 We related this inhibitory activity to a selective depletion of intracellular glutathione synthesis.The use of humanized whey protein concentrate as a food supplementation may have direct implication in clinical trials with adjuvant chemotherapy.Glutathione (GSH) accounts for more than 90% of total intracellular non-protein sulfhydryl and is critical in a variety of cellular defense functions including protection from toxic oxygen species and detoxification of various xenobiotics.