Virus in Chicken Could Be Linked to Obesity

NF-May31 Infectobesity Adenovirus 36 and Childhood Obesity.jpeg

Recently, there has been research examining the connection between poultry consumption and weight gain. One study out of the Netherlands examining about 4,000 people, correlated chicken consumption with weight gain. Another study followed 89,000 people in four other countries and found that animal protein intake was associated with long-term weight gain, and poultry was the worst, with 40 percent more weight gain than red meat or processed meat.

What makes poultry so bad? Yes, chickens are fatty these days because of the way we've genetically manipulated them--up to ten times more fat and calories than they used to have--but one bizarre theory postulated that it might be due to an obesity-causing chicken virus. In one study, one in five obese humans tested positive to the chicken virus SMAM-1, with those exposed to the chicken virus averaging 33 pounds heavier than those testing negative.

SMAM-1 was the first chicken virus to be associated with human obesity, but not the last. The original obesity-causing chicken virus SMAM-1 was able to effectively transmit obesity from one chicken to another when caged together, similar to a human adenovirus Ad-36, a human obesity-associated virus first associated with obesity in chickens and mice. Ad-36 spreads quickly from one chicken to another via nasal, oral or fecal excretion and contamination, causing obesity in each chicken. This of course raises serious concerns about Ad-36-induced adiposity in humans.

The easiest way to test this hypothesis is to experimentally infect humans with the virus. However, ethical reasons preclude experimental infection of humans, and so the evidence will have to remain indirect. In the absence of direct experimental data, we must rely on population studies, similar to how researchers nailed smoking and lung cancer. About 15 percent of Americans are already infected with Ad-36, so we can follow them and see what happens. That's exactly what a research team out of Taiwan did (highlighted in my video Infectobesity: Adenovirus 36 and Childhood Obesity). They followed 1,400 Hispanic men and women for a decade and found that not only were those exposed to the virus fatter than those who were not, but also over the ten years, those with a history of infection had a greater percentage of body fat over time.

Most studies done to date on adults have found a connection between exposure to Ad-36 and obesity, and all studies done so far on childhood obesity show an increase in prevalence of infection in obese children compared to non-obese children. We're now up to more than a thousand children studied with similar findings. Obese children who tested positive for the virus weighed 35 pounds more than children who tested negative.

The virus appears to both increase the number of fat cells by mobilizing precursor stem cells and increase the accumulation of fat within the cells. If we take liposuction samples of fat from people, the fat cell precursors turn into fat cells at about five times the rate in people who came to the liposuction clinic already infected. Fat taken from non-infected people that was then exposed to the virus start sucking up fat at a faster rate, potentially inducing obesity without increasing food intake.

Just as Ad-36 can be transmitted horizontally from one infected chicken to another in the same cage, subsequently causing obesity in each chicken, this same virus is also easily transmitted among humans, raising the question as to whether at least some cases of childhood obesity can be considered an infectious disease. Researchers publishing in the International Journal of Pediatric Obesity speculate that this animal adenovirus may have mutated to become a human adenovirus capable of infecting humans and causing obesity.

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 Uprooting the Leading Causes of Death, More Than an Apple a Day, From Table to Able, and Food as Medicine.

Image Credit: Glasseyes view / Flickr

Original Link

How Animal Proteins May Trigger Autoimmune Disease

NF-July3 Animal Proteins and Virus Triggering Diseases.jpg

Although slaughterhouse workers with the most poultry exposure appear to suffer the greatest excess mortality (see Poultry Exposure Tied to Liver and Pancreatic Cancer), increased risk of death from cancer is also found in other slaughterplant workers. This research goes back decades and shows higher cancer rates in butchers, slaughterhouse workers, meat cutters, and those working in meat processing plants.

The increased risk for meat industry workers in developing and dying from cancer "may be due to animal-to-human viruses or antigenic stimulation through chronic exposure to animal protein." Cancer-causing virus exposure could also help explain why those who eat meat have higher cancer rates. There's even a retrovirus associated with cancerous fish tumors, which has been speculated as the cause for increased cancer rates in American seafood workers.

