What disease is caused by vitamin D deficiency?

Vitamin D helps the body absorb calcium and supports normal bone and muscle function. When levels remain low, bones may become less mineralised. In adults, this can lead to osteomalacia, which may cause diffuse bone discomfort, muscle weakness or difficulty climbing stairs and rising from a chair. In children, deficiency can interfere with growing bones and cause rickets.

Possible symptoms include fatigue, generalised weakness, joint pain or low mood, but these symptoms are not specific to vitamin D deficiency. Frequent infections may have many explanations as well. Reduced sunlight exposure, limited dietary intake, problems absorbing nutrients and some medical conditions can all contribute. Obesity can also be associated with lower measured vitamin D because the vitamin is distributed differently in the body.

Speak with a clinician if symptoms continue or if you have factors that may reduce vitamin D. Assessment may include your symptoms, diet, sunlight exposure, medicines and medical history, together with a blood test. The clinician may also consider calcium and bone health when deciding what to check.

Treatment is usually a clinician-recommended vitamin D supplement, with the dose and schedule matched to the severity and cause. Food sources and safe, sensible outdoor exposure may support vitamin D, but sunlight should not be used to the point of skin damage. Taking more supplement than advised can cause harm, so check before combining products.

Arrange an appointment for persistent bone or joint pain, unexplained muscle weakness, repeated falls, or fatigue that is limiting normal activities. Seek prompt care after a minor injury causes marked pain or loss of function, especially if a fracture is possible. Urgent help is appropriate for severe weakness, confusion, chest symptoms or difficulty breathing, because these signs can indicate another problem requiring rapid assessment.

Ask whether your symptoms fit vitamin D deficiency or another condition, which blood tests are needed, and whether your bones or calcium level need checking. Discuss the recommended supplement, how it should be taken, when results should be reviewed, and whether any medicines or digestive problems could affect absorption.