The time it takes for vitamin B12 to become effective depends on personal characteristics, together with the selected supplementation method
Aging is accompanied by BBB breakdown, and instead of being region-specific as in neurological diseases (e.g., hippocampus in Alzheimers disease), it is zonation-specific (capillaries are more affected than other vessel types) (Zhao et al., 2020)
Same for the types of stem cells sold by unproven clinics
Pentadecapeptide BPC 157 Enhances the Growth Hormone Receptor Expression in Tendon Fibroblasts, Chang CH, Tsai WC, Hsu YH, Pang JH, Molecules, 2014 Nov 19;19(11):1906619077
In a cell culture replicon assay, the A5328S/V and S6799A substitutions did not affect nirmatrelvir activity (EC50 value fold changes were 0.3/0.2 and 0.7, respectively)