Sign up now for Dr. Connealy's inspiring health advice & exclusive offers sent directly to your inbox.

GMOs: The Pros & Cons of Genetically Modified Food

Large GMO Apple Compared to Small Regular Apples
July 9, 2013 (Updated: December 8, 2017)
Leigh Erin Connealy, M.D.

In the past few years, growing research into genetically modified organisms (GMOs) has revealed two ugly truths: GMOs are more widespread than we thought, and they are more harmful than we thought. Further, the vast majority of Americans have been eating GMOs for decades without even knowing about it. I want to bring this new research to you and cut straight through the confusion of GMOs—what GMOs are, what they do, and how to avoid eating them.

What are Genetically Modified Organisms (GMOs)?

The process of genetic modification involves inserting a gene from bacteria or a virus into an organism where it would normally not be found. The purpose is to alter the genetic code in plants and animals to make them more productive or resistant to pests or farming techniques, like being doused with chemicals that would ordinarily kill them. For example, soybeans that have been genetically modified can survive applications of herbicides that would destroy an organic soybean plant.

GMO foods first hit the market in 1996. Since then, most of us have eaten GMOs in many foods, from soybeans, beef, dairy products, corn, beets, sugar, cottonseed, and rapeseed, which is used to make canola oil.

According to the USDA, only 3% of planted acres of corn in 1996 were planted with GMO herbicide-tolerant corn. Today, it’s 89%. In 1996, GMO herbicide-tolerant soybeans were planted in 7.4% of U.S. farm acreage. Today, it’s 94%. Meanwhile, experts estimate that as much as 75% of the processed foods sold in this country contain GMO ingredients. I’m willing to bet that this is even higher.

Pros and Cons of GMOs

On the surface, strengthening soybeans for purposes of more widespread production and consumption seems like a win-win idea. But there are some very real concerns shared by top experts in the health, medical, and nutrition fields. I’ve created the chart below to help clarify some of the pros and cons:

The Pros of GMOs
(according to GMO manufacturers):
The Cons of GMOs
(according to unbiased research):
Growing GMO plants is supposed to allow farmers to:

  1. Spend less money producing more food
  2. Use fewer pesticides and herbicides
  3. Do less tilling to remove weeds, thereby protecting the soil
The downsides of farming with GMOs include:

  1. Creating “super weeds” that have evolved a resistance to glyphosate, a common herbicide in GMO food production
  2. Plants that produce their own insecticide, a bacterial toxin Bacillus thuringiensis (BT), which has led to BT-resistant bugs.
  3. A human population that is unwittingly consuming BT since the insecticide is part of GMO plants.
  4. Disappointing crop yields and doubt over the environmental benefits of reduced tilling.

GMO advocates claim that since many plants already have the ability to produce their own pest repellents, GMO plants engineered to do the same are no different. Wrong! Indeed, Mother Nature did give plants an ability to defend themselves from natural enemies, but we’ve been eating these plants for centuries. As a result, our bodies recognize these substances and are accustomed to dealing with them. But the GMO plant insecticides are new, and research into how our bodies are reacting to them is still new. But studies that have been done so far are showing scary results.

We have been unknowing and unwilling guinea pigs to a massive and dangerous experiment. And study after study shows that pesticides (a term that includes herbicides, insecticides, and fungicides) from GMO plants are linked to cancer, neurological diseases (like Parkinson’s), and a number of other very serious health concerns. They have also been shown to cause cancer in children.

Another problem with GMO crops was discovered earlier this year, when an Oregon farmer found GMO wheat growing in fields where he had not planted it. Although that story is still developing, it appears that other GMO plants have also escaped into the nation’s farmland. If this cross-contamination continues, the consequences could affect the entire food supply.

Latest GMO Research

Also in 2017, the groundbreaking Food Revolution hosted the GMO Revealed Summit. Much of that summit (videos, speakers, information) is available online and I strongly encourage you watch every minute and read every word. It is that good. The panel of experts spoke about everything GMO-related and what it all distilled down to is this:

  • Genetically modified food is not good for you. Period.
  • Genetically modified food is unsustainable and is destroying the planet.
  • Nearly all of the world’s food supply has GMOs in it.
  • Billion-dollar food manufacturers have been hiding these harmful effects from consumers

Today, most people carry a heavy burden of toxins, ranging from plastics to heavy metals to compounds found in drugs and—nowadays—food and beverages. One of my major concerns about GMOs is that they could easily increase our toxic load, leading to even more cancer diagnoses.

