e421 Yang WS, SriRamaratnam R, Welsch ME, Shimada K, Skouta R, Viswanathan VS, et al
Following a vegan or vegetarian diet, having gastrointestinal issues, having pernicious anemia, and taking specific drugs are issues that frequently result in a deficiency
Glutathione IV therapy may be the answer
Medi-Peel products do exactly that
The hair-growth interest comes from a line of animal research: T4 was shown to increase hair growth in rats and mice by activating hair-follicle stem cells in the bulge region, per PubMed (Philp et al., 2003, DOI), with follow-up work showing faster regrowth in T4-overexpressing mice and slower regrowth in knockout mice via VEGF and P38/ERK/AKT signalling (Gao et al., 2015, DOI)