Growing up on a livestock farm is associated with higher rates of blood-borne cancer, lymphomas and leukemia. Worst, though, is growing up on a poultry farm, which is consistent with chicken consumption being most closely tied to these cancers. Eating a quarter of a chicken breast daily is associated with a doubling or tripling of risk for these cancers (see EPIC Findings on Lymphoma). Growing up on a farm raising only plant crops, however, is not associated with blood-borne cancers.

What about growing up with dogs and cats? See Pets & Human Lymphoma and Are Cats or Dogs More Protective for Children's Health? You still probably shouldn't eat them, though (see Foodborne Rabies).

Researchers are finally able to start connecting the dots. High levels of antibodies to avian leucosis/sarcoma viruses and reticuloendotheliosis viruses in poultry workers provide evidence of infectious exposure to these cancer-causing poultry viruses. The highest levels were found not in the eviscerators, or gut-pullers, or those that hang the live birds, but among the line workers that just cut up the final product.

In an attempt to narrow down which diseases were associated with which meat, researchers tried separating out those in pig slaughtering and pork processing. "One of the primary sources of concern in using pig organs and tissues as transplants in humans is the fear of introducing zoonotic infections" from animals. We're concerned about what's called PERV transmission, the pig-to-human transmission of porcine endogenous retroviruses, raising theoretical concerns about cancer, immunological, and neurological disorders. However, we don't need to get a pig transplant to be exposed. PERVs are also found in blood, so people exposed to pig blood may be exposed to the virus.

The main finding unique to the pork study (profiled in my video Eating Outside Our Kingdom), which was not found in beef and sheep processing, was the significant excess of deaths "from senile conditions such as Alzheimer's disease." It reminds me of all those poor pork brain extraction workers. You think your job is bad? How would you like to work at the "head-table"? Well, that doesn't sound so bad until you learn it's where, through the "unbridled use of compressed air in the pursuit of maximum yield of soft tissue," they remove the brains of severed swine heads.

In one study, researchers noted that as the line speeds increased, "the workers reported being unable to place the skulls completely on the brain removal device before triggering the compressed air, causing greater splatter of brain material." The aerosolized "mist of brain" is suspected to be the cause of dozens of cases of inflammatory neurological disease in workers who started with symptoms as mild as pain, tingling, and difficulty walking, and ended up so bad that doctors had to put them in a coma for six weeks because of unrelenting seizures.

At first researchers thought it was a brain parasite, but now it's known to be an auto-immune attack triggered by the exposure to aerosolized brain. A similar mechanism has been blamed for meat proteins triggering inflammatory arthritis in people eating meat. By eating fellow animals, we are exposed not only to fellow animal diseases, but to animal tissues that our body may mistake as our own. This may be one advantage to eating a more plant-based diet. By eating outside of the animal kingdom--dipping into the plant or mushroom kingdoms for supper--not only do we not have to worry about getting something like Dutch elm disease, but we can be reassured by the fact that never has an "auto-immune polyradiculoneuropathy" been blamed on a head... of lettuce.

For more on foodborne illnesses one can contract from fellow animals, see, for example:

Probably the strangest example of this whole concept is the Neu5Gc story. A 7-part video series worth checking out:

  1. Cancer as an Autoimmune Disease
  2. Clonal Selection Theory of Immunity
  3. Clonal Deletion Theory of Immunity
  4. The Inflammatory Meat Molecule Neu5Gc
  5. How Tumors Use Meat to Grow: Xeno-Autoantibodies
  6. Nonhuman Molecules Lining Our Arteries
  7. Meat May Exceed Daily Allowance of Irony

-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 Uprooting the Leading Causes of Death and More Than an Apple a Day.

