What role does LCT play in fatigue?

The provided context does not contain any direct information linking the LCT gene to fatigue. LCT encodes lactase, the enzyme that digests lactose. Variants (e.g., rs4988235) determine lactase persistence. Lactose intolerance can cause gastrointestinal symptoms like bloating, diarrhea, and abdominal pain after lactose consumption. Fatigue is not a classic symptom, but could theoretically arise secondary to malabsorption, nutrient deficiencies, or chronic low-grade inflammation. However, the evidence for a direct causal role of LCT in fatigue is weak and not supported by the given sources. A conservative conclusion: LCT variants alone do not explain fatigue; other lifestyle and health factors are more influential. Note: The context lacks any studies or mechanistic data on LCT and fatigue.