Estrogenic Growth Promoters in Meat

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Estrogenic Growth Promoters in Meat

In 1979, an epidemic of breast enlargement was noted in Italian children. Poultry or veal was suspected, given that estrogens “may be fed to farm animals to accelerate their weight gain.” “After this episode, the European Union banned the application/use of anabolic growth promoters in agriculture,” as well as the importation of American meat from animals injected with drugs like Zeranol, sold as “Ralgro Magnum.”

Zeranol, one of the most potent known endocrine disrupters, is 100,000 times more estrogenic than the plastics chemical, BPA, for example, and is the subject of my video Zeranol Use in Meat and Breast Cancer. “Zeranol constitutes a special case among potential endocrine disrupters, because Zeranol, in contrast to all other oestrogenic ‘endocrine disrupting’ chemicals, is present in human food because it is deliberately used in the production of consumer products. Furthermore, Zeranol is designed to be a potent, fairly persistent, [estrogen] whereas the [estrogenic] properties of the chemicals that are considered potential endocrine disrupters is accidental.”

If you drip blood from a cow implanted with the drug onto human breast cancer cells in a petri dish, you can double the cancer growth rate. We don’t drink blood, though, but preliminary data showed that muscle extracts—that is, meat extracts—also stimulated breast cancer cell proliferation.

Furthermore, Zeranol may cause the transformation of normal breast cells into cancer cells in the first place. Zeranol-containing blood from implanted cattle “was capable of transforming the human normal breast epithelial cell line” into breast cancer cells within 21 days.

“[O]bese individuals may be at greater risk of developing zeranol-induced breast cancer,” since they already have high levels of leptin, which is a hormone produced by fat cells that can itself promote breast cancer growth. And, Zeranol exposure can greatly enhance this growth-promoting action. “This result also suggests that Z[eranol] may be more harmful to obese breast cancer patients than to normal weight breast cancer patients in terms of breast cancer development.”

“In conclusion, because the synthetic and the natural hormones, used as anabolic growth promoters in meat production, are by far the most potent hormones found in human food,” we should really be testing people, especially children, before and after eating this meat. It amazes me this hasn’t been done, and, until it has, we have no idea what kind of threat they may pose, though the fact that Zeranol is as potent as estradiol (the primary sex steroid in women) and DES should concern us. DES is another synthetic estrogen that was marketed to pregnant women until 1971 when it was shown to cause vaginal cancers in the daughters. But few know it was also used in meat.

“In the absence of effective federal regulation, the meat industry uses hundreds of animal feed additives…with little or no concern about the carcinogenic and other toxic effects of dietary residues of these additives. Illustratively, after decades of misleading assurances of the safety of diethylstilbestrol (DES) and its use as a growth-promoting animal-feed additive, the United States finally banned its use in 1979 some 40 years after it was first shown to be carcinogenic. The meat industry then promptly switched to other [potentially] carcinogenic additives,” such as Zeranol.

When girls started dying from vaginal cancer, DES-treated meat was banned in Europe. However, “misleading assurances…including the deliberate suppression of residue data, managed to delay a U.S. ban on DES” in the meat supply for eight years.

Today, “[v]irtually the entire U.S. population consumes, without any warning, labeling, or information, unknown and unpredictable amounts of hormonal residues in meat products over a lifetime.” If all hormonal and other carcinogenic feed additives aren’t banned immediately, the least we should have is “explicit labeling requirements of use and of [hormone] residue levels in all meat products, including milk and eggs.”

Isn’t the DES story amazing? I had no idea it was used in meat production. Check out Illegal Drugs in Chicken Feathers for more on Big Pharma on Big Farms.

The most dangerous additive used in the meat industry is antibiotics, though. See, for example:

For more on what may be bad for the breast, check out:

And, for what may be protective, 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, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

42 responses to “Estrogenic Growth Promoters in Meat

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  1. Leptin and cancer growth seems like it would be an interesting topic and relevant to society “at large” pun and not a pun intended.