Image Credit: vgm8383 / Flickr

Original Link

Handling Poultry Tied to Liver/Pancreatic Cancers

NF-July1 Poultry Exposure Tied to Liver and Pancreas Cancer.jpg

Thousands of Americans continue to die from asbestos exposure decades after many uses were banned since the cancers can take years to show up. We are now in the so-called "third wave" of asbestos-related disease. The first wave was in the asbestos miners, which started in the 1920s. The second phase was in the workers--the ship-builders and construction workers that used the stuff in the '30s, '40s, and '50s.

Now, as buildings "constructed with asbestos over the past six decades begin to age and deteriorate," not only are workers at risk, but "potential also exists for serious environmental exposure to asbestos among residents, tenants and users of these buildings, such as school children, office workers, maintenance workers, and the general public."

"The Centers for Disease Control, the American Academy of Pediatrics, and the U.S. Environmental Protection Agency have projected that over the next 30 years approximately 1,000 cases of mesothelioma and lung cancer will occur among persons in the United States exposed to asbestos in school buildings as school children."

To see if something is carcinogenic, we study those who have the most exposure. That's how we learned about the potential cancer-causing dangers of asbestos, and that's how we're learning about the potential cancer-causing dangers of poultry viruses. For years I've talked about the excess mortality in poultry workers associated with these wart-causing chicken cancer viruses that may be transmitted to those in the general population handling fresh or frozen chicken (See Wart Cancer Viruses in Food). Last year I talked about the largest study at the time "confirming the findings of three other studies to date that workers in poultry slaughtering and processing plants have increased risk of dying from certain cancers," that also added penis cancer to the risks linked to poultry exposure (See Poultry and Penis Cancer). That was looking at 20,000 poultry workers. Well, we have yet another study, now looking at 30,000.

The purpose of the study, profiled in my video, Poultry Tied to Liver and Pancreatic Cancer, was to test the hypothesis that exposure to poultry cancer-causing viruses that widely occurs occupationally in poultry workers--not to mention the general population--may be associated with increased risks of deaths from liver and pancreatic cancers. They found that those who slaughter chickens have about nine times the odds of both pancreatic cancer and liver cancer.

Just to put this in context, the most carefully studied risk factor for pancreatic cancer, one of our deadliest cancers, is cigarette smoking. Even if we smoke for more than 50 years, though, we "only" about double our odds of pancreatic cancer. Those who slaughter poultry appear to have nearly nine times the odds.

For liver cancer the most well-known and studied cause is alcohol. Those who consume more than four drinks a day have triple the odds of liver cancer. As with pancreatic cancer, poultry slaughtering appears to increase one's odds of getting liver cancer nine-fold. Thus, the cancer-causing viruses in poultry may explain the increasing risk of death from liver and pancreatic cancers.

There are diseases unique to the meat industry like the newly described "salami brusher's disease" that affects those whose job it is to wire brush off the white mold that naturally grows on salami for eight hours a day, but most diseases suffered by meat workers are more universal. The reason the connection between asbestos and cancer was so easy to nail down is that asbestos caused a particularly unusual cancer, which was virtually unknown until there was widespread asbestos mining and industrial use. The pancreatic cancer one might get from handling chicken, however, is the same pancreatic cancer one might get smoking cigarettes, so it's more difficult to tease out a cause-and-effect-relationship. Bottom line: despite the extremely high risks of deadly cancers, don't expect an asbestos-type ban on Kentucky Fried Chicken anytime soon.

I've addressed this topic before. See:

It's ironic that the meat industry wants to add viruses to meat (Viral Meat Spray) to combat fecal bacterial contamination. I'd take that over their other bright idea any day, though (Maggot Meat Spray).

A human wart virus, HPV, can be combated with green tea (Treating Genital Warts with Green Tea), as well as by plant-based diets in general (Why Might Vegetarians Have Less HPV?).

Although workers with the most poultry exposure appear to suffer the greatest excess mortality, increased deaths from cancer are also found in other slaughterhouse workers. More on that in Eating Outside Our Kingdom.

-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 Uprooting the Leading Causes of Death and More Than an Apple a Day.

Image Credit: Peter Cooper / Flickr

Original Link