Cholecalciferol is slightly more effective than ergocalciferol in increasing serum 25(OH)D levels in older adults, with both showing significant between-individual response.

Evaluation of ergocalciferol or cholecalciferol dosing, 1,600 IU daily or 50,000 IU monthly in older adults.

Cholecalciferol is more effective than ergocalciferol in improving vitamin D status and regulating PTH levels, regardless of participant demographics, dosage, and supplementation vehicle.

Relative Efficacy of Vitamin D2 and Vitamin D3 in Improving Vitamin D Status: Systematic Review and Meta-Analysis

All four schedules of vitamin D replacement effectively achieved and maintained 25(OH)D levels above 30 ng/mL, with 50,000 IU D2 twice weekly providing the most rapid and highest mean levels.

A PROSPECTIVE STUDY OF COMMONLY UTILIZED REGIMENS OF VITAMIN D REPLACEMENT AND MAINTENANCE THERAPY IN ADULTS.

A single vitamin D3 dose of 300,000 IU is most effective in improving vitamin D status and suppressing parathyroid hormone concentrations for up to 3 months.

Large, single-dose, oral vitamin D supplementation in adult populations: a systematic review.

The EFSA Panel recommends a tolerable upper intake level of 100 g vitamin D equivalents/day for adults, 11-17 years, and 50 g for children aged 1-10 years, based on persistent hypercalciuria as a critical endpoint.

Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate

Vitamin D3 increases total 25(OH)D concentration more than vitamin D2, while vitamin D2 supplementation leads to a decrease in 25(OH)D3, explaining the different effect on total 25(OH)D.

Bioavailability of vitamin D(2) and D(3) in healthy volunteers, a randomized placebo-controlled trial.

Vitamin D2 supplements show higher 25(OH)D levels than D3 supplements, with a higher dose and sex-dependent effect on 25(OH)D levels.

Differential effects of vitamin D2 and D3 supplements on 25-hydroxyvitamin D level are dose, sex, and time dependent: a randomized controlled trial

Cholecalciferol is nearly twice as potent as ergocalciferol in increasing serum 25(OH)D levels and modulating serum PTH in elderly female patients with vitamin D deficiency.

Short and long-term variations in serum calciotropic hormones after a single very large dose of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3) in the elderly.

The 10-day oral D3 regimen rapidly and effectively normalized 25(OH)D levels, potentially resulting in higher patient compliance.

Effects of a 10-day course of a high dose calciferol versus a single mega dose of ergocalciferol in correcting vitamin D deficiency

High-dose vitamin D3 supplementation is sufficient for obese infertile men with low vitamin D status to achieve adequate serum 25OHD levels.

High-dose cholecalciferol supplementation to obese infertile men is sufficient to reach adequate vitamin D status

Both low-dose ergocalciferol and cholecalciferol in fortified malted milk drinks effectively raise serum 25-hydroxyvitamin D concentrations in healthy men and women with negligible UV-B exposure.

Fortified malted milk drinks containing low-dose ergocalciferol and cholecalciferol do not differ in their capacity to raise serum 25-hydroxyvitamin D concentrations in healthy men and women not exposed to UV-B.

Weekly high-dose vitamin D3 supplementation significantly increases serum cholecalciferol levels in pregnant women, but the clinically significant minimum threshold remains to be established.

Effect of weekly high-dose vitamin D3 supplementation on serum cholecalciferol concentrations in pregnant women

Vitamin D3 supplementation significantly increases serum levels of 25OHD, IL-6, IL-10, IL-1, and leptin in adults with vitamin D deficiency, but may have a potential negative effect during cytokine storms.

The Effect of Weekly 50,000 IU Vitamin D3 Supplements on the Serum Levels of Selected Cytokines Involved in Cytokine Storm: A Randomized Clinical Trial in Adults with Vitamin D Deficiency

Daily intake of either ergocalciferol or cholecalciferol is acceptable for infants 4 months, with no significant difference in 25(OH)D concentrations.

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 Months1234

Vitamin D supplementation is associated with a reduced risk of suicide attempts and self-harm in Veterans, particularly those with low blood serum levels and Black veterans.

The association between vitamin D serum levels, supplementation, and suicide attempts and intentional self-harm

A single oral megadose of cholecalciferol is more effective than ergocalciferol in treating vitamin D deficiency in patients with alcoholic liver cirrhosis.

The effect of a single oral megadose of vitamin D provided as either ergocalciferol (D2) or cholecalciferol (D3) in alcoholic liver cirrhosis

3-epi-25(OH)D3 is a significant metabolite of 25(OH)D in three patients, indicating it is not a trivial metabolite for all patients.

Case report: Three patients with substantial serum levels of 3-epi-25(OH)D including one with 3-epi-25(OH)D2 while on high-dose ergocalciferol.

Vitamin D3 is the more potent and effective form of vitamin D for supplementation and fortification, while ergocalciferol is less effective and has a shorter shelf life.

The case against ergocalciferol (vitamin D2) as a vitamin supplement.

Species discrimination between ergocalciferol and cholecalciferol is a general phenomenon in mammals, with a rat showing a preference for ergocalciferol metabolites.

Discrimination in the metabolism of orally dosed ergocalciferol and cholecalciferol by the pig, rat and chick.

Megadoses of daily ergocalciferol (150,000 IU) for 28 years in a 56-year-old woman without toxicity have been reported in the literature.

The lack of vitamin D toxicity with megadose of daily ergocalciferol (D2) therapy: a case report and literature review.

How much Vitamin D (D2: Ergocalciferol, and D3: Cholecalciferol) should I take daily?

These studies suggest that cholecalciferol (D3) is generally more effective than ergocalciferol (D2) in increasing serum 25(OH)D levels and regulating PTH, with recommended dosages varying based on individual needs and specific health conditions.