The good news is, rats on a diet rich in berries developed only half as many tumors as rats in the control group, after both were injected with carcinogenic chemicals. The even better news is, ordinary berries were just as good as their more expensive cousins.
Nearly all of the rats on standard rat chow developed esophageal cancer after exposure to five weeks of exposure to N-nitrosomethylbenzylamine. Only 60 to 75 percent of the rats on high-berry diets developed cancer at all, and they had fewer and small tumors. The berries tested were:
1. Red raspberries
2. Black raspberries
3. Strawberries
4. Blueberries
5. Noni berries
6. Acai berries
7. Wolfberries (also called goji berries)
Each berry-enriched diet contained 5 percent of one type of berry in dehydrated form. Results were similar for each type of berry.
Two cancer-fighting compounds, ellagitannin and anthocyanin, were identified earlier in raspberries. The new results indicate that other factors are important too, since the berries tested have different levels of these compounds. Researchers measured the levels of inflammatory cytokines in the experimental rats to gain insights into what the berries are doing. They found reduced levels of interleukin 5 (IL-5) and the rat analog of interleukin 8 (IL-8), and suggest that these two cytokines may predict the cancer-preventing effects of nutritional products.
In a related study, researchers found that berries prevented breast cancer in a rat model. Tumors were induced by high doses of estrogen. Diets containing 2.5 percent black raspberry, 2.5 percent blueberry, or 400 ppm ellagic acid reduced the tumor incidence (10 to 30 percent), size (41 to 67 percent), and multiplicity (38 to 51 percent). The authors suggest that berries act prevent development of breast cancer by suppressing levels of estrogen-metabolizing enzymes.
Both these studies are reported in a recent issue of Science News. The work was done at Ohio State University (esophageal cancer study) and University of Louisville, Kentucky (breast cancer study). I hope to see more research on what makes berries so effective against cancer. In the meantime, I will definitely increase the amount of berries in my diet!
References:
Nathan Seppa, “Many berries show cancer promise”, Science News 2010 July 17; 178(2): 10.
Stoner GD et al, “Multiple berry types prevent N-nitrosomethylbenzylamine-induced esophageal cancer in rats”, Pharm Res 2010 Jun; 27(6): 1138-45.
Aiyer HS et al, “Berries and ellagic acid prevent estrogen-induced mammary tumorigenesis by modulating enzymes of estrogen metabolism”, Cancer Prev Res (Phila Pa). 2010 June; 3(6): 727-37.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.