Diet components can suppress inflammation and reduce cancer risk

Abstract

Epidemiology studies indicate that diet or specific dietary components can reduce the risk for cancer, cardiovascular disease and diabetes. An underlying cause of these diseases is chronic inflammation. Dietary components that are beneficial against disease seem to have multiple mechanisms of action and many also have a common mechanism of reducing inflammation, often via the NFκB pathway. Thus, a plant based diet can contain many components that reduce inflammation and can reduce the risk for developing all three of these chronic diseases. We summarize dietary components that have been shown to reduce cancer risk and two studies that show that dietary walnut can reduce cancer growth and development. Part of the mechanism for the anticancer benefit of walnut was by suppressing the activation of NFκB. In this brief review, we focus on reduction of cancer risk by dietary components and the relationship to suppression of inflammation. However, it should be remembered that most dietary components have multiple beneficial mechanisms of action that can be additive and that suppression of chronic inflammation should reduce the risk for all three chronic diseases.

Keywords: Cancer; NFκB; inflammation; plant based diet; walnut.

Fig. 1

Polyphenol classifications. Classes of polyphenols and their relationships to each other. The top line of each class gives the general class name, examples of the class follow.

Fig. 2

Growth of MDA-MB231 human breast cancers in nude mice consuming diets with or without walnut. Graph shows the average volume of MDA-MB 231 human breast cancers implanted in nude mice consuming a diet either with or without walnuts. Tumor were grown to about 50mm³ volume before diet change. Day 0 is the day of diet change. The 'corn oil' group consumed the AIN-76 based diet, the 'walnut' group had the AIN-76 formula adjusted to include a human equivalent of 2 ounces of walnut per day. N = 11 per group. Non-linear regression analyses (Prism©) showed that tumors of the 'corn oil' group grew significantly faster than those of the group that consumed walnut, P = 0.001. The doubling time of the corn oil group was 16 days whereas the doubling time of the walnut group was 23.3 days.

Fig. 3

Tumor incidence and multiplicity at 145 days of age in mice that consumed diets that did or did not contain walnut. Tumor incidence (fraction of mice with any tumor) and tumor multiplicity (number of mammary glands with any tumor) in C3(1) TAg mice. The group designations are mother diet/pup diet thus: CO/CO - mother and pup consumed corn oil diet; CO/walnut - mother consumed corn oil diet/pup consumed walnut containing diet; Walnut/Walnut - mother and pup consumed walnut containing diet; Walnut/CO - mother consumed walnut diet, pup consumed corn oil diet. N = 10 to 13 mice per group. Pups that were exposed to walnut in the diet throughout life had significantly fewer tumors than those that did not receive walnut. Groups with different letters are significantly different, P < 0.05, (Prism© was used for statistical analyses see [102] for details.).