New studies on the toxicity of various chemicals used to produce GMO products are not reassuring, either. One recent clinical trial, for example, found that glyphosate, a common herbicide ingredient used to grow GMO plants, caused human breast cancer cells to grow due to its estrogen-like qualities. Glyphosate, I should add, is deemed a carcinogen in California and is the active ingredient in Roundup weed killer products. The World Health Organization hedged slightly, calling glyphosate a “likely carcinogen.”

Get My FREE Curcumin Report

Chronic Inflammation Decoded

Another report from the Journal of the American Medical Association showed that exposure to glyphosate has increased by approximately 500% from 1993 to 2016. Glyphosate is sprayed on “Roundup Ready” crops such as GMO soy, corn, wheat and oats, which are central ingredients in nearly everything in the American diet. Even if you are eating a bread-less hamburger, that cow was likely eating GMO corn, and thus you are too.

While I was not surprised to learn any of this, I still tremble at the thought of the damage that’s already been done and the amount of work that’s needed to fix it. But that’s why I do what I do! And so what follows is everything you need to know about consuming GMOs.

Are GMO Foods Safe?

The answer to that question ranges from “We’re not sure” to “Absolutely not!” Remember, there are millions of dollars spent trying to discredit unbiased research that attempts to show the short-term and long-term effect of GMO foods—not just the effects on our health but also on the environment.

For example, if you search for “GMO foods,” the first search result is a site (I don’t want to dignify it by posting a link) that is funded by The Council of Biotechnology Information, whose members include BASF, Bayer, Dow AgroSciences, DuPont, Monsanto Company and Syngenta. Clearly, they have a vested interest in spreading disinformation.

No wonder so many people are confused about GMO foods. We’ve been lied to for decades by companies that have a financial interest in keeping the truth away from us. And they continue to fund campaigns to distort the truths that are finally bubbling to the surface.

The fact remains that there are no long-term studies demonstrating that GMO foods are healthy. But given the results of studies I’ve seen, I avoid GMO products whenever possible for myself and my family, and I recommend that you do the same.

GMO Food List

It’s safe to assume that it is standard procedure for major food manufacturers (General Mills, Tyson, ConAgra, Coca-Cola, Smithfield, Nestle) to use GMOs in their flagship products. Doing so allows them to produce more food for less, increasing profits and share prices. And they spend those profits lobbying politicians to look the other way as more negative GMO research comes to light but also to develop shady marketing campaigns that discredits people like me who are trying to educate you on the growing health hazards of GMOs.

So I want to tell you right here and now what you need to avoid and what to eat if you want to be GMO free. First, if a food does not say that it’s GMO-free, then it’s safe to assume that it has GMOs in it.

When I buy any of these foods I shop for organic versions, or varieties bearing a “Non GMO” label.

      • Cereal
      • Non-organic dairy products
      • Soy in any form (oil, tofu, protein powder, meat substitutes, etc.)
      • Vegetable oil
      • Salad dressings
      • Granola bars
      • Chicken nuggets
  • Papayas
  • Zucchini
  • Yellow squash
  • Anything containing high fructose corn syrup
  • Bread and crackers
  • Rice
  • Potatoes
  • Tomatoes
  • Peas

But, since the answer affects the health of nearly everyone in the nation, here’s the advice I give my patients:

Eat organic produce, grass-fed beef, free-range poultry, and wild-caught fish whenever possible.

Yes, organic food, which has been grown without chemicals or growth hormones, does tend to cost a little more. But you can either pay a few cents more for organic produce, or you can pay a lot more for doctor visits, prescription medication, and hospital stays. Personally, I prefer to pay a bit extra for the peace of mind that comes with knowing my food is GMO free.

The debate over GMOs in my mind is not even a debate. I know which side is telling the truth. The hard part is putting the truth on food labels. Between now and then, it’s vital that you make informed choices about the foods you eat.


  • Thongprakaisang S, Thiantanawat A, Rangkadilok N, et al. “Glyphosate induces human breast cancer cells growth via estrogen receptors.” Food Chemistry and Toxicology. 2013 June 10.
  • Alavanja MC, Bonner MR. “Occupational pesticide exposures and cancer risk: a review.” Journal of Toxicology and Environmental Health: Part B: Critical Review. 2012;15(4):238-63.
  • Koutros S, Beane Freeman LE, Lubin JH, et al. “Risk of total and aggressive prostate cancer and pesticide use in the Agricultural Health Study.” American Journal of Epidemiology. 2013 Jan 1;177(1):59-74.
  • Roberts JR, Karr CJ. “Pesticide exposure in children.” Pediatrics. 2012 Dec;130(6):e1755-88.
  • Recent Trends in GE Adoption.” USDA. Published July 12, 2017.
  • Weeks, John. “JAMA Report: Exposure to GMO-Associated Glyphosate, a Likely Carcinogen, up 500 Percent.” Published Oct. 26, 2017.

