Vitamin A

Vitamin A is regulators of cell and tissue growth and differentiation

Niacin is one of five vitamins (when lacking in human diet) associated with a pandemic 

deficiency disease: 

niacin deficiency (pellagra), 

vitamin C deficiency (scurvy),

 thiamin deficiency (beriberi), 

vitamin D deficiency (rickets), 

vitamin A deficiency (night blindness and other symptoms).