Vitamin b complex with vitamin b1 b2 b3 b6 b12 supports normal energy yielding metabolism contributes to the reduction of tiredness fatigue holland barrett complete b vitamin b complex provides an excellent source of b vitamins to support normal energy yielding metabolism and the reduction of tiredness and fatigue thiamin b1 riboflavin b2 niacin b3 and vitamins b6 and b12 also contribute to the normal functioning of the nervous system vitamin b complex with vitamin b1