Breast Cancer, Beef and Milk: You Need to Know This

A study published this month by researchers at the University of California, Berkley found that women exposed to bovine leukemia virus which is found in milk products and beef, are three times more likely to develop breast cancer. The study is titled “Exposure to Bovine Leukemia Virus Is Associated with Breast Cancer: A Case-Control Study.”

Bovine leukemia virus (BLV) is carried by most cows. Only about 5% of cows get sick from the virus, so many cows with BLV continue through their normal lifespan with no signs or symptoms.

“Approximately 38% of beef herds, 84% of dairy herds, and 100% of large-scale dairy operation herds in the USA are infected with BLV.” The Department of Agriculture found in 2007 that 100% of milk tanks from dairies with over 500 cows had bovine leukemia virus in the milk.


Cooking and pasteurization are supposed to kill viruses such as BLV. However, consuming raw milk, milk that was not adequately pasteurized, or under-cooked burgers and steaks means the virus is still present.

It was initially believed that BLV could not be transmitted to humans. Studies were done in the 1970’s that said there was no risk to humans from BLV. Medicine has much more sensitive tests today that are able to detect the presence of viruses and other pathogens in human tissue, and these tests have now located the DNA from BLV in the human body.

The Virus Cancer Connection

We already know that viruses can cause cancer. For example, HPV (human papilloma virus) causes cervical cancer, and hepatitis B virus causes liver cancer.

Previous studies have also established that BLV is found in the human body, and that this virus prefers to localize in breast tissue. “BLV DNA and protein were present in some humans, and were localized primarily to mammary epithelium, the cell type from which most breast malignancies arise.”shutterstock_283185584

The research into BLV and breast cancer is only in its beginning stages; there is not proof that bovine leukemia virus, or the body’s reaction to BLV, causes breast cancer. At the same time, according to a lead researcher, the correlation between BLV and breast tumors is remarkable.

“This odds ratio is higher than any of the frequently publicized risk factors for breast cancer, such as obesity, alcohol consumption and use of post-menopausal hormones.” Studies are currently being completed to better understand the connection.

So What Now?

Many things can affect a woman’s risk of developing breast cancer. For example, we know that being overweight, consuming hormones and drinking alcohol are risk factors. Now we also know there is a correlation between BLV and breast cancer, and that BLV gravitates towards cells in the breast that are known to transform into malignant tumors.

We have been educated since childhood to look toward dairy products for calcium. However, there are many excellent sources of calcium that do not come from dairy products.

Mammals throughout the world only drink their mother’s milk for a few months at the beginning of life, and yet go on to develop strong bones from their regular diets. Humans are designed to grow strong bones from healthy foods too. Numerous foods provide calcium to humans the natural way:

White Beans
Bok Choyshutterstock_243020068
Black Eyed Peas
Soy and Tofu
Turnip Greens

In other words, all of those plant based healthy foods we are supposed to be eating anyway are a great source of calcium and all the protein needed.

I will follow the research on this topic as it is published and share updates.

You can read the entire Berkley study for yourself here

The information contained on this site is for educational purposes only and should not be used as a substitute for diagnosis or treatment rendered by a licensed medical professional. It is essential that you discuss with your primary care provider any symptoms or medical problems that you may be experiencing.


Buehring GC, Shen HM, Jensen HM, Choi KY, Sun D, Nuovo G. Bovine leukemia virus DNA in human breast tissue. Emerg Infect Dis 2014;20:772–782

Buehring GC, Shen HM, Jensen HM, Jin, D, Hudes, M, Block, G. (2015) Exposure to Bovine Leukemia Virus Is Associated with Breast Cancer: A Case-Control Study. PLoS One. 2015; 10(9): e0134304.

APHIS, Veterinary Service, Center for Epidemiology and Animal Health, USDA. Bovine leukosis virus (BLV) in U.S. beef cattle. Information Sheet, Feb 1999.

APHIS, Bovine leukosis virus (BLV) on U.S. Dairy Operations, 2007. Oct. 2008; available on National Animal Health Monitoring System. High prevalence of BLV in US dairy herds. Accessed August 1, 2010.


  1. So…I was recently diagnosed with breast cancer and had a double mastectomy with a rebuild. Still waiting to start chemo from slow healing. So….big question I drink milk daily do I need to stop????


    • Dear Julie
      I’m so sorry to hear about your diagnosis and I wish you the very best with your chemo and recovery. SeeTheNP does not provide any medical advice. We only provide education about research findings specific to both illness and wellness. Please talk to your licensed medical care provider about best dietary choices now and throughout treatment. A link to the study was provided at the end of the article. Feel free to share that with your care providers, and always follow their guidance. We wish you the very best for a speedy recovery. ❤


  2. […] The body’s own immune system will also fight the virus. For most viral infections this usually takes 7-10 days. However, there are many viruses the body can’t get rid of on its own. These include the human immunodeficiency virus (HIV) and hepatitis viruses. Some viruses also lead to cancer. […]


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