Milk consumption leads to prostate cancer

Townsend Letter for Doctors and Patients,  Dec, 2004  by Marjorie Roswell

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I wish more people knew that consuming cow's milk products often results in prostate and other cancers. Yes, many who have had a "Milk is good for you" upbringing will be inclined to argue that point, but I'll make my case here, based primarily on peer-reviewed journal articles. In some instances, the internet will grant full text of these articles, and in others, you can only get as far as an abstract, I have paper copies of most of the full-text articles that I reference below (and many more!) Contact me if you would like a copy.

This column makes extensive use of PubMed, the National Library of Medicine's biomedical literature citation database. Many of the resources described here can be found most easily by entering a PubMed ID number (PMID) at www.pubmed.org. Don't use quotation marks when you enter the PMID. I hope this citation detail proves helpful to you.

First, consider these recent findings:

* Meta-Analysis: "Milk consumption is a risk factor for prostate cancer.... In conclusion, we found a positive association between milk consumption and prostate cancer." Nutr Cancer. 2004;48(T):22-7. [Search Pubmed.org for 15203374.]

* "Among the food items we examined, cheese was most closely correlated with the incidence of testicular cancer at ages 20-39, followed by animal fats and milk.... Concerning prostatic cancer, milk was most closely correlated with its incidence, followed by meat and coffee.... The food that was most closely correlated with the mortality rate of prostatic cancer was milk, followed by coffee, cheese and animal fats." Int J Cancer. 2002 Mar 10;98(2):262-7. [Search Pubmed.org for 11857417.] This isn't exactly new information; for instance, note this 20-year old paper:

* "Suggestive positive associations were also seen between fatal prostate cancer and the consumption of milk, cheese, eggs, and meat. There was an orderly dose-response between each of the four animal products and risk." Am J Epidemiol. 1984 Aug: 120(2):244-50. [Search PubMed.org for 6465122.] Or this one published just two years after that:

* "Positive correlations between foods and cancer mortality rates were particularly strong in the case of meats and milk for breast cancer, milk for prostate and ovarian cancer, and meats for colon cancer." Cancer 1986 Dec 1;58(11):2363-71. [Search Pubmed.org for 3768832.]

I will discuss a number of agents underlying the dairy/cancer connection.

1. Pesticides and Persistent Organic Pollutants (POPs) are carcinogenic, and they bioaccummulate. http://www.panna.org/resources/documents/nowhere ToHide.pdf

I recommend reading PANNA's eye-opening Nowhere to Hide report. Check out Appendix D if you would like to see the actual levels of pesticides found in samples of various foods, including milk, butter, and cheese.

For additional research, search PubMed for words such as "pesticide" or "organochlorine" and "residue" and "milk." If you add the word "human" you'll learn that women are transferring their toxic body burden to their babies via breast-feeding and to their fetuses before birth via the umbilical cord. Consider using the helpful "Related Articles" option. For instance, search Pubmed.org for 10808614, and then click on the "Related Articles" link.

2. Casein. I expect it will surprise people to learn of research pointing to milk protein itself as a carcinogen. Researcher T. Colin Campbell found that he could turn growth of rat liver precancerous lesions on, and then off, and then on, and then off again, based purely on the level of casein (milk protein) in the diet! [Search P.ubmed.org for 1356614 for 1679128 or 1359506.]

3. Radiation. Levels of radiation in milk are currently low, now that it's been 18 years since the Chernobyl accident, but they are likely relatively higher in cows raised near nuclear power plants. The Center for Biological Monitoring at the Davistown Museum has a very rich web page on historic data. The EPA does some testing on radiation levels in milk, but most of the samples are on aggregated milk, which would dilute geographic variation.

http://www.davistownmuseum.org/cbm/Rad6.html

http://www.epa.gov/narel/erams/erdonline.html

4. Estrogen. In the United States, most dairy cows are pregnant, so their milk is rich with female sex hormones, including the cancer-promoting hormone, estrogen. (Unlike humans, pregnant cows continue to produce milk.) Med Hypotheses, 2004;62(1): 133-42. [Search Pubmed.org for 9438850.] Estrogen receptors are found on the prostate gland as well as in breast and ovarian tissue.

5. Insulin-like Growth Factor (IGF-1), and recombinant Bovine Growth Hormone (rBGH, sometimes called BST).

* IGF-1 is a mitogenic hormone found in milk. Cow's milk naturally has IGF-1 in it, but IGF-1 levels increase between 3.6 and more than 10-fold when cows are injected with rBGH. [Search Pubmed.org for 7993454 or 7993421.] or