Vitamin B complex supplies a nutrient or bioactive compound intended to alter a defined physiological pathway. The relevant form, baseline status and product quality determine whether the proposed mechanism is clinically meaningful.
What it is, why people use it, the evidence, and what to know before trying it.
Known side effects, interactions and use limits from reviewed sources.
B-complex formulas vary widely. Excess vitamin B6 can cause neuropathy, niacin can cause flushing or liver injury, and folic acid can mask vitamin B12 deficiency.