Industry Response to Bovine Leukemia Virus in Breast Cancer

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Dairy Industry Responds to Bovine Leukemia Virus in Breast Cancer

What was the response to the revelation that as many as 37 percent of breast cancer cases may be attributed to exposure to bovine leukemia virus (BLV), a cancer-causing cow virus found in the milk of nearly every dairy herd in the United States? I discuss this issue in my video Industry Response to Bovine Leukemia Virus in Breast Cancer. The industry pointed out that some women without breast cancer harbored the virus, too. Indeed, BLV was found in the tissues of 29 percent of women who didn’t have breast cancer, a finding the researchers replied “is not surprising considering the long latency period of breast cancer…” In other words, they may not have breast cancer yet.

It can take decades before a breast tumor can be picked up on mammography. So, even though people may be harboring this virus in their breast and feeling perfectly fine, the cancer may still be on its way. That’s how other cancer-causing deltaretroviruses appear to work. These viruses can make proteins that interfere with our DNA repair mechanisms. Infected cells are then more susceptible to carcinogens and slowly accumulate mutations over time. “Therefore, evidence of BLV in normal breast tissues prior to premalignant and malignant changes would be expected.” This pattern is what we see with cervical cancer, “in which the causative virus (HPV) is found not only in the malignant [cancerous] tissue, but also in premalignant dysplastic areas [the precancerous tissue] and in normal tissue adjacent to the malignant tumor.”

If BLV, a retrovirus, is really causing thousands of cases of breast cancer every year, wouldn’t some of the anti-retroviral therapies like some of the AIDS drugs be able to counter it? Perhaps, but it’s best not to get infected in the first place.

However, the agriculture industry appeared to be more concerned about consumer confidence in U.S. dairy than consumer cancer. Indeed, the “U.S. dairy industry face[d] a brewing public-relations brouhaha,” and it became “concerned about the possibility of eventual mandatory control of these diseases in dairy cattle along with public perception and an impact on the consumption of dairy products.” What would control look like? BLV is a blood-borne virus, but how is it spread? Is Bessie sharing dirty needles? In a sense, yes: “[B]lood (and BLV virus) is readily spread from animal to animal with blood contaminated needles and/or syringes, obstetrical sleeves, saw or gouge dehorners, tattoo pliers, ear taggers, hoof knives, nose tongs,” and other instruments that aren’t disinfected between animals. So, for example, when farmers are gouging or sawing at the cows’ heads during dehorning, “they are likely to drive blood into the next animal during the subsequent dehorning process.” Or, when they’re sticking their arms into cows’ rectums for artificial insemination, it’s not uncommon for there to be rectal bleeding—then they just go from one cow to the next.

More than 20 countries have successfully eradicated BLV from their herds by changing their practices, whereas it remains an epidemic in the United States in part because we’re not cleaning and disinfecting blood-contaminated equipment for things like “supernumerary teat removal,” which is done because “the presence of extra teats detracts from the beauty of the cow.” Supernumerary teats are removed by pulling them from the udder and cutting them off with a pair of scissors. Those scissors had better be clean—otherwise they could spread BLV from calf to calf and ultimately to someone’s breakfast, lunch, or dinner. Of course, we could just not slice off their teats at all, but then how would we “improve udder appearance?”

Up to 37 percent of breast cancer cases are attributable to exposure to bovine leukemia virus? See my video The Role of Bovine Leukemia Virus in Breast Cancer and its prequel, Is Bovine Leukemia Virus in Milk Infectious?.

The meat and dairy industries’ intransigence in the face of a human health threat reminds me of the antibiotics and steroids issues—continuing to place the public at risk to save a few bucks. See, for example, Antibiotics: Agribusinesses’ Pound of Flesh and Zeranol Use in Meat and Breast Cancer.

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

86 responses to “Dairy Industry Responds to Bovine Leukemia Virus in Breast Cancer

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  1. This is concerning but it begs the question: why aren’t breast cancer rates in men higher (they are less than one percent) since they too consume dairy products?

    1. Perhaps it’s because men have a different endocrine make than women? Men metabolize food differently than women, so wouldn’t this play a role?

  2. These numbers don’t add up for me. About 1 in 8 women will develop invasive breast cancer in her lifetime; that’s about 12%. If the BLV virus causes or contributes to about 37% of them, that is about 4.4% of women in her lifetime. Yet BLV is found in about 29% of women without breast cancer — a much higher percentage than will ever develop breast cancer, much less a breast cancer attributable to BLV. Actually, these numbers are close enough to suggest that about 1/3 of women are infected with BLV, whether or not they develop breast cancer. I don’t know what the error bars look like, I don’t know the sample size, the ages of the women tested, how many die with BLV infections who don’t developed breast cancer, etc. I have too little information.

