Vitamin

Vitamin D3

Vitamin studied for bone health, immune function, mood support. How it works, the dose and timing studied, what it interacts with, and the research behind the grade.

Grade A evidence strong: trials and meta-analyses agree Also known as Cholecalciferol
All compounds
Best for Bone health, Immune function, Mood support, Testosterone support
Typical dose 1,000–4,000 IU daily; target serum 25(OH)D of 40–60 ng/mL
Timing With a fat-containing meal; morning preferred to avoid potential sleep disruption
Category Vitamin
How it works

What it is and the mechanism

Binds the vitamin D receptor (VDR), a nuclear receptor present in virtually every tissue, regulating expression of over 1,000 genes. Deficiency is associated with impaired immune response, poor mood, and reduced testosterone in men.

Dose and timing

When and how much to take

The dose below reflects the range used in published research. Match the form alongside the milligrams. Set your own wake and bed times to map the timing onto your day.

Timing visualizer

When to take Vitamin D3

Dose: 1,000–4,000 IU daily; target serum 25(OH)D of 40–60 ng/mL. Set your own wake and bed times to map the guidance onto your day.

12a6a12p6pDAY1 dose
8 amMorning. Take early in the day.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease.

Before you stack it

Interactions and cautions

Read these before combining this with other supplements or medication. The risk is rarely the headline, it is the interaction you did not check.

Interactions
  • Vitamin K2, co-supplementation supports calcium routing to bone rather than arteries
Cautions
  • Toxicity above 10,000 IU/day sustained, test serum levels before megadosing
  • Hypercalcemia with very high doses
Stacking

What pairs well, and what to keep apart

Derived from shared topics, complementary categories, and the interaction list. Introduce one compound at a time so you can tell what works.

Explore more

Compounds in the same topics

Often considered alongside this one. Each carries its own evidence grade.