Walnut consumption slows growth of MDA-MB 231 xenografts.

B157

Walnuts contain a high level of omega 3 fatty acids (18C, α-linolenic acid, ALA), of phytosterols, Vitamin E and melatonin. The results of numerous studies show that consumption of long chain omega 3 fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) can slow cancer growth. Dietary phytosterols and antioxidants (i.e. vitamin E and melatonin) can also slow cancer growth. Thus, individually or in combination, these components of walnuts have a potential for slowing cancer growth. A study was devised to determine whether consumption of walnuts could effect growth of MDA-MB 231 human breast cancers implanted into nude mice. One million MDA-MB 231 cells were injected subcutaneous between the scapula of 40 nude mice that were consuming an AIN-76A diet slightly altered to contain 10% corn oil. After the tumors reached a measurable size (3-5 mm diameter), the tumor bearing mice were divided into two groups such that the mean tumor size of each group was the same with equal numbers of larger and smaller tumors. The diet of one group of mice was changed to contain ground walnuts. Each mouse consumed the human equivalent of 1 oz of walnuts per day. The diets were balanced to contain equal amounts of protein, carbohydrate, fat and fiber. Tumors were measured and mice were weighed 3 times per week. About 10 days after the diet change, tumor sizes began to diverge. Linear regression analyses from day 10 until the end of the study showed that the growth rate of tumors of the group that consumed walnuts was significantly less than that of the group that did not receive walnuts in the diet. At the end of the study, the mean size of the tumors of the group that consumed walnuts was ½ the mean size of the tumors of the group that did not consume walnuts. The EPA and DHA content of the liver and fat of the group that consumed walnuts was significantly higher than that of the group that did not consume walnuts indicating that the ALA was efficiently converted to EPA and DHA. Additional analyses are ongoing.