Plant flavonoids are polyphenolic compounds, commonly found in vegetables, fruits and many food sources that form a significant portion of our diet. These compounds act as anticancer and anti-proliferative but after interaction with milk proteins they form complexes which become less effective than these compounds alone. Investigation has been conducted to delineate the action of some phenolic compounds of natural origin and complexes formed from interactions between phenolic compounds and milk proteins in three human tumors cell lines: Breast (MCF7), Liver (HePG2) and colon (HCT116), these interactions were studied by fourier transform infrared spectroscopy (FTIR). Phenolic compounds have positive effect on human cancer cell lines but after interaction with milk protein and forming complexes, they become less effective than phenolics and some time have negative effect and become pro-cancer; this interaction can be studied by (FTIR) to know which groups do this complex. The spectra were recorded under conditions generally applied in quantitative work. IR spectra were recorded in the region from 4000-250 cm-1 , but the bands in the region 4000-1400 cm-1 were analyzed in detail, since they are characteristic of OH groups while NH groups appeared at (3000-4000 cm −1) of various protonic species that undergo hydrogen bonding interaction. Another region of interest was the region from 1800-1400 cm-1 , characteristic of the bending vibrations of the same group. Since the bands in this region were wide and complex.