Vitamin D deficiency and supplementation guidelines

Vitamin D, often referred to as the ‘sun vitamin,’ plays a critical role in calcium and phosphate metabolism, bone strength, muscle function, and the immune system. While the body can produce it through UVB exposure, dietary intake only covers a small portion of daily requirements.

Risk groups for deficiency include individuals with limited mobility, those who spend little time outdoors, people with darker skin pigmentation, and individuals with certain chronic conditions affecting the gastrointestinal tract, liver, or kidneys. Certain medications, such as antiepileptics or cytostatics, may also impact levels.

In regions like Germany, sufficient sunlight for natural synthesis is typically only available from March to October. During winter months, the body relies on reserves stored in fat and muscle tissue. Because both deficiency and excessive dosage can lead to health complications, medical professionals recommend blood tests to determine actual levels before starting supplementation.