Thanks, may have missed it but don't see how they define the hypothyroid non-levo population. I'd guess if they are not on any medication that they are probably less severely hypothyroid than the levothyroxine users to begin with which might explain the apparent worse outcomes with levo. Nevertheless we know that levo is often not used rationally and can suppress metabolism further when overdosed. Possible that the common advice to take levo on an empty stomach is also contributing to problems since its been noted to lead to abnormal hunger, stomach pain and weight gain.I'm not familiar with it, but there's '(5R)-[(1S)-1,2-dihydroxyethyl]-3,4-dihydroxyfuran-2(5H)-one'.
"Hypothyroidism and levothyroxine therapy are the most strongly associated to SIBO in our cohort. A case control study by Lauritano et al[27] has already revealed a high prevalence of SIBO in patients with autoimmune thyroiditis and hypothyroidism, but the influence of the autoimmune process was a questionable biasing factor. Multivariate analysis confirmed that levothyroxine therapy is a stronger predictor of SIBO than hypothyroidism. The underlying mechanism is unclear. One might speculate that hypothyroidism leads to hypomotility, but, surprisingly, levothyroxine therapy was even more associated to SIBO and not able to reverse the effect of hypothyroidism."
@Collden @Wilfrid
My take-home message would be that hypothyroidism is bad for SIBO and getting it properly treated is important to resolve it.