Vitamin D deficiency occurs when your body doesn’t have enough vitamin D to maintain healthy bones, immune function, and overall health. This condition is common and can have a range of causes, symptoms, and potential complications.

Causes of Vitamin D Deficiency:

  1. Lack of sunlight exposure – especially in winter or in people who live in northern climates.

  2. Darker skin – melanin reduces the skin’s ability to make vitamin D from sunlight.

  3. Dietary insufficiency – not eating enough vitamin D-rich foods (e.g., fatty fish, fortified milk, eggs).

  4. Obesity – vitamin D can be sequestered in fat cells.

  5. Malabsorption – conditions like celiac disease, Crohn’s disease, or bariatric surgery.

  6. Kidney or liver disease – these organs are involved in vitamin D metabolism.

  7. Aging – older adults synthesise less vitamin D from sunlight.

Symptoms of Deficiency:

  • Fatigue

  • Bone pain or muscle weakness

  • Mood changes, including depression

  • Increased risk of infections

  • Slow wound healing

  • Hair loss

  • In severe cases: rickets in children or osteomalacia in adults

Diagnosis:

  • A blood test measuring 25-hydroxyvitamin D levels.

    • Deficiency: <20 ng/mL

    • Insufficiency: 20–30 ng/mL

    • Sufficiency: 30–50+ ng/mL (depending on guidelines)

Treatment:

  • Sun exposure: 10–30 minutes several times per week (depending on skin tone and season)

  • Dietary changes: Increase intake of vitamin D-rich foods

Prevention:

  • Regular, safe sun exposure

  • Eating fortified foods

  • Routine supplementation in at-risk groups (e.g., elderly, people with limited sun exposure)