“An interesting botanical extract from the avocado plant (Persea americana) is showing promise as a new cancer adjunct. When a purified avocado extract called mannoheptulose was added to a number of tumour cell lines tested in vitro by researchers in the Department of Biochemistry at Oxford University in Britain, they found it inhibited tumor cell glucose uptake by 25-75%, and it inhibited the enzyme glucokinase responsible for glycolysis. It also inhibited the growth rate of the cultured tumour cell lines. The same researchers gave lab animals a 1.7 mg/g body weight dose of mannoheptulose for five days; it reduced tumors by 65-79%,” writes Dr. Jon J. Brooks.
Not only are avocados a rich source of monounsaturated fatty acids including oleic acid, which has recently been shown to offer significant protection against breast cancer, but it is also a very concentrated dietary source of the carotenoid lutein, which is recognized by the National Cancer Institute as an antioxidant; it also contains measurable amounts of related carotenoids (zeaxanthin, alpha-carotene and beta-carotene) plus significant quantities of tocopherols (vitamin E).
Dr. Q.Y. Lu and colleagues from the University of California at Los Angeles found that, “These avocados were found to contain the highest content of lutein among commonly eaten fruits as well as measurable amounts of related carotenoids (zeaxanthin, alpha-carotene, and beta-carotene). Lutein accounted for 70% of the measured carotenoids, and the avocado also contained significant quantities of vitamin E. An acetone extract of avocado containing these carotenoids and tocopherols was shown to inhibit the growth of both androgen-dependent (LNCaP) and androgen-independent (PC-3) prostate cancer cell lines in vitro. Incubation of PC-3 cells with the avocado extract led to G2/M cell cycle arrest accompanied by an increase in p27 protein expression.”
The researchers concluded, “In common with other colorful fruits and vegetables, the avocado contains numerous bioactive carotenoids. Because the avocado also contains a significant amount of monounsaturated fat, these bioactive carotenoids are likely to be absorbed into the bloodstream, where in combination with other diet-derived phytochemicals they may contribute to the significant cancer risk reduction associated with a diet of fruits and vegetables.”
 Journal of Nutritional Biochemistry (Inhibition of prostate cancer cell growth by an avocado extract: role of lipid-soluble bioactive substances. J Nutr Biochem, 2005; 16(1):23-30).