Is Bovine Leukemia Virus in Milk Infectious?

Is Bovine Leukemia Virus in Milk Infectious?

“Is Bovine Leukemia Virus
in Milk Infectious?” Decades ago concern was raised that the milk of dairy cows frequently contained a
leukemia-causing virus, but they were talking
about bovine leukemia, the leading cancer killer
among dairy cattle. Most U.S. dairy herds are infected
with the bovine leukemia virus, thus the question of whether
they’re releasing infectious virus into milk is an important
public health consideration, so researchers at U. Penn decided
to put it to the test, and indeed infectious virus
was demonstrated in the milk of 17 of the 24 cows tested, indicating that
humans are often exposed orally to bovine
leukemia virus. But just because
we’re exposed doesn’t mean it’s causing
human disease. How do we even know BLV
can even infect human cells? We didn’t until 1976
when it was discovered that bovine leukemia virus
can indeed infect human, chimpanzee, and monkey cells. OK, but that still doesn’t mean
it necessarily causes cancer in other
species, though. You can’t lock human infants in a
cage and feed them infected milk but you can infant chimpanzees. And chimps Bois and Roger,
fed the infected milk, developed leukemia and died…. We didn’t even know chimps
could get leukemia. The fact that BLV-infected milk
appeared to transmit or induce leukemia in our closest
living relatives certainly did raise the stakes, or at least impugn the
safety of steaks… But human beings are
not chimpanzees. Yes, our DNA may
be 98% identical, but we may share 60% of our
DNA with the banana. We need human studies. Thanks to the pesky
Nuremberg principles we can’t do interventional trials, but what about
observational studies? Do cattle ranchers have
higher rates of cancer, for example? Apparently so. Leading some to suggest that
milk and egg-borne viruses may be important in
the development of human leukemias
and lymphomas. But farmers may be exposed to all sorts of potential
carcinogens such as pesticides. It’s like, YES, large animal vets
have more leukemia and lymphoma, but some were also
particularly lax in the use of x-ray
protective equipment. So, it didn’t necessarily have
anything to do with animal viruses. What we needed were so-called
serology studies, testing people’s blood for
antibodies against the virus, which would prove
human exposure… and we got ‘em. Ten different studies looking
for BVL antibodies in cancer patients and
non-cancer patients, creamery employees
vs. office employees, veterinarians, unpasteurized
milk drinkers, the whole gamut and not a single study
found a single individual with antibodies to BLV. So 1981, case closed;
strong evidence BLV is not transmissible
to people. But the strength
of the evidence is only as good as the
strength of the test. Bois and Roger didn’t develop
detectable antibodies either… and they died from it. The tests back then were
just really not sensitive. Clearly the question of whether
bovine leukemia virus poses a public health hazard
deserves a more thorough investigation using highly sensitive
molecular probes. It would take a few
decades but here it is, a landmark study that
we’ll cover, next.

41 thoughts on “Is Bovine Leukemia Virus in Milk Infectious?”

  1. Only with Dr. Gregor do you refer to a mostly dry reading of peer reviewed medical literature as ending on a "cliffhanger"

    Well done sir, well done.

  2. I think BLV is found in those farmers, but along the lines of thinking that so far other animal leukemia viruses such as dog and cat; as you've previously published. Do they play a protective or harmful role?!  😛  or is there a further twist…

  3. We all have to be thankful for Dr. Michael Greger fit it's videos. It's by far the most trustworthy way to get the best information that can save your lives 😷🤒🤕😍😘

  4. leite é veneno não tomem não tem calcio vaca tira calcio do capim commam verduras não tomem veneno

  5. Fantastic info. The case keeps building against milk. About 15 years ago in 8th grade, I was discussing the negative health effects of milk and people were laughing at me. Always found the stuff gross

  6. Agh, always with the cliff-hangers!
    Anyway, I'm just releasing some frustration.
    I love these videos! Super informative and evidence based. Thank you Dr. Greger, staff and volunteers of

  7. I saw the next episode at a sneak preview…. turns out Buck Rogers jumped out of the rocket a second before the crash!

  8. I'd like to hear Dr. Greger's take on the CrossFit war on sugar. Their many facebook pages and posts are a goldmine of shady study references and anecdotal citations.

  9. Wow. Your team really sets the standard for medical information presentation in investigative reporting. Great work. Thank you.

  10. As Jim Morris once said, "Milk is for babies… Baby calves. We are the only species on the planet, that consumes another species milk." Next thing we'll be consuming rat milk, cat milk, or dog milk. Yummy? Not quite…

  11. Reason 1,001 to give up dairy. Reading the China Study was enough for me. Then, learning how cruel the dairy industry is….never, ever touch the stuff. Non-dairy, vegan…nothing lost, all gain.

  12. Just heard about this supposed "virus" for the first time today.
    Been consuming healthy, wholesome milk and milk products in copious amounts since birth, and now I'm 50 years old.
    I don't have Leukemia yet, though….
    Just wondering exactly how long this supposed "virus" takes to work: Is it 51 years? Is it 100 years?
    Either way, I'm not too worried, and I will continue consuming healthy, wholesome milk and milk products, because the lacto-vegetarian diet is superior.

  13. Aaand new studies : "Bovine leukemia virus discovered in human blood"

    " Thus, BLV has the potential to be an
    important initiator of cancer in human tissues, and the
    data reported here further strengthen the evidence that
    BLV infected cattle pose a likely risk to humans"

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