B-complex

A B-complex bundles the eight B vitamins, which act as cofactors across energy metabolism. Because they release energy from food, they are marketed as 'energy' vitamins — but they do not add energy to someone who already has enough of them.

Their value is in correcting a broad B-vitamin shortfall, which can occur with poor diets, heavy alcohol use, some medications or malabsorption. They are water-soluble and generally safe (watch high-dose B6 over the long term); for most people food covers needs.

Sources

• PubMed: vitamin B complex supplementation energy fatigue deficiency (research overview)