The 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.

As I discuss in my video The Role of Burger Viruses in Cancer, 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, as you can see at 1:52 in my video. 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 where not a lot of beef is eaten. And, when meat consumption suddenly increases, rates shoot up, as you can see at 3:15 in my video. “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.

Can’t you just avoid steak tartare? 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 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, as you can see at 5:16 in my video, if we can’t connect the dots.  

Can’t we just look for the presence of these viruses within human tumors? Researchers have tried and did find some, but even if you don’t find any, that doesn’t necessarily mean viruses didn’t play a role. There’s a “viral hit-and-run” theory of cancer development that suggests that certain viruses can slip in and out of our DNA to initiate the cancer, but be long gone by the time the tumor matures.

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.


This reminds me of the story of bovine leukemia virus and breast cancer. For more on that, see:

What about chicken? Check out The Role of Poultry Viruses in Human Cancers and Poultry and Penis Cancer.

One of the problems with eating other animals is that we put ourselves at risk of their diseases. Not once have I diagnosed anyone with Dutch Elm Disease or a really bad case of aphids. See Eating Outside Our Kingdom for more on this concept.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

 

 

Vitamin C for Male Infertility and Lead Poisoning?

What is the clinical relevance of vitamin C among lead-exposed infertile men? Compared to controls, lead battery industry workers given 1,000 mg of vitamin C every workday for three months experienced “a significant increase in sperm motility and sperm count, as well as decrease in abnormal sperm,” and “a significant reduction in the incidence of sperm DNA fragmentation,” that is, damaged sperm DNA. Okay, but the ideal endpoint would be bouncing baby boys and girls. Enter this extraordinary little study from the University of Texas from more than 30 years ago.

Twenty-seven men with fertile wives had been trying to have kids for years to no avail. Twenty of them were given 1,000 mg of vitamin C a day for two months, and 7 acted as controls and didn’t get any vitamin C. The researchers followed up at the end of the 60 days. By then, every single one of the wives of each of the 20 men who had gotten the vitamin C had became pregnant—20 out of 20! After years of frustration, boom: 100-percent pregnant. What’s more, not a single one of the wives of men in the control group got pregnant. Rarely does one see these kinds of black-and-white results in the medical literature for any intervention.

Is the vitamin C lowering the oxidative stress from the lead, or is it actually lowering the level of lead? Sure, antioxidant supplementation can have antioxidant effects, but it may fail to actually lower lead levels in the blood. Now, this was in a group of workers who were breathing lead day in and day out, and the way vitamin C may work is by simply blocking the “intestinal absorption of lead.” An earlier study showed vitamin C supplementation apparently cut lead levels by a third within six months, but that was with a whopping dose of 2 g with added zinc. Another small study found the same 30 percent drop with just 500 mg a day, no zinc, and in only one month. But neither of those studies had a control group of subjects who didn’t take anything, so we don’t know if their levels would have fallen anyway.

Similarly, there is an almost too-good-to-be-true study on the role of vitamin C in scavenging lead toxicity from “biosystems,” by which they meant children. They got 250 to 500 mg a day of vitamin C for a few months, and shaved hair samples every month saw up to a 69 percent decline in lead levels. Researchers repeated it in two other small groups of kids and saw the same amazing kind of drops in every single child. But maybe lead levels were just dropping throughout the whole community during that time? Without measuring lead levels in a control group of kids not taking vitamin C, we can’t be sure.

As I illustrate from 3:17 in my video Yellow Bell Peppers for Male Infertility and Lead Poisoning?, with eight weeks of vitamin C, lead levels dropped in the blood and rose in the urine. One could conclude that the vitamin C was pulling lead out of the body, but the same thing happened in the placebo group: Blood levels dropped, and urine levels rose. So, it had nothing to do with the vitamin C at all. That’s why it’s always important to have a control group.

The same applies with studies that appeared to show no benefit. For example, 36 battery manufacturing workers were studied. Each was given vitamin C, yet there was no change in their lead levels. But, maybe their co-workers suffered a big increase in lead levels during that same time period, and the vitamin C was actually successful in keeping the subjects’ levels from rising. You don’t know without a control group.

That’s why studies like “The effects of vitamin C supplementation on blood and hair levels of cadmium, lead, and mercury” are so important. Vitamin C versus an identical-looking sugar pill placebo. The result? The vitamin C failed to help, which really put a damper on enthusiasm for using vitamin C for lead poisoning until a now-famous study was published in 1999 that showed that vitamin C supplementation could lead to a decrease in blood levels. As you can see at 4:32 in my video, after four weeks of taking a placebo, not much change occurred in blood lead levels in the control group, which is what we’d expect. In contrast, the vitamin C group started out at about the same blood lead level as the control group, but within one week of taking 1,000 mg of vitamin C a day, lead levels dropped 81 percent. So, supplementation of vitamin C “may provide an economical and convenient method of reducing blood-lead levels, possibly by reducing the intestinal absorption of lead.”

The urine lead levels didn’t change, so it’s not as if the subjects were excreting more lead in their urine to bring down their blood levels. However, most of the lead in our blood is in the red blood cells, which are recycled in the liver and discharged through the bile into the gut where the lead could just get reabsorbed—unless, perhaps, you’ve got a lot of vitamin C in there to block the re-absorption. But 1,000 mg is a lot of vitamin C. Would something like 200 mg, which is just about how much vitamin C you’d get in an orange and a cup of broccoli or strawberries, work? The researchers tested that, too. The 200 mg group started out the same as the control and the 1,000 mg group, but blood lead levels didn’t really budge. Bummer! So, 1,000 mg seemed to work, but 200 mg didn’t. Isn’t 1,000 mg of vitamin C a bit unnatural, though? The RDA is only 60 mg. Well, actually, we may have evolved for millions of years getting closer to 600 mg a day—ten times the current RDA—because we were eating so many fruits and greens. Okay, but could you reach 1,000 mg of vitamin C without having to take pills? Yes! That’s the amount of vitamin C, for example, that can be found in three yellow bell peppers.


