Medical research into peptides began in the 1920s and led directly to insulin therapy for diabetics
That opened a clearer pathway for 503A compounding pharmacies to fill prescriptions from licensed clinicians
Several drugs, including colchicine, have been reported to reduce the absorption of methylcobalamin, vitamin B12
Of course, older adults, people over age 50 in particular, tend to have the lowest B12 levels, though vegetarians and those who have undergone gastric bypass surgery are also at a higher risk
People with GI conditions (such as chronic diarrhea, celiac disease, Crohn's disease, and ulcerative colitis) or who have had procedures like gastric bypass surgery that impair nutrient absorption are also at greater risk