  2. I remember listening to a program on the local public radio station back in the early ’70’s about DES. They were giving it to the animals in the feed lots of Chicago. I mentioned it to my mother in law and she told me she took the drug for morning sickness with her last child. The both of them had to go for exams every 6 mos. Thank God nothing was found after 5 years.. lucky. After she told me of her experience that was the day I stopped eating red meat..Mamma did not raise no dummy. DES given to women cause cancer.. DES given to cows. Don’t eat red meat..

    1. I’m a DES daughter. At age 42 I had a stage 3 triple negative tumor in my breast. There’s absolutely no family history of breast cancer. I was mostly veg since about age 20. Although I followed the mainstream medical approach of mastectomy and chemotherapy, after cancer I followed a strict macrobiotic diet for several years. I’ve lapsed but still mostly vegan. I credit good doctors, good lifestyle as well as luck for being healthy and cancer-free 20 years later.

      DES also causes other reproductive disorders. It can cause uterine cancer and malformation of the uterus. And it may affect men exposed as well (obviously in different ways).

      1. Diane J — good for you for taking charge of your own health! My aunt, after a number if miscarriages was given DES in the 60’s and her only child, her daughter suffered many of the same issues you have.

        1. Awww, that has to be so hard.

          Mother’s worst nightmares would be to have a child suffer as a result of something like that.

    2. Mitch:

      It is my understanding that farmers raising 100% grass fed cows do not feed such chemicals to their cows. So saying “eat no red meat” is overly broad.

      1. “It is my understanding that farmers raising 100% grass fed cows do not feed such chemicals to their cows. So saying “eat no red meat” is overly broad.”

        Okay then, how’s about just saying ‘no’ to TMAO…

          1. TMAO:

            However, I am NOT a promoter of ‘chicken’ or any other ‘animal’ foods, as they have their own problems (as pointed out many times by Dr. Greger).


      2. The blog post notes

        “In conclusion, because the synthetic and the natural hormones, used as anabolic growth promoters in meat production, are by far the most potent hormones found in human food,”

        They may well not feed their cows synthetic hormones, but I wonder if farmers raising 100% grass fed cows feed natural growth hormones to their cattle. In any case, in countries like Uruguay, where all the cattle are grass fed, the more beef people eat, the higher the rates of cancer.

        ‘ Our results confirm earlier findingsof increased risk of gastrointestinal cancers with higher meat intake and suggest that meat consumption increasesthe risk of multiple other cancer sites.’

        not just total meat either ‘and similar findings were found with red meat, beef and lamb’

      3. Hey Sid, thanks for the reply.. I try to stay away from animal products.. I’m a plant kind of guy,,, YMMV.. works for me

      4. Personal choices. Nearly everyday we hear warnings about unsafe food products; more to come as they are discovered. I will not take the risk that farm run-off or arial sprays don’t effect cattle-even those grass-fed. For me and my family, we stick with safer WFPB.

        1. Lainey,

          If you really want to get into hyperdrive re: poultry and meat see the industry magazine, National Provisioner….. eye opening. And for food safety: which includes veggies and other products when it comes to clean, safe food considerations and what’s happening both in terms of regulatory and in the industry.

          The good news is that the industry recognizes the need for safer food, hence FSMA and other new regulations. Is it enough…. take the time to go and tour some food factories. Great learning experience and some/many are doing great work to insure safety others, hmmmm.

          And I agree with you, going WFPB is the better approach…..

          Dr. Alan Kadish moderator for Dr. Greger

    3. Cows given Stilbestrol became nymphomaniac and would attempt to mount other cows. At the same time, these cows would develop softening of the pelvic ligaments. “A combination of these two often results in a fractured pelvis”.
      C.E. Dodds, Biochemical Contributions to Endocrinology (1957). page 50.

  3. I looked at the study about Zeranol transforming the cells into cancer cells.

    It said a sentence about doubling time: “….decrease the doubling time of the cells by 30 to 40%”

    It mentally brought me back to Dr. McDougall’s information on doubling time.

