Vitamin D deficiency: symptoms, risks, and optimal levels

Vitamin D plays a critical role in bone metabolism by promoting the absorption of calcium and phosphate. A deficiency can lead to various health issues, including bone deformities, rickets in children, osteomalacia, and osteoporosis.

Common symptoms of low vitamin D levels may include increased fatigue, bone or back pain, muscle weakness, increased susceptibility to illness due to impaired immune function, and mood changes such as depression.

Optimal vitamin D levels are measured via blood tests, specifically looking at 25-hydroxyvitamin D [25(OH)D]. While reference ranges vary between organizations like the Robert Koch Institute (RKI) and the US Institute of Medicine (IOM), the RKI suggests that a value between 30 and 50 ng/ml is optimal. Low levels (below 12 ng/ml) are associated with significant deficiency risks.