In a recent study published in the Journal of Nutritional Biochemistry a research team led by Dr. Christos Mantzoros from Beth Israel Deaconess Medical Center, Harvard Medical School found that a diet containing walnuts might slow the growth of colorectal tumor by changing cancer genes.
The study titled “Dietary Walnut Suppression of Colorectal Cancer in mice: mediation by miRNA patterns and fatty acid incorporation“, is the first research investigating how the consumption of walnuts alters micro-ribonucleic acids (miRNA), nucleotides involved in changes in gene expression. Recently, miRNAs have been a research focus in the field of epigenetics, the study of how environmental factors have the capacity to alter genes.
“Our research demonstrates that a walnut diet causes significant changes in the expression profile of miRNAs in localized colorectal cancer tissue, and that a walnut diet incorporates protective fatty acids in the colonic tumor either through its direct effects or through additive or synergistic effects of multiple other compounds present in walnuts,” said Dr. Mantzoros in a recent news release. “While future studies are needed, we’re optimistic of the role of miRNAs as biomarkers of disease and prognosis, and may demonstrate a potential therapeutic target for colorectal cancer treatment.”
In this research two groups of mice were randomized, and while one group was fed with 2 ounces of walnuts per day the second group was fed with an identical control diet without walnuts. After a period of 25 days the team verified that in mice fed with walnuts, key miRNAs affecting cancer cell proliferation, inflammation and vascularization (blood supply) were actively involved.
Compared to mice that did not ingest walnuts, tumours of animals fed with walnuts had 10 times the amount of total omega-3 fatty acids, including alpha-linolenic acid (ALA). Results also showed that a small tumor size was related with a higher percentage of omega-3 in tumor tissues, indicating that ALA provides a protective effect. In comparison with the group of mice that were not fed with walnuts, mice who ingested it had a slower rate of tumor growth. However, these results cannot be directly implied for humans.
ALA is a fatty acid known to reduce inflammation. Walnuts contain a significant source of alpha-linolenic acid (ALA), and also antioxidants, minerals and vitamins. Over the last years, evidence has shown that colorectal cancer, the third most common type of cancer worldwide, can be prevented by diet and other lifestyle changes.