Myths vs facts: LCT and Müdigkeit

**Myths vs. Facts: LCT and Fatigue** **Myth:** A variant in the LCT gene (lactase persistence) directly causes fatigue or low energy. **Fact:** The LCT gene controls lactase production and thus the ability to digest lactose. Lactose intolerance can cause bloating, diarrhea, and abdominal pain, but not directly fatigue. However, chronic digestive discomfort might indirectly affect sleep quality or lead to nutrient deficiencies (e.g., calcium, vitamin D) that could contribute to tiredness over time. But fatigue is a multifactorial symptom; a DNA test for LCT variants (e.g., rs4988235) only indicates the likelihood of lactose intolerance, not fatigue itself. Evidence for a direct link is weak; marketing often overstates the connection. Persistent fatigue warrants a medical workup beyond genetic testing.