Did You Enjoy This Article?

Sign up to get FREE access to more health tips, latest research, and exclusive offers to help you reach your health and wellness goals!

  • eric malouin

    Jeffrey smith and Dr Akiba Green share some very compelling arguments toward GMO foods. In 1989 37 deaths and 1500 permanently disabled caused by genetically modified tryptophan supplements. The manufacturer Showa Danko settled a lawsuit for $2 billion. In 1996 brazil nut genes were spliced with soya beans to add more protein but some consumers went into amphalatic shock due to nut allergies. Fortunately it was removed from the market before any deaths occurred. The late nineties witnessed the splicing of fish genes into tomatoes. In 2003 the University of Nebraska publshed articles in the journal of immunology identifying allergens with genetically modified corn and soy. Farmworkers working with BT pesticide spray experienced some allergic reactions. A decade long study of GM peas was abandoned when it was discovered that it was causing allergic lung damage in mice. The FDA has already improved salmon gene splicing in soy beans in order for the consumer to get omega 3 fatty acids, thus heightening the risk of an allergic reaction within people who have fish allergies. In 1993 the FDA approved Monsantos RBGH (RBST) a genetically altered growth hormone injected into cows to increase milk yield. This growth hormone is a protein hormone which simulates the pitutiary gland in the cow, however its use increases the growth hormone in Humans called IGF1 from 70% to 1000%. IGF1 is a naturally occurring hormone that stimulates growth in puberty but in excess has adverse effects in adult humans causing excessive cell growth that can turn cancerous, in particular the colon, breast and prostate. This was confirmed by Dr Epstein at the University of Chicago who specifically stated that excess IGF1 levels can induce a malignant transformation of human breast epidilea cells. Despite Monsantos claims that most of the hormone gets destroyed after pasteurization, monsantos own scientists were only able to destroy 19% after boiling the milk ( pasteurization) for 30 minutes but normal pasteurization milk is only boiled for only 15 seconds. Monsanto walked away from this business in 2008. Last month the WHO cancer institute announced that Glyphosate, Monsantos pesticide spray that is sprayed on all GM crops was found to be carcingenic. One of the most damming reports on GMO completed in 1998 by Arpad Pusztai and based on a 3 year study on GM potatoes fed to rats. As a result the rats developed large tumors, stunted their growth and compromised their immune systems. Once the report was published Pusztai position as lead scientist for 35 years was dissolved. In summary there are many controversial studies ‘out there’ and the the biggest human safety study is in process right now..did you volunteer ?

  • hi


  • Guest

    gurl aint nobody got time fo dat puhleez

  • IMtheEggman

    Not sure where or why you come to your conclusion’s but..c’est la vie. Why are you questioning my comment re business, we seem to agree. Your comment re ills by iatrogenic means is way off. Did you just learn the word? Being in a family of higher end health industry workers…the kind that require 6-8 years of university, I showed them your comment and they simply shook theirs heads. Your last paragraph is just plain wrong. you are on the anti-vaccine bandwagon. It is misguided. You choose to take that side which is your prerogative. Anyway, I’ve moved on from this old post. You should too.

  • Stefani Hoffman

    You cant wash off the chemicals, most of them are taken into the plant system in order to work. You might also want to research more, sorry to ruin that for you.

  • Kat

    Wow. Of course business is about money. But business is a trade of which I can make choices. If I want a hammer, there are two hardware stores in my town or I can go online and have other options. I can look up reviews to see which has the best features and meets my needs.

    What the grocers, chemical companies, and other agriculture corporations are working hard not just to make money, but to limit the choices of consumers.

    As for the idea that we are alive today because of pharmaceuticals, that is just ignorant. Most of the chronic ills caused today are iatrogenic. Properly prescribed medicines are among the top killers in this country.

    Contemporary folks seem to have a disdain for previous generations, but the fact is, if you were born 100 years ago and lived until your 5th birthday, the chance of living a long, HEALTHY, active life was better than today. It was the infant mortality rate (which has largely been addressed by better hygiene and water, and better living conditions; most childhood illnesses were not fatal and already greatly reduced BEFORE any vaccine was introduced).

  • Letty Colon

    Best comment. You hit it right on the nail!

