Lifestyle Works

Role of Meat and Dairy
Viruses in Cancer

Nearly 20% of cancer cases arising worldwide can be linked to infectious agents, including viruses. Seven viruses are now conclusively tied to human cancers, and, as new viruses enter into human populations, the incidence and causes of cancer will likely change accordingly.

The foundation of modern tumor virology was laid more than a century ago with the discovery of a cancer-causing chicken virus, for which a Nobel Prize was awarded. Another Nobel Prize went to the medical doctor-turned-virologist who discovered that the HPV virus was causing cervical cancer. In his acceptance speech, he mused that there may be a bovine polyoma virus—a multiple tumor virus in cattle—that could be playing a role in human colon cancer, lung cancer, and breast cancer, but no polyoma virus had ever been discovered in meat…until now.

Polyomaviruses are a particular concern—not only because they are known to be carcinogenic, but also because they can survive cooking temperatures. Since a single burger these days can contain meat from many dozens of animals, researchers felt this could present an ideal situation for virus-hunting… Researchers from the National Cancer Institute purchased meat samples from three separate supermarkets and found three different polyomaviruses in ground beef. Now, just because three types of polyomavirus species are commonly detectable in food-grade ground beef doesn’t necessarily mean they are causing human disease. What made this Nobel laureate suspect them? Well, for one thing, some people got cancer right where they had been vaccinated for smallpox—a whole bunch of different cancers, in fact. The vaccine had been harvested from the skin of calves, so it is possible there could have been some cancer-causing cow virus.

Many people are exposed to potentially virus-contaminated meat and dairy products through their diets, but those in the industry, such as farm workers, butchers, veterinarians, and employees in dairies, would be even more exposed. Do these groups have higher cancer incidence? Indeed, it now appears to be clear that workers in the meat industry are at increased risk of developing and dying from cancer.

Another reason to suspect the involvement of some kind of bovine infectious factor in colorectal cancer is the fact that there appear to be relatively low rates of colorectal cancer in countries with low beef intake. And, when meat consumption suddenly increases, rates shoot up. The only exception is Mongolia where they have low rates of colon cancer and eat a lot of red meat, but there they eat yak. Maybe yaks don’t harbor the same viruses!!!

Even steak cooked medium may not reach internal temperatures above 70° Celsius, and it takes temperatures higher than that to inactivate some of these viruses, so we would expect viruses to survive both cooking and pasteurization. In fact, researchers followed up with a paper suggesting the consumption of dairy products may, represent one of the main risk factors for the development of breast cancer in humans. The recent discovery of a larger number of presumably new viruses in the blood, meat, and milk of dairy cows should be investigated, since one might speculate that infectious agents present in dairy products possess a higher affinity to mammary [breast] cells, since they came from breast (udder) cells. The fact that people with lactose intolerance, who tend to avoid milk and dairy throughout their lives, have lower rates of breast and other cancers could be seen as supporting this concept. Though, there are certainly other reasons dairy may increase cancer risk, such as increasing levels of the cancer-promoting growth hormone IGF-1 or adversely affecting our gut microbiome. Or, for that matter, maybe the plant-based milks they’re drinking instead could be protective. That’s the problem with population studies: You can’t tease out cause and effect. It doesn’t matter how many viruses are found in retail beef, pork, and chicken, if we can’t connect the dots.  

There’s still a lot of work to be done. But, if the link between bovine polyomaviruses and human disease pans out, the National Cancer Institute researchers envision the development of a high potency vaccine. So, just like the HPV vaccine may prevent cervical cancer from unsafe sex, perhaps one day, vaccines may prevent breast and colon cancer from unsafe sirloin!!!

 —Michael Greger M.D. FACLM on September 24th, 2020

Recipe of the Month

Chick Nuggets

1½ cup cooked chickpeas (or one tin)
1 tablespoon tamari
1 tablespoon tahini/peanut butter
1 teaspoon chicken style seasoning    
¼ cup potato flour
¼ cup oats
¼ cup sunflower seeds    
pinch of salt
1/3 cup non-dairy milk

Blend in food processor the oats, sunflower seeds and salt until coarsely ground. Remove from the processor, then blend chickpeas, tamari, tahini, seasoning and potato flour until smooth.
Form the chickpea mix into nugget-sized pieces, dip each one into the milk, then coat in oat/seed mix and place on a baking tray. Bake in the oven at 180°C for 30 minutes.
Makes 16 nuggets.
Serve with tomato sauce. —Ref. Highwood Recipes From The Kitchen , p.26