All Glossary Terms
Nutrition

Vitamin D

A fat-soluble vitamin essential for bone health, immunity, and hormone function.

Updated

Vitamin D is synthesized in skin from sunlight and found in few foods (fatty fish, fortified products). It is crucial for calcium absorption, bone health, immune function, and may affect muscle function and testosterone. Deficiency is common, especially in northern latitudes. Many people benefit from supplementation.

Examples

  • Made from sunlight on skin
  • Few food sources (fatty fish)
  • Common deficiency, often supplemented

Common questions

What is Vitamin D?

A fat-soluble vitamin essential for bone health, immunity, and hormone function. Vitamin D is synthesized in skin from sunlight and found in few foods (fatty fish, fortified products).

What are examples of Vitamin D?

Made from sunlight on skin; Few food sources (fatty fish); Common deficiency, often supplemented.

Put it into practice

Macro Tracking Masterclass · £12

Set your calories and macros, track them accurately, and fix a stall: a 3-page guide plus an Excel calculator

Explore More Terms

Browse our complete fitness glossary with 266 terms.

View All Terms