What to watch with LCT and Müdigkeit?

The question about LCT (lactase gene) and fatigue is understandable, but the scientific evidence for a direct link is weak. LCT variants determine lactase persistence – whether you can digest lactose after infancy. Lactose intolerance typically causes gastrointestinal symptoms like bloating, diarrhea, and cramps. Fatigue is not a classic symptom, though some individuals report feeling tired after consuming dairy, possibly due to malabsorption or low-grade inflammation. However, no robust clinical studies confirm a causal relationship. Consumer DNA tests (e.g., from MyBody-X) can identify your LCT genotype, but they cannot diagnose lactose intolerance or fatigue. If you experience persistent tiredness, consider other common causes (iron deficiency, thyroid issues, sleep quality) before attributing it to dairy. Evidence grade: weak to moderate (observational, no controlled trials).