This information is from the American Institute of Cancer Research:
Evidence has been found that a daily dose of walnuts reduces the growth of breast cancer tumors in mice. Their study is the first to investigate the effect of walnut consumption on cancer. The human equivalent to what the mice ate would be to eat 14 walnuts every day.
“This is an intriguing finding that needs to be repeated, and ultimately confirmed in humans...but it fits with some of what we’ve seen from other studies. We know that walnuts have a lot to offer, such as omega-3 fat, vitamin E, and other antioxidants. Many of these substances have already shown anti-cancer potential individually” says Karen Collins, Nutrition Advisor for AICR.
A group of 22 mice with human breast cancer tumors was divided into two groups. The test group was fed ground walnuts daily and the control group consumed a diet supplemented with corn oil, vitamins, minerals and fiber that were similar to the amounts occurring in the walnut diet.
After a month, the tumors of the walnut-fed mice were only about half the size of the tumors in the mice that were not fed walnuts.
Walnuts are one of the few plant foods that contain this kind of omega-3 fat, which protects against heart disease, inflammation and, hopefully, cancer as well.
Studies suggest that omega-3 fats exert their influence by increasing the production of hormone-like, anti-inflammatory compounds. There is growing evidence that inflammation plays a role in the development of cancer.
Other much-studied cancer-protective substances within walnuts include gamma-tocopherol (a form of vitamin E), phytosterols and flavonoids. Lab studies have shown that these compounds may slow cancer cell growth and fight inflammation.
A Healthy, but Calorie-Dense, Food Walnuts also contain fiber, which studies have shown can help with weight control. One caution, notes AICR’s Collins, is that walnuts pack a lot of calories into a relatively small portion.
Because walnuts have their own calories, it’s best to substitute them for other foods so you don’t end up gaining unnecessary weight.