    That’s not to say that BLV is not involved in the development of some breast cancer, but this data alone does not convince me.

    1. Dr.J, nothing in medicine is ever 100%. It just seems that the data is pointing to the presence of BLV increasing the risk of someone developing breast cancer, though not to a 100% chance. Are you also not convinced that smoking cigarettes increases one’s risk of developing lung cancer? Only 9.5% of women who currently smoke develop lung cancer. Here are the other stats about lung cancer for comparison, so you can get a better perspective of carcinogens and cancer risk:

    2. If this is something like an epidemic, spreading through US dairy herds, then the numbers of breast cancer victims down the road will be much higher. Current numbers might not be representative. why would anyone take this chance, when there are so many other reasons not to eat dairy?

      1. As already stated above, Dr.Greger is correct. Cows are not humans, their anatomy is slightly different. They have to go through the rectum to access the cervix:
        “Although not part of the female genital tract, the rectum (terminal portion of the large intestine) is an important organ for you to become familiar with because your arm inside the cow will be working through this thin-walled tube. The rectum is 10 to 12 inches long and very stretchable. That is important because it is through the rectum that you will manipulate the cervix.

        The anus serves as a valve between the rectum and the outside. It is made up of a circular (purse string) muscle located directly under the skin. It surrounds the very end of the rectum. Again, the anus is stretchable, hence, your hand and arm can easily slip into the rectum. Circular muscle contractions move along the rectal wall toward the outside. When strong, these contractions may block your hand from moving forward and make it difficult to manipulate the genital organs through the rectal wall.”

    1. Grant, yes the pipette is routed through the vagina to the cervix, but the gloved hand goes via the rectum to ‘scoop up’ so to speak, the uterus of the cow, felt through the intestinal wall. :)
      Just sayin’

    2. In that you would be wrong. Search for bovine Insemination images and you will see men with long gloves up to their shoulder in the rectum.

    3. The farmer sticks his/her arm up the cow’s rectum and to grab the cervix, which is reachable via the rectal wall, and get it into position. The probe with the semen goes into the vagina. With one hand holding the cervix in position, the other hand injects the semen. Dr. Greger has reported the process correctly. There is NO disinfection of either hand. This is from someone who has artificially inseminated cows. There are plenty of YouTube videos on the process too, if you are interested.

    4. Grant and others, recto-vaginal artificial insemination is achieved by inserting the semen into the vagina and then guiding into the cervix by means of a gloved hand in the rectum.

      1. Cookie and L,

        Please read Bev’s description of the procedure.

        And to confirm see the Oklahoma State University instructions for the procedure….. very clear you use two hands: “The inseminator places his hand in the rectum and manipulates the reproductive tract so that the gun passes through the vagina, then it is manipulated through the cervical rings, and then held at the internal opening of the cervix for semen deposition.”

        As to the anatomy see this article for a complete breakdown of the parts and placement:

        Dr. Greger’s info is on the mark…..and verifiable.

        Dr. Alan Kadish moderator for Dr. Greger

    5. Why not investigate the process first? The technicians arm goes in the cows rectum to control the sperm placement from the tube inserted in the vagina.

  3. I’m a little confused about something from the article. I’m not perfectly familiar with a cows anatomy, but artificial insemination wouldn’t take place in a cows rectum. That’s where the cows poop is passed. Artificial insemination takes place in a cows vagina.

  4. The fact that 20 countries have successfully eradicated BLV from their herds and it is still an epidemic in the US is one of those telling sentences.

    So is the concept of trying to improve udder appearance.

    Selfish, shallow and greedy is as selfish, shallow and greedy does.

    1. I wonder if the rate of breast cancer decreased in those countries which have eradicated BLV infections? Or is it too soon to tell?

      I also wonder if BLV infection in breast cancer tissues has any effect on mortality from breast cancer: do these rates go up or down relative to those breast cancers without BLV infection? Does it affect survival time? Age at mortality? All cause mortality?

    2. This part the good doc has wrong. Improving udder appearance may be the excuse that is given, but the real reason is that an udder with extra teats doesn’t fit the milking machine.

