Is LCT useful for Sport?

The usefulness of the LCT gene for sport is not straightforward. LCT encodes lactase, the enzyme that breaks down lactose. Genetic variants causing lactase persistence or non-persistence influence dairy tolerance. For athletes, especially endurance athletes, consuming dairy products may cause gastrointestinal distress (bloating, cramps, diarrhea) if lactose intolerant, potentially impairing performance. However, the effect is highly individual and depends on gut microbiome adaptation and habitual intake. There is no strong evidence that LCT genotype directly enhances or hinders athletic performance. The evidence level is mechanistic: plausible biological link but lacking robust human studies. Athletes with lactose intolerance can choose lactose-free dairy or avoid dairy without negative performance effects. A DNA test alone is not actionable for sport optimization.