Cancer and the Vegetarian Diet - A. Breast Cancer
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From William Harris, M.D.
December 21, 1999

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).


Plant protein consumption had a moderate negative (protective) correlation (R= -.36, p=.046).


Of the other positive correlations, animal source calcium had an R value of .62 and p=.0026. This would support the contention that dairy hormones are a risk for human breast cancer (8). Insulin-like growth factor (ISGF-1), present in both cow milk and human milk is known to stimulate the growth of human breast cancer cells (9, 10).

The vegetarian diet has been shown to lower the level of estradiol (11) (an estrogen) and raise sex hormone binding globulin (SHBG) levels (12). Some forms of breast cancer are estrogen-receptor (ER) sensitive and the phytoestrogens from plant foods (13, 14), particularly soy products, are thought to block ERs in a manner similar to tamoxifen. Lower post-treatment ER-rich breast cancer survival rates in women who reported higher dietary fat intake have been found.(15)

Although the most recent pooled-analysis of fat intake as a risk factor for breast cancer produced negative results (16), a case-control study (17) conducted in Italy on 2,569 incident cases of breast cancer and 2,588 controls found an odds ratio (OR) of 1.22 for saturated fat, and 0.89 for unsaturated fat.

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We began this archive as a means of assisting our visitors in answering many of their health and diet questions, and in encouraging them to take a pro-active part in their own health. We believe the articles and information contained herein are true, but are not presenting them as advice. We, personally, have found that a whole food vegan diet has helped our own health, and simply wish to share with others the things we have found. Each of us must make our own decisions, for it's our own body. If you have a health problem, see your own physician.