Myths vs facts: Vitamin D 25-OH and Sport

The relationship between vitamin D (25-OH) and sport is complex. Vitamin D acts via the VDR receptor and may influence muscle function. However, a DNA test for VDR variants (e.g., rs2228570) only reveals receptor genetics, not actual 25-OH blood levels. Studies on vitamin D supplementation and athletic performance are mixed: in deficiency, supplementation can improve muscle strength and bone health, but in replete individuals, extra vitamin D does not enhance performance. Evidence is mostly mechanistic and observational; large RCTs are lacking. An optimal vitamin D level for athletes is not clearly defined. A DNA test alone cannot diagnose deficiency – a 25-OH blood test is required. MyBody-X offers such blood tests, but interpretation should be done by a physician. In summary: vitamin D is relevant for athletic health, but myths about performance enhancement in normal-range individuals are not evidence-based. Be cautious about overinterpreting genetic tests.