  5. So does this open the door for women with breast cancer to sue the dairy industry? Or families that have lost mothers, sisters or daughters? It would be a difficult argument to prove cause. But a jury would clearly see the presence of BLV in women’s tissue is clearly negligence on the industries part. Especially when 20 other countries have erradicated BLV from their herds. Johnson and Johnson has over 1,000 lawsuits pending for the opioid crisis. Monsanto has over a billion in awards to victims with non-Hodgkin lymphoma.

    1. Gregory.

      It does prove negligence.

      And, yes, industries are being held accountable for these types of things.

      Those of us who can’t sleep at night get to see a lot of industry lawsuit commercials.

      Talcum powder and ovarian cancer is another one.

      1. Negligence is usually considered to be the result of carelessness. This on the other hand appears to be a deliberate policy decision made on financial grounds?

  6. Wretched corporate savages that permit this torrture of animals for profit. And wretched Americans that permit it to go on without protest and without the slightest desire to sacrifice their barbaric and miserable cultural practices. They deserve the bad karma they are sowing.

      1. That ad was found to be misleading and unethical by the California board. Changed to “milk has something for everybody” namely cancer, diarrhea or constipation, osteoporosis, lung infections etc.

      1. “The real struggle in being vegan doesn’t involve food. The hardest part about being vegan is coming face-to-face with the darker side of humanity and trying to remain hopeful. It’s trying to understand why otherwise good and caring people continue to participate in needless violence against animals – just for the sake of their own pleasure or convenience.” -Jo Tyler

      1. “The first thing you notice when you go vegan is that everyone is mad, and they tell you you’re mad. You voluntarily enter the moral Twilight Zone. You discover a grotesque inconsistency between the beliefs people express and their behavior. You realize that we’re all highly irrational, and that it’s emotion that rules culture, and culture rules the behavior of individuals. No matter how much harm it causes, nothing we do needs to be justified as long as it’s popular enough.” – Karen Manfrede

    1. “In their behavior toward creatures, all men are Nazis. Human beings see oppression vividly when they’re the victims. Otherwise they victimize blindly and without a thought.” ― Isaac Bashevis Singer

    1. The 51 tumour samples and 19 adjacent normal tissue samples used came from the USA, Mexico and Vietnam.

      It’s not clear to me how many of the tumour samples came from the US but about half of the total number seem to be from the US..

      Therefore, we are talking about a relatively number. There is consequently the possibility that the Law of Small Numbers may be applicable here eg
      ‘the tendency for an initial segment of data to show some bias that drops out later’

      Or it could be an issue related to the test processes used in the various studies. That requires further consideration research. Regarding this point, the article also notes
      ‘Although no paired-read corresponding to five different BLV variants could be identified, the possibility remains that extensive sequence variability impaired detection’

      Either way, this study shows no trace of BLV but two other studies do suggest transmission to humans. The question remains open but the prudent course would still be to avoid dairy.

        1. When you look at other studies where there have been BLV found, some locations have a lot and some have a little.

          The study had Vietnam, Mexico and some from USA, but it was a small group and it is possible that parts of the USA have cleaned up their processes.

          In Peru and Paraguay, 42.3 % (139/328) and over 50 % (76/139) of samples, respectively, were BLV positive. In Bolivia, the BLV infection rate was up to 30 % (156/507) at the individual level. In Argentina, 325/420 samples were BLV positive, with a BLV prevalence of 77.4 % at the individual level and up to 90.9 % at herd level. By contrast, relatively few BLV positive samples were detected in Chile, with a maximum of 29.1 % BLV infection at the individual level.

          Okay, so Argentina has a high level of BLV.

          Does it have a high level of Breast Cancer?

          Yes, it does.

          That is anecdotal, but it should match.

          So, does Chile have high or low rates?

          Chile has lower breast cancer incidence rates compared to those in developed countries.

          1. They said this strange sentence about Mexico

            BLV is also present in both beef and dairy cattle in Mexico [119]; however, disease is either absent or limited to specific areas [17] (accessed on 22 Dec 2016).

            The disease was not confirmed is what an official report said about Bovine Leukemia Virus in Vietnam.

            So, 2 out of 3 of the locations may not have had it to begin with?

            1. I looked up the USA and there are differences from state to state.

              The small number of herds in some states (only 7 herds total in Texas, Utah, and Idaho combined) may have resulted in insufficient power to detect significant pairwise comparisons.

              I don’t know if that 7 herds means they didn’t test the herds in a place as big as Texas, but Texas, for being as big as it is has one of the lower rates of breast cancer in the USA.

              Again, none of this is proof of anything.

