmune patchy hair loss) adjunctive support
55% relevance
Like D3, vitamin D2 raises 25-OH vitamin D and can help correct the low status linked to alopecia areata.
AppearanceInsufficient evidenceVitamin D2 used only if a vegan or specific clinical reason precludes D3
D3 is generally preferred for raising levels; use D2 only when needed. Adjunctive to medical care.
Genetics
Who responds differently.
VDRFokI / BsmI / TaqI / ApaI~30% of population
Vitamin D receptor variants are being studied, but they should not be treated as a validated explanation for symptoms or dose needs.
Recommendation: Follow measured 25(OH)D response and clinician guidance; consider D3 if D2 repletion is inadequate.
Safety
Full safety detail.
Interactions
Interaction records.
InfoSynergy
Flaxseed Oil
Flaxseed Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin D2.
Recommendation: Take Vitamin D2 with Flaxseed Oil or another fat-containing meal to improve absorption.
InfoSynergy
Evening Primrose Oil
Evening Primrose Oil provides a fat-containing carrier that can improve absorption of fat-soluble compounds like Vitamin D2.
Recommendation: Take Vitamin D2 with Evening Primrose Oil or another fat-containing meal to improve absorption.
InfoSynergy
Magnesium Glycinate
Magnesium is required for the body to convert Vitamin D2 into its biologically active form. With low magnesium status, supplemental D2 is metabolized less efficiently, so correcting magnesium can improve the response to vitamin D supplementation.
Recommendation: Ensure adequate magnesium status (roughly 200 to 400 mg elemental magnesium daily from diet plus supplement) when supplementing Vitamin D2, especially at higher D2 doses. No timing separation is needed; both can be taken with a meal. If vitamin D levels respond poorly to supplementation, check and correct magnesium first.
ModerateTiming Sensitive
Calcium
Vitamin D2 increases how much dietary and supplemental calcium the gut absorbs, which is beneficial for bone health at sensible doses but can become problematic when both are taken in large amounts together, raising the risk of hypercalcemia and kidney stones.
Recommendation: Pairing modest doses is appropriate for bone health: keep total supplemental calcium around 500 to 1000 mg/day (split into 500 mg doses with food for absorption) alongside standard D2 dosing. Avoid combining high-dose D2 with high-dose calcium without monitoring. Anyone on large D2 doses plus calcium, or with a history of kidney stones, hyperparathyroidism, or sarcoidosis, should have serum and urinary calcium checked periodically. Watch for nausea, excessive thirst, frequent urination, or confusion as signs of hypercalcemia.
ModerateCaution
Hydrochlorothiazide
Hydrochlorothiazide reduces urinary calcium excretion, and Vitamin D2 can increase calcium absorption after conversion to active vitamin D metabolites. The concern is hypercalcemia when Vitamin D2 is taken in high doses or combined with high calcium intake. People with kidney disease, hyperparathyroidism, granulomatous disease, or dehydration are at higher risk.
Recommendation: Do not combine hydrochlorothiazide with high-dose Vitamin D2 without a monitoring plan. Ask for serum calcium monitoring after starting or changing Vitamin D2, especially if you also take calcium or have a history of kidney stones.
ModerateCaution
Chlorthalidone
Chlorthalidone reduces urinary calcium excretion, and Vitamin D2 can increase calcium absorption after metabolic activation. High-dose Vitamin D2 can therefore add to chlorthalidone's calcium-retaining effect. The concern is greatest when calcium supplements are also used or when kidney disease, hyperparathyroidism, granulomatous disease, or dehydration is present.
Recommendation: Avoid high-dose Vitamin D2 with chlorthalidone unless your clinician is tracking calcium. If Vitamin D2 is prescribed, ask when to recheck serum calcium and whether your calcium supplement dose should be adjusted.
ModerateSynergy
Prednisone
Long-term prednisone therapy can cause rapid bone loss and increase fracture risk. Vitamin D2 can help maintain vitamin D status and calcium absorption as part of glucocorticoid-induced osteoporosis prevention.
Recommendation: Use vitamin D2 only as part of a complete bone-protection plan that includes calcium intake, vitamin D status monitoring, and fracture-risk assessment. If you are on prednisone for more than a short course, ask whether you need bone density testing or prescription osteoporosis prevention.
