Amino acids are crucial for cell culture. Cells cannot synthesize essential amino acids which have to be added to cell culture, while non-essential-amino acids relieve the intracellular metabolism and help cells grow better under the same circumstances. The availability of vitamins is extremely important for the cells, since the cells usually cannot synthesize the vitamins. Vitamins act as co-factors for many enzymes and are essential for their function. The absence of vitamins in culture may lead to decrease in cell growth, cell death or loss of productivity.