Brain function: Brain fog, memory problems, cognitive impairment, insomnia, headaches (especially migraine), behavioural changes, learning problems, nominal aphasia Mood: Mood swings, irritability, depression, anxiety, hallucinations, delusions, psychosis Sensory: Peripheral paraesthesia (pins and needles), numbness, neuropathic pains, poor balance, reduced vibration sense or proprioception (joint position sense), tinnitus, ataxia, taste impairment, sometimes myelopathy Constitutional: Fatigue, anaemia (either macrocytic, or normocytic when also iron deficient or associated with thalassaemia minor), other cytopenia, abdominal complaints, malabsorption, failure to thrive, weight loss, diarrhoea, hyperpigmentation, glossitis, (aphthous) stomatitis, infertility, urinary tract infections Motor: Muscle weakness, altered reflexes (increased in degeneration of the spinal cord, reduced when peripheral neuropathy dominates), spasticity, seizures, cardiomyopathy Autonomic: Urinary and/or faecal incontinence, postural hypotension or dizziness, erectile dysfunction Diagnosing B 12 deficiency can be challenging because no single specific measurement exists to reliably diagnose or refute the presence of B 12 deficiency 11 12 26 27 (box 2)

Biologic therapies require careful handling during medication preparation
Interest in BPC-157 has grown due to its reported benefits in tissue healing, gut protection, and inflammation control
It is not dangerous if you go with a guide and at a good pace
High activity was further verified using the fluorogenic FS6-QPQL substrate (Appendix Fig