Saturday, November 11, 2017
Red meat triggers toxic immune reaction which causes cancer, scientists find
This has been said for some time. The big take home is that only chicken and surely fish are free of this sugar. Cheese is not.
Eating a pound and one half of cheese and red meats is a reasonable limit. That way you do not have to totally give it up.
I would like to see what can be done with fermentation as fermented ground meat can be an excellent product.
The whole sector of fermentation is in need of an extensive research effort.
Red meat triggers toxic immune reaction which causes cancer, scientists find
Scientists at the University of California discovered that the human body views red meat as a foreign invader and launches an immune response
The body views red meat as a foreign invader which must be stamped out
By Sarah Knapton, Science Editor
8:00PM GMT 29 Dec 2014
Red meat has been linked to cancer for decades, with research suggesting that eating large amounts of pork, beef or lamb raises the risk of deadly tumours.
But for the first time scientists think they know what is causing the effect. The body, it seems, views red meat as a foreign invader and sparks a toxic immune response.
Researchers have always been puzzled about how other mammals could eat a diet high in red meat without any adverse health consequences.
Now they have discovered that pork, beef and lamb contains a sugar which is naturally produced by other carnivores but not humans.
It means that when humans eat red meat, the body triggers an immune response to the foreign sugar, producing antibodies which spark inflammation, and eventually cancer.
In other carnivores the immune system does not kick in, because the sugar – called Neu5Gc – is already in the body.
Scientists at the University of California proved that mice which were genetically engineered so they did not produce Neu5Gc naturally developed tumours when they were fed the sugar.
"This is the first time we have directly shown that mimicking the exact situation in humans increases spontaneous cancers in mice,” said Dr Ajit Varki, Professor of Medicine and Cellular and Molecular Medicine at the University of California.
"The final proof in humans will be much harder to come by.
"This work may also help explain potential connections of red meat consumption to other diseases exacerbated by chronic inflammation, such as atherosclerosis and type 2 diabetes.
"Of course, moderate amounts of red meat can be a source of good nutrition for young people. We hope that our work will eventually lead the way to practical solutions for this catch-22."
Red meat is a good source of protein, vitamin and minerals, but an increasing body of research suggests too much is bad for long-term health.
Health experts recommend eating no more than 2.5oz (70g) a day, the equivalent of three slices of ham, one lamb chop or two slices of roast beef a day
A study published by Harvard University in June suggested that a diet high in red meat raised the risk of breast cancer for women by 22 per cent.
In 2005 a study found those who regularly ate 5.6oz (160g) of red meat a day had one third higher risk of bowel cancer.
The average person in the UK has 2.5oz (70g) meat a day 3oz (88g) among men, 2oz (52g) among women) but 33 per cent have more than 3.5oz (100g) a day.
Previous research has suggested that a pigment in red meat may also damage the DNA of cells lining the digestive system.
The new research was published online in the journal, Proceedings of the National Academy of Sciences.
Research news and views on preventing and surviving cancer
Study Gives New Insights on Red Meat, a Sugar, and Cancer
By Author Teresa
Research shows that eating high amounts of red meat increases risk of colorectal cancer, possibly because it may spur inflammation. A new animal study published in The Proceedings of the National Academies of Sciences now points to a sugar molecule found in red meat as one mechanism responsible.
The molecule called N-glycolylneuraminic acid, or Neu5Gc for short, sticks to the ends of sugars found in red meats such as beef, pork, and lamb. Although most mammals produce Neu5Gc, humans don’t. Humans are “immunized” against Neu5Gc shortly after birth by an unusual process involving gut bacteria. As a result, when people eat foods that contain Neu5Gc, we produce antibodies that react to Neu5Gc, triggering inflammation.
Previous research has detected relatively high amounts of Neu5Gc in cancerous tissue.
In foods, Neu5Gc can be free or it can be bound to the ends of long sugar chains attached to proteins. The bound form is highly bioavailable, meaning it can easily be taken up into the body’s cells. Neu5Gc tends to accumulate in cells of the colon, prostate, and ovary.
In the study, the researchers first assessed the Neu5Gc content in 62 commonly eaten foods, including dairy products, red meats, poultry, seafood, fruits, and vegetables. Whereas red meats had the highest amount of Neu5Gc, poultry, seafood (except caviar), fruits, and vegetables had none. Beef had the highest levels of all the categories of red meat. Cow’s milk had very little Neu5Gc but cheeses from cow’s milk or goat’s milk had levels comparable to red meats.
Cooking had no effect on Neu5Gc levels.
Then, using a special kind of mice that can’t produce Neu5Gc, they gauged the effect of dietary Neu5Gc on inflammation and tumors. For twelve weeks, they fed the Neu5Gc-deficient mice one of two diets – a Neu5Gc-free diet or a Neu5Gc-rich diet. (Mice have a shorter lifespan than humans so a 12-week Neu5Gc-rich diet simulated a human diet rich in red meat for many years.)
At the end of the 12-week period, they injected some of the mice with Neu5Gc antibodies, to mirror the antibody response of humans. It was only the mice that received both the Neu5Gc-rich diet and the antibodies that showed evidence of systemic inflammation.
Next, they fed a group of specialized mice either a Neu5Gc-rich diet or Neu5Gc-poor diet (control). The mice were prone to developing liver tumors and immunized against Neu5Gc to mimic human-like Neu5Gc immunity and the antibody response.
The mice consuming the Neu5Gc-rich diet had higher levels of inflammatory proteins, more lesions on their livers and eventually, more liver cancer than the animals eating no Neu5Gc.
In a similar experiment that was longer (85 weeks), mice that ate the Neu5Gc-rich diet and were immunized against Neu5Gc were five times more likely to develop liver tumors than non-immunized mice eating no Neu5Gc.
The researchers admit it’s difficult to apply the results of this study to humans because, unlike the mice, humans eat a varied diet and levels of Neu5Gc antibodies can vary from person to person. But the study does show some similarities to the situation in which people eat a diet high in red meat and, as a result, have higher rates of cancer, especially colorectal cancer.
More study is needed to determine exactly how eating red meat contributes to cancer risk. In the meantime, AICR recommends limiting consumption of red meat to 18 ounces (cooked) per week.
That’s roughly equivalent to a small lean hamburger or a small steak filet once a day.
This study was funded by a Samuel and Ruth Engelberg Fellowship from the Cancer Research Institute (to O.M.T.P.), the Swiss National Science Foundation (H.L.), the Ellison Medical Foundation (A.V.), and NIH Grant R01CA38701 (to A.V.). Teresa L. Johnson, MSPH, RDN, is a nutrition and health communications consultant with a long-time interest in the role of plant-based diets and cancer prevention. Her work draws on elements of nutritional biochemistry, phytochemistry, toxicology, and epidemiology.