    He said that the average doubling time is 100 days or 3-1/2 months and that it takes about 30 doubling times for it to become a visible tumor.

    If continued consumption of this decreased the number of years it takes to have a visible tumor by 30 to 40% that would be significant even without the leptin speeding things up.

  4. 3 minutes until Dr. Greger is on WHOLE Life Action Hour Series at the Food Revolution Network.

    If anybody is newer, I think the Whole Life Action Hour is good for people who are still figuring things out.

    The Culinary Gym is another site, which would probably be good for beginners.

    Not sure any beginners will show up, but I am posting those resources in case they do.

    It has helped me to start having some communities.

    I have barely started with that, but I know that it might be what makes the biggest difference because I don’t have anyone else in my life who is Whole Food Plant Based so it is harder to walk through every thing.

  5. A half hour into Dr. Greger’s interview.

    Boy, Dr. Greger, you are so fabulous at longer formats.

    I know that you have such a busy schedule that we won’t get to see that, but that already is one of my favorite interviews. Packed full of information.

  6. So is there a solution? Is organic meat or grass fed meat free of hormones? Can we trust labels that say no hormones? Is not eating meet the only answer? Would help your regular readers to provide such information in a scare story like this.

    1. caffrey,

      Dr. Greger does have videos on organic grass-fed meat and it is slightly better than regular meat, but it tends to be only slightly better.

      Most of the Whole Food Plant-Based oriented doctors recommend using meat more like a condiment, rather than as a main course. 5% of the calories or less coming from animal products is what they recommend.

      1. caffrey,

        Most of the people here are not vegan. They do try to eat as Whole Food Plant-Based as possible.

        When I came, I didn’t believe that I would go vegan, but I have.

        I think that focusing on adding in the beans and lentils and vegetables and berries is where you might suddenly be eating less meat without even knowing it happened.

      2. Deb and Caffeyc1945:

        There is a difference between organic beef and 100% grass fed beef. Organic beef are fed organic corn and organic wheat. Corn and wheat are bad for cows whether or not the corn and wheat is standard or organic. 100% grass fed is much better than organic beef.

          1. Sydney,

            I don’t have time to really look it up, but I went to a pro-grass-fed beef person and he said that in the USA, organic livestock are required to get at least 30 percent of their nutrition from pasture, but the animals are exempt from this requirement the last fifth of their lives.

            He said, “The organic label therefore tells you nothing about the animal’s diet—in fact, most organic meat in the U.S. is fed at least some grain prior to slaughter.”

            I can’t find the Dr. Greger article or video I was looking for. There are things like IGF-1 and the fact that almost every sample of beef tested has fecal matter on it and AGE’s and how the bad bacteria can use the carnitine for cancer. The list is pretty high of other factors.

            1. A study from Texas Tech University demonstrated that there is no difference in cholesterol in ground beef from grass-fed and grain-fed cattle if the fat content of both is similar, for instance.

              1. Deb

                I think that that particular university department gets most if not all of its funding from the cattle industry so there is perhaps a need to protect ‘conventional’ beef producers.

                If I rembemer correctly though, the fatty acid profile of grass-fed and organic beef is superior to that of conventional beef. Of course, it still has all the haem iron, cholesterol, IGF1 and natural growth hormones found in conventional beef And also appears to increase cancer rates (see my other post about the Uruguay study for a reference).

                1. LG King has already mentioned TMAO, courtesy of Dr Mirkin.

                  Let’s not also forget another substance found in all red meat including grass fed


                  In 1982, Professor Ajit Varki of the University of California San Diego discovered a sugar-protein molecule (called Neu5Gc) that appears in the tissues of almost every mammal except humans (Proc Nat Acad of Sciences, Sept 29, 2003). When you eat mammal meat, the Neu5Gc from the meat is absorbed into your bloodstream and your immune system treats this sugar-protein in the same way that it treats germs that try to get into your cells. Your immune system recognizes germs by the sugar-proteins on the surface of their cells. If the surface proteins are the same as those on your own cells, your immune system lets the protein enter you cells, but if the surface proteins on membranes are different from those on your cells, your immune system tries to kill the invading germs. Eating mammal meat turns on your immune system just as germs do, and if you eat mammal meat regularly, your immune system will stay active all the time. This is called inflammation. The same cells and chemicals that attack and kill germs can punch holes in your arteries to form plaques that can break off to lead to a heart attack. People who have the most markers of an overactive immunity are the ones most likely to suffer, and die from, heart attacks (J of Nutr, May 22, 2019).’

