Overview
Vitamin D deficiency means the body has too little vitamin D, a nutrient needed to absorb calcium and keep bones, muscles, and the immune system healthy. The body makes vitamin D from sunlight, and gets some from food, so low levels are common in people with little sun exposure. Mild deficiency often causes no symptoms and is found on a blood test.
Symptoms
- Bone pain or tenderness
- Muscle weakness or aches
- Fatigue
- Frequent illness or infections
- Low mood
- Hair thinning
- Bone softening or fractures in severe, long-standing cases
Causes & risk factors
- Limited sun exposure or living far from the equator
- Darker skin, which makes less vitamin D from sunlight
- Older age
- Diets low in vitamin D
- Conditions that reduce fat absorption in the gut
- Obesity, which can lower available vitamin D
- Some kidney or liver conditions
Treatment & self-care
Care usually starts with a blood test to measure vitamin D levels. Treatment generally involves sensible sun exposure, vitamin-D-rich or fortified foods, and supplements at a dose matched to the deficiency and any underlying cause. A licensed clinician should confirm the diagnosis, set the right dose, and recheck levels, since too much vitamin D can be harmful.
See a doctor urgently if
- You have ongoing bone pain or muscle weakness
- You have had a fracture from a minor injury
- You have a gut, kidney, or liver condition affecting absorption
- You are pregnant or breastfeeding and unsure about your needs
- Symptoms persist despite more sun and dietary changes