IGCSE Biology glossary
Vitamin D
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A fat-soluble vitamin needed for the absorption of calcium and phosphorus from the gut, essential for strong bones and teeth. Sources include oily fish, eggs and sunlight exposure on skin. Deficiency causes rickets in children.
What to include in an exam answer
Know the link: vitamin D deficiency leads to rickets (soft, deformed bones) because calcium cannot be properly absorbed. Vitamin D is made in the skin when exposed to sunlight.
Example in context
Explain why a child with vitamin D deficiency may develop rickets (2 marks): Without vitamin D, calcium is not absorbed properly from the intestine. Bones do not harden sufficiently and become soft and deformed.
Related syllabus topic
Human nutrition