                  That was also from Dr Mirkin (his 30 May 2019 newsletter). In that newsletter, he also provides a link to his article on why even eating meat occasionally may be harmful


                  My own opinion is that if one is going to include a small amount of animal food in a WFPB diet, it should be small, wild caught oily fish. But not too much.


                  1. Tom,

                    Those are great additions to the discussion.

                    Yes, I chose industry-friendly sources. I knew that.

                    It was just the first things which came up and I didn’t have time to really search for the good information.

    2. caffey

      So, providing factual information is really just a ‘scare story’ ? Really?

      This is like the claim that discussing the relevant scientific evidence is just ‘demonising’ meat/cholesterol/saturated fat.

      When even the World Health Organization says that processed meat is carcinogenic and red meat is probably carcinogenic, the most important question to me at least isn’t how to come up with a justification for continuing to eat meat.

  7. We are all guinea pigs in this giant toxic slurry of the chemical age and the only ones protecting us is ourselves.

    1. We are all guinea pigs in this giant toxic slurry of the chemical age and the only ones protecting us is ourselves.

      That is such a powerful sentence.

      Wow, so well-written.

      It could be on a poster or in an ad campaign. Not kidding.

  8. The article mentions both Europe and the U.S.A., but does the same apply to Canadian meat?? I suspect it does, but there is a lot of marketing ads stating that our beef is “free of hormones and antibiotics”. Is it??

    p.s. I am vegan, and the more research I do, the happier I am with that choice!

    1. I looked at a site about beef in Canada and it said,

      “In Canada, growth hormones are only approved for use in cows used for beef. They help to produce leaner beef at a lower cost to consumers by helping cows convert the food they eat into muscle more quickly and easily. Hormones also occur naturally in all animals, people and plants. So there is no hormone-free beef. Growth hormones are not used in cows that produce milk.”

  9. This is only related as in the word “estrogenic” is something I read recently. There is a native plant that grows wild in the backyard (Southern US, etc.) that turns out has edible leaves that taste and feel similar to spinach.

    It is called Jewels of Opar, Talinum paniculatum. (It is a plant that apparently helped people in Brazil when there was less food.) What little nutrition information I found was in Portuguese that I used an Internet translator for. It said it may have estrogenic properties but I don’t know if that’s safe that it comes from a plant or it’s not safe. Any thoughts anybody? Thank you in advance!

    1. It’s my understanding that phytoestrogens, like in soy and this plant you mention, are processed by the body differently than animal estrogens in meat and dairy.

      They’re not a problem, and are actually beneficial.

    2. Hi, Jo! I am not familiar with that particular plant, but I will certainly look into it. When referring to estrogenic effects of foods, the key is which estrogen receptors are activated. While some plants may have estrogenic effects, animal estrogens are actual estrogens, and are generally more likely to interfere with human hormones than phytoestrogens (estrogen-like plant compounds), which are not actually estrogens at all. That said, not all phytoestrogens behave the same way in the body. Soy phytoestrogens activate some estrogen receptors in humans, but not all of them. That appears to be the reason for some of the health benefits of minimally processed whole soy foods. Hops, on the other hand, activate different estrogen receptors, and may have harmful effects. You can learn more about phytoestrogens here:
      I hope that helps!

      1. Hi Christine, I’m so grateful to you for researching this, I very much want to eat the plant, and would love to be able to eat something that grows freely in the backyard (I even killed the broccoli sprouts in the kitchen and I’m poor to boot) but I’m concerned.

        Thank you again!!Best wishes!!Jo 


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