Palm vitamin E, tocotrienols in particular, are known to exert great anti-cancer effects on a variety of cell types. In this study, the effects of palm vitamin E, carotenoids, squalene and coenzyme Q10 were studied on two human breast cancer cell lines. All compounds caused anti-proliferative effect in vitro but tocotrienols (compounds and isomers) were generally more potent. The results show that the anticancer effects of palm vitamin E were more pronounced when these were used on their own rather than in combination with other phytonutrients (carotenoids, squalene and coenzyme Q10). The palm phytonutrient complex, which contains all the tested phytonutrients did not appear to exert better antiproliferative effects compared to the individual compounds. Our results show that tocotrienols, as well as other phytonutrients (carotenoids, squalene and coenzyme Q10), have anti-proliferative effects on breast cancer cells but different and antagonistic mechanisms may be employed in combination.