Exposure to bovine leukemia virus in meat and milk (or blood transfusions from those who eat meat or milk) is a risk factor for cancer.
In 2015, researchers in California found the bovine leukemia virus (BLV) integrated into the DNA of human breast cancer tumors from mastectomies. This virus was found in much higher numbers than normal breast tissue obtained from breast reduction surgery. Based on this difference, they calculated that about 37% of breast cancer cases could be caused by exposure to BLV, perhaps by consuming milk or meat from infected animals.
In response, the dairy and meat industries seemed more concerned about consumer confidence than consumer cancer. But scientifically, the focus of the research turned to the question: Can the California results be replicated? The answer, it turns out, is yes. They are more common among Iranian women. Repeated in Brazil. In Australia, the link was even stronger. In Texas, they found the same thing. Women diagnosed with breast cancer were found to be more likely to have bovine leukemia virus DNA in their breast tissue compared to women without cancer, such that the cancer risk was calculated at 51.82%, indicating that this meat and milk virus may be responsible for at least half of the breast cancer cases among the Texas women they studied.
In all, six of the eight studies conducted so far detected the virus in human breast tissue, “strongly suggesting that BLV infects humans, and that breasts are potential targets for infection.” Four of the five studies that compared infection rates in cancer versus normal breast tissue found that the likelihood of finding the virus in tumors was, on average, four times higher. How does that compare to other breast cancer risk factors? If you take hormone replacement for five years, you can increase your risk of breast cancer by 30%. If you take birth control pills for more than twelve years, your risk may increase by 40%. If you are obese in adulthood, your risk can increase by 60%. Having a first-degree relative with breast cancer may double your risk. But having your udder infected with the bovine leukemia virus can quadruple your risk, as you can see below and at 2:16 in my video. Breast Cancer and Bovine Leukemia Virus in Meat and Milk.The only things more dangerous than BLV infection were the mutation of the BRCA gene, like Angelina Jolie, or a high dose of ionizing radiation, like living in the wrong place at the wrong time, like Hiroshima and Nagasaki during World War II.
Without confirmation, other studies suggested that elderly patients were more likely to test positive for bovine leukemia virus. That makes sense if BLV is from exposure to milk and meat. The older we get, the more food we’ve had—and the more chance of infection over time. The researchers also found that the virus comes first, before the diagnosis of cancer; they found that it was present in some breast tissue 3 to 10 years before the cancer was diagnosed. “This contradicts the idea of the virus attacking cells that are already malignant,” dismissing the idea that perhaps the virus somehow becomes attracted to cancer after the fact. Could this explain the consistent findings that breast cancer tissue is more likely to harbor infection? Again, the data showed no – the virus appeared to come first. Although the review does not provide conclusive evidence that BLV is a cause of breast cancer, based on the best available balance of evidence, BLV infection appears to be a risk factor for breast cancer.
The latest revelation is that BLV has now been found in human blood, too. This has a number of potential consequences. For example, blood banks do not test you. Therefore, it is possible that you can get it from eating meat or milk, and from receiving blood from someone who has eaten meat or milk. This could also mean that BLV can cause leukemia in humans. It’s done by chimpanzees. Two newborn baboons were fed milk from naturally BLV-infected cows, and both died of leukemia. We didn’t even know chimpanzees could get leukemia. This certainly suggests the possibility of transmission or induction of leukemia by ingesting milk from cows infected with BLV, or blood circulation can carry the virus to other organs. In cows, this virus causes blood cancer, but this is because dairy cows are slaughtered and turned into burgers at a young age, maybe they don’t have time to grow tumors in other organs.
How concerned should we be about bovine leukemia virus? “It is not clear whether this is good news or bad news.” If future research shows that BLV causes breast cancer in humans, there will be major implications for the dairy and cattle industries. But that means we can do something about it. Perhaps action should be taken now to eradicate the infection in cattle, rather than waiting for a final decision. Twenty-one nations have eliminated BLV from their dairy cattle. In contrast, the prevalence of BLV in the United States continues to increase. If the industries will not step up and try to eradicate this disease, then the least they can do is to eradicate some of the practices that spread the disease among animals.
BLV is spread through blood through contaminated needles, saws or dehorners, ear taggers, hoof knives, tattoo pliers, nose pliers, and other tools of the agribusiness trade. Although “due to the emerging knowledge about BLV in human breast cancer, it is prudent to promote the elimination of BLV in cattle, especially in the dairy industry.” The hope is that, either way, it can help reduce the scourge of breast cancer.
Doctor’s Note
If you missed the previous video, check it out Bovine Leukemia Virus as a cause of breast cancer.
Avoiding infectious risks like BLV is another benefit of producing meat without animals. See my video, Human Health Effects of Farmed Meat: Food Safety.
