Vitamins are essential substances that, with rare exceptions, the body cannot produce on its own, so we must consume them either with food or in the form of supplements. Each vitamin has a specific function in the body and consuming optimal amounts results in optimal functioning of our body. Vitamins are involved in controlling and regulating important reactions in our body. Vitamin A acts as a regulator of growth and differentiation of cells and tissues, Vitamin D acts similarly to hormones, regulates the metabolism of minerals for bones and other tissues. B-complex vitamins act as cofactors in enzymatic reactions (coenzymes), and vitamins C and E act as antioxidants and thus protect our cells from oxidative stress.