What causes vitamin D deficiency?

The skin makes vitamin D after exposure to sunlight, but indoor living, covering most of the skin, darker skin, and avoiding strong sun can reduce production. Food provides some vitamin D, yet a diet with few fortified foods or oily fish may not provide enough. Digestive disorders and some operations can reduce absorption.

Vitamin D is stored in body fat, so obesity can be associated with lower available vitamin D. Liver or kidney problems and some medicines may also affect processing. Low vitamin D may have no clear symptoms; when symptoms occur, they can include muscle aches, weakness, or bone discomfort. A blood test is the usual way to check the level.

Discuss testing with a clinician if you have persistent muscle or bone symptoms, a digestive condition, limited sun exposure, or another risk factor. Treatment may involve a prescribed supplement, a food-based plan, or both. The amount and duration should match your blood result and health history. Avoid taking high-dose supplements without guidance, because excess vitamin D can disturb calcium balance.

Book an appointment for ongoing bone pain, muscle weakness, repeated falls, or difficulty climbing stairs. Seek urgent care for severe weakness, confusion, persistent vomiting, or symptoms of a serious illness. These problems can have causes other than vitamin D deficiency and need timely assessment.

Ask whether a blood test is appropriate, whether obesity or a digestive problem could affect your level, and which supplement is suitable for you. Clarify when to repeat testing and whether calcium, kidney, liver, or bone checks are needed alongside vitamin D.