Other videos in my series on lead include:

Note that there is nothing special about yellow bell peppers—other than their extraordinary vitamin C content, that is. I just used them as a practical way to get 1,000 mg of vitamin C in whole-food form. They’re certainly easier than eating ten oranges!

Though, remember my video Peppers and Parkinson’s: The Benefits of Smoking Without the Risks? So, one would expect to get all the benefits of the 1,000 mg of vitamin C with benefits. Why not just take vitamin C supplements? See Do Vitamin C Supplements Prevent Colds but Cause Kidney Stones?.

If hundreds of milligrams a day of vitamin C sounds like a lot, check out What Is the Optimal Vitamin C intake?.

You may be interested in my vitamin C and cancer series:

Finally, for more on male fertility, see:

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

Preorder the How Not to Diet Cookbook & Get a Signed Bookplate!

I’m thrilled to announce that The How Not to Diet Cookbook is now available for preorder for everyone on your holiday gift list! If you have my first one, The How Not to Die Cookbook, you’ll recognize the one-and-only Robin Robertson joined me again to develop over 100 whole food, plant-based recipes inspired by cuisines around the world. Here’s a tiny sample of what’s in my new cookbook: 

  • Red Bean and Butternut Caldo Verde
  • Thai Green Papaya Salad
  • Zucchini Linguini with Mushroom-Lentil Bolongese
  • Jicama Nachos
  • Black Forest Chia Pudding

Not only is every recipe health-promoting, but every ingredient of every recipe is healthful. All recipes are composed of 100% Green-Light ingredients. But how do you make things sweet without sugar? Salty without salt? Those were some of the challenges that made creating the cookbook so much fun!

Specific to the 21 Tweaks for evidence-based weight loss I detailed in How Not to Diet, recipes include the foods that act as fat blockers and fat burners, and starch blockers and appetite suppressants, such as black cumin, vinegar, and my prebiotic BROL mixture. The recipes that meet my “negative calorie” preloading criteria are clearly marked. If you haven’t read How Not to Diet yet, grab a copy from your local library or wherever you buy or borrow your books.

Preorder your copy of my new cookbook today, and books will be arriving December 8, just in time for the holidays and your New Year, New You resolutions.

Get a Signed Bookplate
For a limited time, donate any amount to NutritionFacts.org using this form to receive a signed bookplate to put in your copy as a thank you gift. The bookplates also make a great keepsake for any of your copies of How Not to Diet, How Not to Die, or The How Not to Die Cookbook. All proceeds go to keeping the 501(c)3 nonprofit organization NutritionFacts growing and going. Donate today since this form will only be up until my hand cramps up. 🙂

 

Videos on Plant-Based Meats Available for Download

Thank you to everyone who joined my recent webinar, The Human Health Implications of Plant-Based and Cultivated Meat for Pandemic Prevention and Climate Mitigation. The high-quality digital download of the videos from that webinar is now available on DrGreger.org. These videos will eventually be on NutritionFacts.org for free, but if you don’t want to wait, you can get them right now.

 

 

 

 

New Comment Platform Coming Soon

Green-Speech-BubbleLongtime users of NutritionFacts.org will be familiar with this change – we are returning to Disqus for the comments on the website. This will allow us to have more features that many of you have been requesting. You will be able to log in via Disqus.com, using your social media, or you can create and reply to comments without logging in at all. It also means that we will be saying goodbye to the user logins on NutritionFacts.org, so if you have any videos saved to your “favorites,” now is the time to save those links on your computer before the function goes away. These changes will be rolling out in the next few weeks. 
 
 
 
 

Just Ask Alexa!  

Wellian-Dr.GregerA company called Wellian has developed an Alexa app that lets you tap into NutritionFacts.org’s information straight from your Alexa device. Simply subscribe, activate the app, and ask questions like “What causes heart disease?” or “How to improve my immune system?” Learn more about Wellian with Alexa. I can’t wait to try it! 

 

 

 

Doctor and Dietitian Q&A

Join me for another live Instagram Q&A with one of my favorite dietitians and dearest friends, Julieanna Hever.
Head over to the NutritionFacts.org Instagram page on 9/18 at 3pm ET to get the answers to your health and nutrition questions.

 

 

 

 

Top 3 Videos of the Month

Do Vegetarians Really Have Higher Stroke Risk?

 

Do Vegetarians Really Have Higher Stroke Risk?

The first study in history on the incidence of stroke of vegetarians and vegans suggests they may be at higher risk.

 

 

Vegetarians and Stroke Risk Factors—Vitamin B12 & Homocysteine?

 

Vegetarians and Stroke Risk Factors—B12 & Homocysteine?

Not taking B12 supplements or regularly eating B12 fortified foods may explain the higher stroke risk found among vegetarians.

 

 

Flashback Friday: Coconut Oil and Abdominal Fat

What does a review of the evidence on the effects of coconut oil on weight loss and belly fat find?

 

 

 

Live Q&A on Sept 24

Every month I do a live Q&A from my treadmill, and this month Sept 24 is the day.

Join on our Facebook page or YouTube channel at 3pm ET.  I’ll be streaming to both at the same time!

You can now find links to all of my past live Q&As here on NutritionFacts.org. If that’s not enough, remember I have an audio podcast to keep you company at nutritionfacts.org/audio.

 

 

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: