For example, if youre experiencing nausea, constipation, or other symptoms that are significantly interfering with your quality of life, thats your cue to talk to your healthcare provider
But some nutrients have a more complicated story, and vitamin B12 is a fascinating example

Volkova A et al., 2016 [PubMed] Key Areas of Research: Molecular Tuftsin receptor binding characterization, GABAergic gene expression profiling, peptide structural stability assays in biological matrices, angiotensin-converting enzyme interaction mapping, enzymatic cleavage resistance characterization Cellular / Neurochemical GABAergic signaling pathway characterization, inhibitory neurotransmission parameter assessment, neuroblastoma cell line gene expression profiling, GABA receptor interaction modeling, anxiolytic-relevant receptor system characterization in preclinical settings Systemic (Preclinical) Behavioral parameter measurement in anxiety-relevant preclinical models, cytokine pathway modulation monitoring, neuroimmune axis interaction characterization, inhibitory signaling system profiling in controlled investigational settings Together, these findings suggest broad experimental potential for Selank across GABAergic neurotransmission, neuroimmune signaling, and preclinical anxiety-model research pathways

There are many mast cells near the BBB