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Walnuts and Health

Cancer

Unique among nuts, walnuts contain the highest amount of alpha-linolenic acid (ALA), the plant-based omega-3 fatty acid, required by the human body. The ALA, phytosterols, vitamin E and melatonin found in walnuts prompted researchers to conduct a pilot animal study.

The study, published in Nutrition and Cancer¹, investigated whether consumption of walnuts could affect growth of human breast cancer tumors (MDA-MB 231) implanted into mice.

Methods:

• The pilot animal study included 40 mice with human breast cancer tumors which were divided into two groups. One group was fed ground walnuts daily (18 percent of caloric intake) in the amount equivalent to one ounce or 1/4 cup (28 grams) for humans, while the comparison group consumed a diet supplemented with corn oil, along with amounts of vitamins, minerals and fiber that were similar to the amounts occurring in the walnut diet.

Results:

• After 35 days, the breast cancer tumors of the walnut fed mice were significantly less (2.9 ± 1.1 mm3/day) – about half the size of the tumors – than in the mice that were not fed walnuts (14.6 ± 1.3 mm3/ day).
• The researchers concluded that the results of this pilot study demonstrate that consumption of walnuts could slow the growth of cancers possibly by slowing the growth of tumor cells; however more research is needed before understanding its application to humans.