Vitamins & minerals
Vitamin D
Names you may see: cholecalciferol ergocalciferol D3 D2
The quick take
Vitamin D helps the body absorb calcium and supports bone health, muscle function and immune function.
A closer look
What forms will I see on a label?
D2 (ergocalciferol) and D3 (cholecalciferol) are common forms. Labels may use micrograms or international units.
Why people use it
People choose vitamin D to meet their needs and support bones, muscles and immune function, particularly when intake or vitamin D status is low.
These are common goals and marketing uses. The evidence section below explains what research supports.
What does the evidence tell us?
Correcting low vitamin D is different from assuming high doses improve every health outcome. Needs depend on intake, sun exposure and individual circumstances.
What should I know before using it?
Excess vitamin D can raise blood calcium and cause harm. Account for all vitamin D-containing products and follow professional advice for high-dose use.
Sources & further reading
NIH Office of Dietary Supplements ↗
Content reviewed: September 30, 2026
General educational information. Follow the product label and seek individual advice when needed.