What to watch with FUT2 and sleep?

The FUT2 gene variant determines secretor status and influences vitamin B12 absorption and gut microbiome composition. Some studies suggest a link between the gut microbiome and sleep quality, but direct evidence for FUT2 and sleep is very weak. Most data come from mechanistic or observational studies with small effect sizes. There are no robust clinical recommendations based on FUT2 results for sleep. A deficiency in vitamin B12 could indirectly affect sleep, but this is not FUT2-specific. Therefore, one should not draw premature conclusions or purchase expensive supplements solely based on a FUT2 test. The predictive power of such genetic tests is limited, and lifestyle factors like sleep hygiene, stress, and diet dominate. Be cautious of marketing claims that suggest a direct effect on sleep.