              But it tells me that they weren’t going to find it in many of the samples in 2 out of 3 of the countries to begin with.

              1. US does not require testing. “Cost” is the justification. In addition BLV takes years to develop at detection level, US cows are short lived with massive emphasis on production, not quality of life. Typical lifespan is less than 5 years. Do we want to see real data?

    2. I found several articles published in reputable journal stating opposite finding from this one.

      I looked at who funded the study you mentioned and a livestock company was listed there. I don’t think that’s fair and totally unbiased despite their disclaimer.

      If anything, more research is needed and I would advise my patients to not take this risk and decrease or consider totally removing their consumption of any dairy products. There is no reason we should be consuming the breast milk of another species anyway.

  7. “Whoever is content with the world, and who profits from its lack of justice, does not want to change it.” -Friedrich Durrenmatt

    “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” – Upton Sinclair

    “Livestock farmers, no matter what kind — from the largest, most cynical, and inhumane factory farm­ers to the smallest, seemingly most ethical pasture-based farmers — traffic in death. It is death that is our aim, our purpose. Death is the end. Life is the means. Money the reward.”- Bob Comis, former pig farmer

    1. ahimsa42,

      When I watched PlantPure Nation, what struck me was how very willing the small farmers were to switch from livestock.

      They just needed a system.

  8. Well, the good news is that plant milk is already changing the whole landscape of the milk industry.

    Some dairy farms already switched to selling plant milk.

  9. “Or, when they’re sticking their arms into cows’ rectums for artificial insemination, it’s not uncommon for there to be rectal bleeding—then they just go from one cow to the next.“. Really? I think all mammals get pregnant the same way and it’s not through their rectum. Correct this please.

    1. If we read beyond the headline, we find that the study showed that so-called vegans and vegetarians had LOWER risk of adverse events ,,,, 7 fewer adverse events per thousand people over a ten year period …… comoared to meat eaters. Non meat eaters had 10 fewer cases of heart disease but 3 more cases of stroke for a net reduction of 7 cases.

      In other words, the study showed that non meat eaters have a lower risk … but the BBC chose to run a headline that suggests that non meater eaters have higher risk.

    2. Atherosclerosis, hardening of the arteries with cholesterol plaques, which calcify and harden over time, can occur in vegetarians and vegans from the larger amount of nut oils they are ingesting.

  10. How do I find out if my breast caner was a result of this virus. I am a lacto oval vegetarian, meaning I eat diary and eggs. Is
    there a test that shows if you have the virus.

  11. From the article above: “Or, when they’re sticking their arms into cows’ rectums for artificial insemination, it’s not uncommon for there to be rectal bleeding—then they just go from one cow to the next.” I have a hard time believing that artificial insemination can be accomplished via the rectum. Perhaps the author meant vagina, as in “sticking their arms into cows’ vaginas” and “not uncommon for there to be vaginal bleeding.” Come on, now!

    1. Debbie, please read previous comments. Artificial insemination in cows and other similar animals involves a farmer sticking one arm in the cow’s rectum.

  12. It doesn’t appear anyone in these comments has read anything regarding 1. what exactly retroviruses are and 2. The false narrative around them and their ability to cause anaplasia. DNA virus (herpes, chicken pox, measles, HPV), could not provide even a remote chance of causing cancer. Why? Cancer would be contagious (it is not) but regardless it would not be able to co-opt cells since the virus would kill them first. RNA virus, (“Polio”, “AIDS”,) – in quotes because neither were ever proven to be caused by a retrovirus – these RNA virus are long known in science as associated or passenger virus, 1,000’s of time smaller than DNA virus and do not kill the cell. There are millions in our bodies and none of them are distinguishable from any other….(unless discovered by Robert Gallo). We know now through the dedicated and irreproachable work of Duesberg, that cancer is not gene mutation but aneuploidy, or chromosomal chaos. And if this Bovine retrovirus is being “isolated” by PCR, which can find minute DNA fragments of past virus, bacteria infection and other cellular debris, that are relics and not by any means whole endogenous DNA viral particles that would prove causation….then all this is much a-do about nothing. Retroviruses as catalyst for cancer was settled long ago in Nixons Virus-Cancer Program. They don’t. Once Kochs Postulates was thrown overboard during the Polio circus, all manner of blame and trickery surfaced as 100’s of thousands of virus hunters emerged from universities around the U.S., all of them looking for a virus to blame a disease on.

