Indeed, in humans, SSRIs only elevate serotonin release (and hence activity) moderately, inconsistently, and with a delay (38-40) - which could, in part, explain why SSRIs (and SNRIs) treat depression, OCD, and other mood disorders modestly, inconsistently, and with a delay (41-43)
Alternative splicing of glutathione S-transferases
Some plant-based milks, cereals, and nutritional yeast are fortified with B12, which can certainly help
Electrospray ionization in positive mode and multiple reaction monitoring are applied for detection
PMC3385825 DailyMed
Persistent symptoms or no measurable change after a full cycle is a sign to reassess