How are LCT and fatigue related?

The relationship between LCT (lactase gene) and fatigue is not addressed in the provided context. Scientifically, LCT variants (e.g., rs4988235) determine lactase persistence and can cause lactose intolerance. Symptoms like bloating, diarrhea, and abdominal pain after dairy intake are well-documented. However, a direct causal link to fatigue is weak. Some individuals report tiredness after consuming lactose, possibly due to malabsorption, low-grade inflammation, or secondary nutrient deficiencies (e.g., calcium, vitamin D). Studies specifically associating LCT variants with fatigue are scarce or inconsistent. Evidence is therefore mechanistic/unclear. Consumer DNA tests often overstate the clinical significance. For persistent fatigue, a comprehensive workup (iron, B12, thyroid) is more informative than a single SNP analysis.