Calcifediol (25-hydroxyvitamin D3)

Vitamin D

Used to rapidly correct vitamin D deficiency; monitor serum calcium and 25(OH)D levels during therapy.

Part of Vitamin D Vitamins
Compare all forms

Typical dose

Dosage is highly individualized based on baselin...

Oral Oral safety: very low

About this supplement

Calcifediol, also known as 25-hydroxyvitamin D3, is the major circulating metabolite of vitamin D3 (cholecalciferol) and the primary clinical indicator of vitamin D status in the body. It is produced in the liver via hydroxylation of vitamin D3 by the enzyme vitamin D 25-hydroxylase (CYP2R1, CYP27A1). Unlike the parent vitamin D3, calcifediol is not biologically active itself but serves as the direct precursor to the active hormonal form, calcitriol (1,25-dihydroxyvitamin D3), which is generated in the kidneys. It has a longer half-life (approximately 2-3 weeks) compared to vitamin D3, making it a useful therapeutic agent for rapidly correcting vitamin D deficiency, especially in individuals with impaired hepatic hydroxylation or malabsorption syndromes.

How much to take

Typical amount
Dosage is highly individualized based on baseline serum 25(OH)D levels and clinical condition. Typical medical doses range from 20-200 mcg (800-8000 IU vitamin D equivalent) daily or weekly. Available as oral capsules or liquid formulations.
Suggested range
20-100 mcg daily (for deficiency correction under medical supervision)

Potential benefits

Benefits linked to this supplement form:

Testosterone Support

Research strength: Moderate

 Bone Health

Research strength: Very strong

 Immune Support

Research strength: Strong

 Mood Regulation

Research strength: Moderate

 Muscle Function

Research strength: Strong

 Immune System Support

Research strength: Strong

 Bone Health & Mineralization

Research strength: Very strong

 Cell Growth Regulation

Research strength: Moderate

 Rapid Correction of Vitamin D Deficiency

Research strength: Very strong

 Support for Bone Health

Research strength: Very strong

 Management in Chronic Kidney Disease (CKD)

Research strength: Strong

Things to watch for

Possible side effects linked to this form:

Hypercalcemia

How serious: Severe

 Kidney Stones

How serious: Moderate

 Gastrointestinal Discomfort

How serious: low

 Nausea & Constipation

How serious: low

 Hypercalciuria

How serious: medium

Health goals

Needs and goals this form may help with:

Other forms of Vitamin D

Compare absorption and active amounts with sibling forms:

Cholecalciferol (D3)

Essential for calcium absorption and bone health. Often supplemented in regions...
Vitamin D (cholecalciferol)
Vitamin D (ergocalciferol)
Vitamin D (mixed)
Vitamin D (unspecified)
Vitamin D2
Vitamin D3
Vitamin D3 in oil (softgel/liquid)

Take with a meal containing fat for optimal absorption. Store in a cool, dark pl...
Vitamin D3 powder (often on carrier)

Essential for bone health and calcium absorption. Often supplemented in regions...
Compare all forms in the table
Technical details â–¼

Chemical ID (CAS)

19356-17-3

Formula

C27H44O2

Physical properties

White to off-white crystalline powder. Practically insoluble in water, soluble in organic solvents such as ethanol, chloroform, and methanol. Sensitive to light and oxidation.

How it’s made

Primarily produced synthetically via chemical or enzymatic hydroxylation of cholesterol-derived 7-dehydrocholesterol or vitamin D3. Industrial synthesis involves photochemical conversion, extraction, and purification steps. Also available as a purified metabolite from natural sources (e.g., lanolin-derived vitamin D3).