Research-only peptides (BPC-157, TB-500, melanotan-2, most GH secretagogues) are sold labeled "for research purposes only" and "not for human consumption." Quality control depends entirely on the vendor
This usually occurs in individuals with underlying digestive conditions, those who have trouble absorbing all nutrients through digestion, or those with pernicious anemia, which specifically prevents B12 absorption
In addition, a vitamin B12 deficiency can trigger hair loss, memory impairment, depressive mood and other symptoms
But the jump from C57BL/6 mice to humans involves differences in metabolic rate, NNMT tissue distribution, adipose tissue physiology, and drug metabolism that preclinical data cannot address