bpc-157 health benefits peer-reviewed studies Multifunctionality and Possible Medical Application of the BPC 157 Peptide—Literature and Patent Review Therapeutic Peptides in Orthopaedics: Applications,
Description
The concern is prolonged high-dose supplementation without medical advice, or a blood test showing persistently high B12 when someone is not taking supplements

Akar S, Duran T, Azzawri AA, et al

Long-term studies into longevity are producing powerful new therapies that can drastically reduce the impact aging has on our lives
Some explore B12 for focus, concentration, or general cognitive support, although experiences vary depending on hydration, lifestyle, and individual physiology