ModerateSynergy
Prednisolone
Prednisolone increases fracture risk when used chronically by accelerating bone loss. Vitamin D2 can help maintain vitamin D status, which supports calcium absorption and is part of standard glucocorticoid-induced osteoporosis prevention.
Recommendation: If prednisolone use is prolonged, maintain vitamin D status with diet, sunlight exposure where appropriate, or supplementation such as vitamin D2. Have bone risk assessed rather than assuming vitamin D2 alone is enough protection.
ModerateSynergy
Methylprednisolone
Chronic methylprednisolone exposure can reduce bone density and raise fracture risk. Vitamin D2 can help maintain vitamin D status and calcium absorption, which are core parts of glucocorticoid-induced osteoporosis prevention.
Recommendation: If methylprednisolone is used beyond a short course, maintain vitamin D status and ask whether bone density testing or prescription osteoporosis prevention is appropriate. Vitamin D2 should complement calcium intake and risk-based treatment decisions, not replace them.
ModerateSynergy
Dexamethasone
Dexamethasone is a potent systemic glucocorticoid, and prolonged use can accelerate bone loss. Vitamin D2 can help maintain vitamin D status and calcium absorption as part of prevention for glucocorticoid-induced osteoporosis.
Recommendation: For repeated or long dexamethasone courses, maintain adequate vitamin D status and review fracture risk with your clinician. Vitamin D2 is supportive; it does not replace bone density testing or osteoporosis medication when those are indicated.
Sources
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Meta-analyses & systematic reviews
3- 1Comparison of the Effect of Daily Vitamin D2 and Vitamin D3 Supplementation on Serum 25-Hydroxyvitamin D Concentration (Total 25(OH)D, 25(OH)D2, and 25(OH)D3) and Importance of Body Mass Index: A Systematic Review and Meta-AnalysisNeeds reviewPMIDItkonen ST et al. · Adv Nutr · 2023
Average daily dose was the single significant predictor of effect size difference between D2 and D3, with BMI potentially moderating absorption.
- 2Relative Efficacy of Vitamin D2 and Vitamin D3 in Improving Vitamin D Status: Systematic Review and Meta-AnalysisNeeds reviewPMIDBalachandar R et al. · Am J Clin Nutr · 2021
Meta-analysis of 1,277 participants from 24 studies found cholecalciferol (D3) raised total 25(OH)D 15.69 nmol/L higher than ergocalciferol (D2), with smaller differences at lower doses.
- 3Model-based meta-analysis for comparing Vitamin D2 and D3 parent-metabolite pharmacokineticsNeeds reviewPMIDOcampo-Pelland AS, Gastonguay MR, Riggs MM · Journal of pharmacokinetics and pharmacodynamics · 2017
Ocampo-Pelland AS, Gastonguay MR, Riggs MM. Model-based meta-analysis for comparing Vitamin D2 and D3 parent-metabolite pharmacokinetics. Journal of pharmacokinetics and pharmacodynamics. 2017
Randomized controlled trials
5- 4Vitamins D2 and D3 Have Overlapping But Different Effects on the Human Immune System Revealed Through Analysis of the Blood TranscriptomeNeeds reviewPMIDDurrant LR et al. · Front Immunol · 2022
D2 and D3 share structural similarity but functional equivalence in vitamin D-dependent effects on human physiology has not been well defined; transcriptomic analysis reveals different immune modulation.
