# Vitamin D3

*Also known as: Cholecalciferol, Vitamin D*

Cholecalciferol; fat-soluble vitamin important for bone health, immunity, and hormonal balance.

## Overview

Vitamin D3 (cholecalciferol) is a fat-soluble vitamin that the body converts to the active hormone calcitriol (1,25-dihydroxyvitamin D), which regulates calcium absorption, bone mineralization, and immune function. The major circulating form, 25-hydroxyvitamin D (calcifediol), has a half-life of roughly 15 days, while the active calcitriol form clears faster at about 15 hours. The parent compound is stored in adipose tissue with an estimated half-life of up to 50 days, which is why it is excluded from the plotter. Injectable cholecalciferol exists but the standard clinical route is oral supplementation, with injection reserved for documented malabsorption or severe deficiency. Prescription dosing is guided by serum 25-hydroxyvitamin D levels, and toxicity (hypercalcemia) is real at excessive doses. Per the NIH Office of Dietary Supplements, evidence for benefit beyond bone health in replete individuals is mixed. We list it for catalog completeness, not as a recommendation, and any dosing should be guided by lab values.

## Pharmacokinetics

- **Model tier:** simple
- **Half-life:** 15.0 days (360 hours)
- **Bioavailability:** 0%

## Dosing

- **Default dose:** 0.025 mg
- **Typical range:** 0.025–0.05 mg
- **Units:** ng/mL

## Source

- **Label:** NIH ODS Vitamin D Fact Sheet + StatPearls (Cholecalciferol)
- **URL:** https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
- **Notes:** 25(OH)D calcifediol half-life ~15 days; calcitriol ~15 hours. Parent D3 tissue storage ~50 days.

**Tags:** immune, hormone-support

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**Canonical URL:** https://anabolicdex.com/compounds/vitamin-d3
**Plot:** https://anabolicdex.com/plot?compound=vitamin-d3