  • IMtheEggman

    Really? name one business that isn’t about money. And don’t knock pharma. If it wasn’t for this organization most of writing these comments would have died at some point in our lives. Balance your opinion! It’s too easy to jump on the anti-GMO bandwagon.

  • IMtheEggman

    This is about the fifth site so far that I’ve read in the last hour that either claimed non-bias or noted about a half paragraph of “Pro” and multi-paragraphs or an essay to support “Con”. This is not balanced and clearly leans to the anti-GMO team.

  • ForrestByers

    I don’t know what conclusions to reach from reading this article, so I will try to play ” devil’s advocate”. The article states that the “science” that Monsanto used is biased by the supposed fact of its own self interest. Question, where is the ethical purity of “science”? If it is established by the commonality, that facts are facts, which are universally accepted to be true in all cases, which is supposed to be the backbone of all scientific methodology and inquirement, if this postulate is correct, then the Monsanto science in order for it to be science, must abide by the same rules and therefore is not an issue of political debate, unless of course, it can be shown that Monsanto, somehow through its scientific methodology established supposed facts, that are not “facts” at all, but if this is the case, then other scientists should clearly be able to demonstrate it is not science. I have heard no debate or argument based on demonstrable “facts”. Political posturing and bombast, yes there seemed to be plenty of that, speculation, emotional accusation, yes I acknowledge that, but where exactly is the demonstrable review establishing that Monsanto science is not valid by the establishment that the facts are not true? So far, if this is been “peer review”, the result has more to do with politics and fashion, then relevant facts, that make up the “science”.

  • frank the crank

    did not think that my very scientific link would be allowed to be posted.

  • frank the crank

    i actually wish people before they write articles do some in-depth research. I do not like gmo but it needs to be told truthfully not with lies and innuendos.

  • Adria

    So I went grocery shopping for gmo free and gmo additive free foods haha! 2 small grocery bags! It’s in about every thing. Now I will go back to my youth where we made our own food from scratch. No packaged foods, processed foods, junk foods ( I couldn’t even find a gum to chew without dextrose in it). I remember my mom telling me she was thinking while pregnant with me of taking thalidomide to ease her morning sickness but being so health conscious and against drugs decided against it. Years later wow! GMO OMG years later. Amazing what people will do for convenience as I found myself doing. But now I am starting to get sick so time for health care not sick care. Some don’t care, some don’t believe, some don’t know, but choice should be our right so Just Label It! Fluoride in our water? Take it out! Add it to your own water not every ones. We all have the right to know and choose what goes in our bodies and our children’s bodies. All these diseases increasing and new ones stronger ones coming, growing up was practically unheard of.

  • Adria

    i would like to correct my comment “I do know I would rather eat foods resistant to pests than foods heavily sprayed with insecticides to control the pests.” TO ” I do know I would rather eat foods “naturally” resistant to pests” not GMO altered to or sprayed foods as you can wash them off. Or eat the chemical free pest with my food.”

  • Adria

    GMO’s goal from all my research is MONEY. If we were meant to eat, drink and bathe in man made chemicals it would be no issue. However unless we fight back the pharmaceuticals will control our lives. I would rather eat foods sprayed at least you can wash them off. Even better I would rather eat the pest where no chemicals reside.

  • roundthings

    Very good article. Check the cancer rates from 1995, the year before GMOs were first approved (under Clinton by the way) and now. The increase is alarming.
    And anyone who thinks Democrats are any better than republicans on the issues of GMOs and food safety only need to look at both Clinton’s long involvement with Monsanto and Obama has practically put Monsanto in charge of his administration.
    In fact, Obama is the most anti consumer President in history

  • John

    I am not sure what to make of GMO foods. The article talks about potential allergies. I don’t now if it’s related. I used to be highly allergic to ragweed, making me miserable in August and September The last few years I have had little or no problem. Is it because I am eating GMO foods making me more resistant to ragweed? I don’t know, but it appears to me to be a possibility. I do know I would rather eat foods resistant to pests than foods heavily sprayed with insecticides to control the pests.

  • Barbara Sanders

    wow. you sound like a monsanto emloyee.
    i actually thought this was a well thought out, unbiased attempt to look at the facts of a situation with lots of unknowns, many of them deliberate. maybe you could be more specific about what you see as bias? and explain in what way a reasoned approach = scare tactics?

  • Jack


  • Jack


  • bob


  • Robin MacDonald

    Completely biased and full of scare tactics.

  • Anna

    wonderful article, I needed to hear this.


Get Your FREE Subscription to
Dr. Leigh Erin Connealy's Health News E-letter