B vitamins play a major role in producing energy in the cells, but they certainly aren't top gun. They are converted in the body to act as coenzymes.
As coenzymes they have almost no independent catalytic power because they must rely on being temporarily bound as organic prosthetic groups to an apoenzyme, then called a holoenzyme (1p643).
In a very complex reaction of three enzymes and five coenzymes, four B vitamin-derivative coenzymes act in synergy with yet another coenzyme (lipoamide) to produce pyruvate dehydrogenase complex (1p750).
Thus, any deficiency of the four B vitamins—thiamine, riboflavin, niacin, and pantothenic acid—could severely impact cellular respiration.(1p750)
You could think of pyruvate dehydrogenase complex as a fighter jet equipped with B vitamin wingmen. The pilot is its substrate pyruvate, which later develops into that maverick of a central charcter in the citric acid cycle, acetyl CoA (1p751).
1. Denniston KJ, Topping JJ, Caret RL. General, Organic, And Biochemistry, 5th ed. New York: McGraw Hill; 2007.