M.Tech. / Natural occurring components in human breast milk, cow milk and soy milk have shown anticarcinogenic abilities. The human breast milk protein, -lactalbumin, was found to induce apoptosis in cancer cells, embryonic cells and rapidly growing cells, when converted from its native form to a partial denatured apoptotic-inducing form. Moreover, radiation may cause irreversible changes of protein conformation at the molecular level. Native -lactalbumin is one protein that has shown a decrease in aromatic amino acid concentration and the formation of high and low molecular weight fractions when exposed to high doses of ionizing radiation. The effect of human breast milk, cow milk, soy milk and galactose (positive control) on SNO, A549 cancer cells and normal lymphocytes were investigated. Human breast milk was irradiated with low doses of Co60 ionizing radiation (0.1Gy, 1.0Gy and 5.0Gy) in order to establish the effect of these doses on the apoptotic-inducing ability of human breast milk. The techniques used included, Trypan blue dye exclusion (cell viability), haematoxylin and eosin stain (cell morphology), modified comet assay (halo) (DNA damage) and flow cytometry (apoptosis and necrosis). Findings showed that human breast milk, irradiated human breast milk and galactose induced apoptosis in the SNO, A549 cells and lymphocytes. The cell viability, cell morphology and DNA fragmentation patterns of irradiated human breast milk were similar to that of non-irradiated human breast milk, although the flow cytometry results did not correlate. Cow and soy milk did not induce apoptosis in the SNO, A549 cells and lymphocytes. The modified comet assay (halo) detected DNA damage as apoptotic or necrotic cells. A clear distinction could not be made between the two cell populations using this assay. Flow Cytometry discriminated and quantified apoptotic cells and necrotic/late apoptotic cells using Annexin V and Propidium Iodide (PI), respectively.