Before considering walnuts and cancer prevention, it is important to shed some light on nutritional importance of this powerful nut.  From water to minerals, each walnut has plenty. The fresh nuts have higher water content at 20% while the dry walnuts have water content below 10% but they are both rich in nutrients.

Each walnut is rich in lipids: an average of 60%. It is therefore a good source of energy: 583.3 kcal per 100g. It also contains 11% of proteins and 10% carbohydrates. Walnuts are rich in omega-3 (12.5% fat, 7.5 g to 100 g of product), omega-6 (59% fat) and melatonin. 30 g of walnuts contain 1.1 to 1.6 g of omega-3. They also provide dietary fiber and vitamins, mainly vitamin E (23 mg / 100 g), vitamin B3, B5 and B6.  They a good source of certain minerals, mostly potassium, phosphorus and magnesium.

Nutritionally speaking and when it comes to cardiovascular disease risks, this nut is interesting the fact that its lipids are mainly polyunsaturated; 71.5% of total fats are polyunsaturated, 10.3% saturated and 18.2% mono- unsaturated. Its magnesium and fiber are recognized as protective factors against cardiovascular diseases. Several studies have found that regular walnut consumption decreases LDL cholesterol levels in the blood.

But in addition to nutritional benefits and cardiovascular health, most studies conducted on walnut prove it is a powerful anticancer food.

Walnuts and Prostate Cancer

Walnuts would slow the progression of prostate cancer, according to researchers from the University of California-Davis. The scientists published the results of their new research in the Journal of Medicinal Food. The researchers found certain molecules, other than omega-3, would be responsible for these anticancer effects. In a previous study, the researchers had shown that nuts reduced the size of prostate tumors in mice, without being able to determine whether this was due to the omega-3s found in the nuts.

To learn more about the molecules responsible for these beneficial effects, the team used a fat blend with the same content in omega-3 as walnuts. Transgenic mice models for prostate cancer were fed with either whole walnuts, walnut oil, or with control diet for 18 weeks. The results are amazing. In contrast to the control diet, diets rich in walnuts or walnut oil have slowed the growth of prostate cancer cells. That indicates that walnut components other than omega-3 would provide these benefits. The scientists believe that this is probably the combination of different anticancer compounds present in walnuts that cause the reduction and death of cancer cells in the prostate gland.

Walnuts and Breast Cancer

Regularly consumption of walnuts, at least 1 oz everyday, would reduce the risk of breast cancer, a new study published in the peer-reviewed journal “Nutrition and Cancer”. A group of researchers in Marshall University, a coeducational public research university in Huntington, West Virginia, reached this conclusion by finding in mice that fed daily consumption of 56 g of walnuts have the growth of their breast cancer slowed considerably.

“Food is a medicine”, said the lead author of the study, Elaine Hardman. She continues to say “What we eat can have a big impact on our health: it determines how the body works, and how it reacts to disease.” Among these foods that help us remain and live a cancer-free life include, walnuts. They are rich in polyphenols, natural antioxidants. They contain almost two times more antioxidants than almonds, peanuts, pistachios, hazelnuts, cashews, macadamia, pecan and Brazil nuts, according to the researchers.

Walnuts and Colorectal Cancer

The growth of colorectal tumor could be reduced by eating a handful of walnuts a day, according to another study published in The Journal of Nutritional Biochemistry. Thanks to their high content of Omega-3, walnut can reduce inflammation in cancer cells and thus slow down their development, found some researchers at Harvard Medical School (USA).

In this study, the scientists analyzed the impact of walnuts on two groups of mice with colorectal cancer. The first was given a normal diet and the other a diet rich in walnuts for 25 days. The results show walnut consumption modifies micro-ribonucleic acids (miRNAs), which control how genes adapt to environmental factors. The researchers also noted that the greater the amount of omega 3 from the nuts, the less the tumor progresses rapidly. However, further studies are needed to see if the results obtained on animals are similar in humans.

Kim H, Yokoyama W, Davis PA. TRAMP Prostate Tumor Growth Is Slowed by Walnut Diets Through Altered IGF-1 Levels, Energy Pathways, and Cholesterol Metabolism. J Med Food. 2014 Oct 29.

Dietary walnut suppression of colorectal cancer in mice: Mediation by miRNA patterns and fatty acid incorporation: Michael A. Tsoukas, Byung-Joon Ko, Theodore R. Witte, Fadime Dincer, W. Elaine Hardman, Christos S. Mantzoros

Mechanistic examination of walnuts in prevention of breast cancer. Vanden Heuvel JP, Belda BJ, Hannon DB, Kris-Etherton PM, Grieger JA, Zhang J, Thompson JT. PMID: 23061909 [PubMed] – indexed for MEDLINE.