An adequate supply of these water-soluble vitamins is required for the optimum function of various cells and tissues.Except for Vitamin B12, these water-soluble vitamins are not stored in the body to any significant extent, the excess quantities being excreted in the urine. Therefore, a regular and adequate intake of them is necessary to meet the metabolic requirements. Deficiencies of water-soluble vitamins often co-exist because of their overlapping dietary sources and metabolic interdependence. Initially the deficiency of these vitamins may be subclinical and demonstrable only by means of biochemical tests. If not corrected at this stage, it may become manifest as various symptoms, including impaired wound healing and increased susceptibility to infection. Classical deficiency diseases such as beri beri, pellagra and scurvy are rare, whereas mild and subclinical deficiencies are probably more common, even among apparently healthy individuals.