Background: China accounts for about half of the global annual death toll firom stomach cancer and this malignancy remains the second leading cause of death from cancer worldwide.There is considerable epidemiological evidence linking various dietary factors with a reduction in the incidence of stomach cancer.Frequent consumption of vegetables and fruits rich in vitamin C may reduce the risk of gastric cancer.Dietary intake of calciurn or carotene have been negatively associated with stomach cancer risk The first large rundomised trial on antioxidants and cancer risk was the Chinese Cancer Prevention Study, published in 1993 showing that a combination of beta-carotene, vitamin E and selenium significantly reduced the risk of gastric cancer.Aim: To examine the ability of synthetic peptides based on a commonly ingested dairy protein to inhibit cancer cell proliferation in vitro.Methods: MKN45 (stomach) and HT29 (colon) cancer cell lines were obtained from the Cancer Research Laboratory, University of New South Wales, and American Type Culture Collection, respectively.In vitro cell proliferation was assessed using the MTT assay.Mass spectroscopy was used to determine resistance of peptides to cleavage by a simulated gastrointestinal environment.Results: Growth experiments performed with short synthetic peptides based on the sequence of a commonly ingested dairy protein revealed a peptide that inhibited in vitro growth of not only gastric cancer but also colon cancer cells.This peptide remained un-cleaved when exposed to a simulated gastrointestinal environment whereas an extended form of the peptide, when exposed to the same conditions, yielded increasing amounts of the active anticancer fragment with increasing time.Conclusion: Nutripep Ptys discovery can be developed as either a functional food or nutritional supplement provided as tablets, powder or other form.The compound could also be used in a wide range of food types not restricted to the dairy industry.