The Vegan Post

by William Harris, M.D.

Cancer is not caused by bacteria, faulty diet, inadequate exercise, environmental contaminants, ionizing radiation, tobacco, viruses, nor heredity. Cancer is caused by a series of genetic mutations in DNA which may be either germline (inherited) or somatic (acquired during life). However, the chances of these mutations occurring in sufficient number to result in cancer is affected by all of the preceding factors.

DNA is the critical target molecule in carcinogenesis (1). Although DNA has various repair mechanisms, some types of damage persist and become the basis of the defective molecular biology that is cancer. Oncogenes (tumor genes), tumor suppressing genes, and aptotic genes (causing programmed cell death) normally interact to build normal cells, to prevent excessive growth, and finally to kill the cell before genetic mutations cause it to malfunction.

Table 1. U.S. cancer rates.

Cancer is the second most common cause of death in the United States, where over 1.3 million new cases of cancer are diagnosed annually, with 550,000 deaths. Current United States incidence figures for the ten leading types of cancer are shown (2). Women have an approximately 1:8 lifetime chance of developing breast cancer, and men have an approximately 1:5 chance of developing prostate cancer. Rates above are per 100,000 in 1992. Both Hodgkin’s disease and non-Hodgkin’s lymphoma are included under lymphoma.

There are three categories of evidence suggesting that a veg*n (vegetarian or vegan) diet reduces risk for various types of cancer.

Epidemiologically, the intake of animal source food correlates with the country-by-country incidence of six types of cancer. Although none of the reporting countries can be assumed to have large vegan or even vegetarian populations, it appears that the less animal source food per capita, the lower the cancer rate.

In the graphs below, the Y axis contains the disease, the X axis contains the animal source dietary risk factor. R is the correlation coefficient which reflects the “goodness of fit” of the data points to the sloping regression line. The p-value is the probability the apparent relationship is merely a mathematical coincidence. An R of 1 would indicate a direct linear relationship, while an R of zero would indicate no relationship. A p-value of .05 indicates a 5% chance of mathematical coincidence but numbers less than .05 are traditionally taken to suggest a non-coincidental relationship.

A. Breast Cancer

The etiology of breast cancer, as with most cancer, is multi-factorial, with a strong hereditary component. Using BMDP (3) statistical software, I performed multiple regression analysis on breast cancer incidence(4) country by country using Food and Agriculture Organization food consumption data (5) for animal source calcium, animal Calories, animal fat, animal protein, butter and ghee, cheese, eggs, milk production (metric tons/yr), plant source calcium, plant fat, plant protein, plant Calories, total calcium, total fat, total Calories, and total protein.

I included additional vital statistics from The Book of World Rankings (6,7) for birth rate, female life expectancy, GNP/caput($), infant mortality, male life expectancy, male/female cancer ratios, meat consumption (kg/caput/yr early 70′s), sugar consumption (kg/caput/yr -1976), and total population.

Of these (sometimes not independent) variables, the highest correlation ( R=.76, p<.001) with breast cancer incidence was from animal source Calories, (with animal fat and the other animal constituents close behind). » Read the rest of this entry …