Walnut Proteins Found Toxic to Breast Cancer Cells
If you were looking for yet another reason to add walnuts to your regular diet, this could be it. Scientists have learned that walnut proteins are toxic to cancer cells. More specifically, a lab study found that walnut proteins slowed the growth of metastatic human breast cancer cells (MDA-MB-231) by 75%. We already knew that walnuts were packed with healthy fats, fiber and powerful antioxidants. But this was a very unexpected finding. And it helps to explain why walnuts are one of the most powerful anticancer foods in our diet.
Walnuts: An Established Anticancer Superfood
A recent study from Spain showed walnuts to be the most powerful of all nuts at lowering cancer risk. Those getting at least three servings weekly had an incredible 54% reduced risk for cancer mortality (from all cancers combined), while those getting at least three servings weekly of other nuts had a risk reduction of just 25%. Note that one serving of nuts is 28 grams or about one ounce. So why are walnuts so much more powerful than other nuts? First of all, they have by far the highest amounts of antioxidants of any nuts—just one serving delivers the equivalent antioxidant power of 2,200 mg of vitamin C. The most important antioxidants in walnuts are ellagitannins and gallotannins, which are otherwise hard to find in the diet. Ellagitannins also serve many biological functions beyond quenching free radicals. Besides being a powerful anti-inflammatory, they moderate blood sugar and cholesterol levels, improve fat metabolism and appear to protect brain cells. Strawberries are another major source of ellagitannins and have been linked with reduced risk of several cancers. Walnuts are also unique among nuts in that their fat is 10% alpha-linolenic acid—the same omega-3 fat found in flax seed oil and also linked to reduced cancer risk in several population studies. So it makes perfect sense that walnuts themselves would also be linked to powerful risk reductions. But the finding that walnut proteins also fight cancer was completely unexpected.
A Surprise Finding: Walnut Proteins Fight Cancer Too
Researchers simulated what would happen to walnuts in the human stomach by partially digesting their proteins with enzymes. The results were protein fragments called peptides. When the peptides were added to human breast cancer cells in a test tube, their growth was slowed by up to 75%. Lab studies like this offer some key insights into how a food might fight cancer, but caution is warranted in extrapolating lab studies to humans. We simply don’t know yet if walnut proteins would fight breast cancer the same way in women. But given the fact that walnuts have already been linked to reduced risk for all cancers combined, this study provides new intriguing evidence for how walnuts are fighting cancer. Walnuts are about 15% protein by weight, meaning that a single serving would contain 4 grams (4,000 mg) of protein. In comparison, one serving would also deliver other anticancer compounds at levels of just a few hundred milligrams—far less than the quantity of protein. That makes fighting cancer by walnut protein a real possibility. It’s also another reminder that eating the whole food rather than concentrated supplements is the best way to achieve optimal health.
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