Myths vs facts: FT3 and Darmgesundheit

The question of myths vs facts regarding FT3 (free triiodothyronine) and gut health is not directly addressed in the provided context. It is known that the gut microbiome can influence thyroid hormone metabolism – for example, bacterial enzymes may modulate deiodination of T4 to T3. However, the evidence is largely mechanistic and derived from animal studies; robust human trials are lacking. A direct causal link between FT3 levels and specific gut bacteria is not established. Myths such as 'Low FT3 proves gut dysfunction' or 'Gut cleansing cures thyroid issues' are not scientifically supported. FT3 should always be interpreted alongside TSH, fT4, thyroid antibodies, and clinical symptoms. Gut health is one factor among many. Without strong human evidence, the utility of home microbiome tests for thyroid assessment remains limited. Evidence grade: unclear (no direct sources in context).