- 5Ergocalciferol in New-onset Type 1 Diabetes: A Randomized Controlled TrialNeeds reviewPMIDNwosu BU, Parajuli S, Jasmin G et al. · Journal of the Endocrine Society · 2022
Nwosu BU, Parajuli S, Jasmin G et al.. Ergocalciferol in New-onset Type 1 Diabetes: A Randomized Controlled Trial. Journal of the Endocrine Society. 2022
- 6Ergocalciferol Supplementation in Hemodialysis Patients With Vitamin D Deficiency: A Randomized Clinical TrialNeeds reviewPMIDMiskulin DC, Majchrzak K, Tighiouart H et al. · Journal of the American Society of Nephrology : JASN · 2016
Miskulin DC, Majchrzak K, Tighiouart H et al.. Ergocalciferol Supplementation in Hemodialysis Patients With Vitamin D Deficiency: A Randomized Clinical Trial. Journal of the American Society of Nephrology : JASN. 2016
- 7Ergocalciferol supplementation in children with CKD delays the onset of secondary hyperparathyroidism: a randomized trialNeeds reviewPMIDShroff R, Wan M, Gullett A et al. · Clinical journal of the American Society of Nephrology : CJASN · 2012
Shroff R, Wan M, Gullett A et al.. Ergocalciferol supplementation in children with CKD delays the onset of secondary hyperparathyroidism: a randomized trial. Clinical journal of the American Society of Nephrology : CJASN. 2012
- 8Vitamin D2 is much less effective than vitamin D3 in humansSource linkedPMIDHeaney RP, Recker RR, Grote J et al. · J Clin Endocrinol Metab · 2011
Reviews & position papers
7- 9Clinical Efficacy and Mechanism of Vitamin D2 in Treating Hashimoto's ThyroiditisNeeds reviewPMIDGan L, Li Y · Journal of inflammation research · 2024
Gan L, Li Y. Clinical Efficacy and Mechanism of Vitamin D2 in Treating Hashimoto's Thyroiditis. Journal of inflammation research. 2024
- 10Efficacy of plain cholecalciferol versus ergocalciferol in raising serum vitamin D level in Thai female healthcare workersNeeds reviewPMIDAmphansap T, Therdyothin A, Stitkitti N et al. · Osteoporosis and sarcopenia · 2022
Amphansap T, Therdyothin A, Stitkitti N et al.. Efficacy of plain cholecalciferol versus ergocalciferol in raising serum vitamin D level in Thai female healthcare workers. Osteoporosis and sarcopenia. 2022
- 11Immunologic Effects of Vitamin D on Human Health and DiseaseNeeds reviewPMIDCharoenngam N et al. · Nutrients · 2020
Active vitamin D generates immunologic activities on innate and adaptive immune systems; deficiency associated with increased autoimmunity and susceptibility to infection.
- 12Treatment Effect of Ergocalciferol on Bone Metabolism Indexes and Parathyroid Hormone in Hemodialysis PatientsNeeds reviewPMIDBashardoust B, Zakeri A, Fouladi N et al. · Iranian journal of kidney diseases · 2018
Bashardoust B, Zakeri A, Fouladi N et al.. Treatment Effect of Ergocalciferol on Bone Metabolism Indexes and Parathyroid Hormone in Hemodialysis Patients. Iranian journal of kidney diseases. 2018
- 13Comparative efficacy and safety of different doses of ergocalciferol supplementation in patients with metabolic syndromeNeeds reviewPMIDSansanayudh N, Wongwiwatthananukit S, Phetkrajaysang N et al. · International journal of clinical pharmacy · 2014
Sansanayudh N, Wongwiwatthananukit S, Phetkrajaysang N et al.. Comparative efficacy and safety of different doses of ergocalciferol supplementation in patients with metabolic syndrome. International journal of clinical pharmacy. 2014
- 14The lack of vitamin D toxicity with megadose of daily ergocalciferol (D2) therapy: a case report and literature reviewNeeds reviewPMIDStephenson DW, Peiris AN · Southern medical journal · 2009
Stephenson DW, Peiris AN. The lack of vitamin D toxicity with megadose of daily ergocalciferol (D2) therapy: a case report and literature review. Southern medical journal. 2009
- 15The case against ergocalciferol (vitamin D2) as a vitamin supplementNeeds reviewPMIDHoughton LA et al. · Am J Clin Nutr · 2006
Vitamin D2 has shorter plasma half-life, lower affinity for vitamin D binding protein, hepatic hydroxylase and VDR; should not be regarded as equivalent to vitamin D3.
Keep exploring
Deep dives & adjacent profiles.
This page is educational. Do not start, stop, or change a supplement or medication based on it without checking with a qualified healthcare professional.
Use this with your stack
Vitamin D2 in NutriStack.
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