  13. I find it interesting that a virus that causes leukemia and lymphomas in cows, sheep and goats, can cause breast tumors in people. Disease causation doesn’t work like that. Because you have antibodies to a virus, doesn’t mean that you have the condition (leukemia /lymphoma) caused by the virus in other species. Some vaccines use killed organisms, or pieces of them, to produce protective antibodies. I can have polio antibodies, but not have the disease, polio. Cowpox is used to vaccinate people against smallpox, because the antibodies from cowpox cross react with smallpox, and inactivate the smallpox virus. While you can still get a short-lived pox lesion and subsequent mark when given the vaccine, you don’t get liver, brain, breast or skin cancer. So the presence of a tumor or cancer is not necessarily related to the presence antibodies. Otherwise, some lawyer would be suing vaccine companies for every tumor that shows up because we have antibodies to those diseases we were vaccinated against. GET VACCINATED ANYWAY – IT PREVENTS STUPIDITY FROM REIGNING SUPREME.

    So, getting back to Bovine Leukemia Virus (BLV) and breast cancer. If BLV is the culprit in such a high percentage of breast cancers, is it coming from milk from contaminated cows? Do all of the women with breast cancer that are positive for BLV drink raw, unpasteurized milk from cows, goats or sheep? Because BLV is inactivated (killed) by High Temperature / Short Time (HT/ST) pasteurization. It’s one of the methods used to prevent the spread of BLV in calves. And calves are negative for the virus if only given pasteurized milk.

    It seems to me that this is more pseudoscience (fake news) used to sensationalize the topic and grab headlines. The adage, “Don’t believe anything you hear and only 50% of what you read,” applies. Now educate yourself so you know what 50% to believe.

  14. I am still thinking about the study with the stroke in England.

    The vegetarian group was high dairy and salt and oil and low in B12.

    I understand that they had twice the level of Alzheimer’s and I really want to know if it went down when they lowered their heart-attack rates.

    They stayed low in B12.

    Did they lower heart attack risk and maybe still keep Homocysteine high and not help their Alzheimer’s rates?

    The BBC didn’t say “stroke” and “Alzheimer’s” and Dr. Greger mentioned that the Alzheimer’s used to be not in the Top 10, but now it is number 2.

    The vegetarian group used to have twice the Alzheimer’s. The country is still going up in it. The BBC didn’t rub it in their faces. Heart issues and Ischemic stroke dropped in the vegetarian group.

    This to me could be a preview of Dr. Ornish’s coming attractions. Except for the dairy and salt and the fact they stayed low in B12, but maybe raised their potassium intake????

    If I could only find the data.

  15. I have resorted to writing to some of the people who interview Dr. Greger to ask them these questions and to mention that I am searching to see if someone interviews him about it.


    Yes, this is how the non-bloggers think they can get things done.

    1. Finland improved by lowering saturated fats. They stayed high in fats.

      But there is enough of an improvement in the diet in the vegetarian group to lower heart problems.

      I am wondering if there is a portion of these people in the vegan community who have converted to Whole Food Plant-Based group, which has become part of the study.

      It seems like it would be the vegans who heard the message.

      The other factor that I see is that half the country had switched to olive oil about when the bad news of the shocking study came out. Some are probably coming off of oil and some have switched to coconut oil.

      I don’t know if there are any surveys of the vegan community with regards to what do they eat.

      Some would be anorexic.

      Seems like every vegan event there should be a survey about that.

      1. I am thinking that if half the country switched to olive oil – based on the Mediterranean diet – but most of them kept eating meat and the vegetarians kept eating eggs and cheese. Would that be when the vegans started having an improvement in things just from the oil change?

        1. I also missed the part in the old video where you should have been talking about the Hemorrhagic stroke levels back then.


          I am guessing you weren’t trying to make the zero benefit from going vegan and twice the Alzheimer’s sound better by leaving out the most deadly form of stroke.

          When I was trying to stumble through the data, I think the ischemic stroke used to eclipse the hemorrhagic stroke or that is my guess. They got better at the most common kind of stroke.

          Did they get worse at Hemorrhagic or are they just stubborn about not supplementing B-12 and D3 and Omega 3 or something?

    1. Okay, back to the BBC.

      They didn’t mention double the Alzheimer’s rate and Alzheimer’s went from not in the Top 10 to #2 and is still going up.

      If they just wanted to give veganism a black eye, double the rate of Alzheimer’s would have been a good one.

      I think the Alzheimer’s rate must not any longer be the veggie group’s even bigger Achilles Heel.

      Did they go from double the rates to the same rates?

      Has England ever done a Homocysteine study with vegans?

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