Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
17 Oct

Should You Worry About Genetically Modified Food?

A new study came out last month out of France. In it, researchers found that rats on diets consisting of 11%, 22%, and 33% Roundup-resistant genetically modified corn developed far more mammary tumors than control rats on non-GMO corn diets. GMO diet rats died earlier and in greater numbers. Why is this study notable amidst all the other studies that seem to show the safety of GMOs? Well, it’s one of the few long term GMO feeding studies, lasting a full two years, which, to a rat, is the equivalent of 60 of our human years. The other safety studies which found no evidence of toxicity in GM foods tend to last just 90 days, or 15 rat years. In other words, the French study studied rats over the course of an entire lifespan, whereas other studies have looked at rats for a relatively brief snippet of their lives. Cancer generally develops over a lifetime, as you probably know, so this would appear to be more relevant to human health than the shorter trials.

Of course, there has been a huge outcry against the study and its author. Critics have said the sample sizes (ten rats per group of each sex) were too small, but judging from the official guidelines of the Organization for Economic Co-Operation and Development (OECD), which states that oral toxicity experiments using rats must use at least 20 animals per group (10 males and 10 females), the French study was just doing what other GMO studies have done. Even if the sample sizes are inadequate, couldn’t that be rectified by running a longer, larger, later study to attempt to replicate its findings?

Obviously, genetically modified organisms (GMOs) are a testy subject, and people from both sides of the argument make articulate, seemingly logical points about why the other side is completely and utterly wrong. I don’t claim to have the answer either way, but hopefully this post will help you make a decision that works for you.

To date, it’s true that there exists no conclusive hard evidence that GM foods are dangerous to people. There are no human feeding trials, and, because GM foods aren’t labeled (at least in the United States) and people don’t know what they’re eating enough to give an accurate account of their food intake, epidemiological studies on the effects are impossible to conduct. You can’t ask people how often they’ve eaten GM foods over the past ten years if the average person doesn’t even know what GMOs are. There are some animal studies, like the one mentioned above, but there have been mixed results, with some independent studies showing potentially problematic differences in health outcomes between GMOs and non-GMOs, and industry studies showing no significant differences.

Personally, I’m not so worried about a fish gene being put into a tomato, or insect genes in strawberries on their own merits. I’m worried about whether that particular gene codes for the production of a lectin that might harm the person that eats the crop. I’m worried about the amount of Roundup that farmers will therefore spray on the crops, having been given carte blanche to use gallons of the stuff. I’m worried about the Roundup-resistant weeds and Bt-resistant bugs that are popping up in response to all the Roundup being applied and Bt-crops being used. I’m worried about the more toxic herbicides and pesticides being used to take care of these new superweeds and superbugs. Didn’t a wise man once say that “Life finds a way“? Though he was a fictional character talking about the unintended consequences of using frog DNA to “plug” the holes in dinosaur DNA, I think he was right.

A lot of people are worried about the potential of unintended effects to arise. I think John Hagelin said it well in his statement to the EPA:

Numerous eminent molecular biologists recognize that DNA is a complex nonlinear system and that splicing foreign genes into the DNA of a food-yielding organism can cause unpredictable side effects that could harm the health of the human consumer. Yet, the genetic engineering of our food – and the widespread presence of genetically altered foods in American supermarkets – is based on the premise that the effects of gene-splicing are so predictable that all bioengineered foods can be presumed safe unless proven otherwise.

Take a recent example of transgenic modification applied to cassava, a staple starchy tuber for millions (if not billions) of people across the globe. This is the stuff that’s high in cyanide, requires extensive processing to remove said cyanide, and has an extremely paltry protein content (the lowest of all staples foods, in fact). Transgenic insertion of a gene into the plant increased the protein content four-fold and reduced the cyanide content by up to 55%, turning a decent staple into a fantastic, protein-rich one – at least on paper. The increased protein came from a novel chimeric storage protein called zeolin, which was cobbled together using zein (from corn) and phaseolin (from beans, used in “carb blocker” products). For someone who relies on cassava for, well, everything, the increased protein is welcome and perhaps even necessary. But zein (also known as corn gluten) is a prolamine, a type of plant protein that many people have trouble digesting, as well as an herbicide in its own right (PDF). Wheat gluten is another (in)famous prolamine. Phaseolin is a “carb blocker”; it literally reduces your absorption and digestion of glucose. The zeolin may not have the same properties as zein or phaseolin, and even if it did, those properties may be worth it if it’s the best source of protein in the area, but I think this example shows that genetic engineering has the potential to have unintended effects.

Plus there’s a lot of sneaky stuff that makes you go “Hmm…” It’s just circumstantial, sure. There are no smoking guns, but it’s worth considering:

  • Before being allowed to purchase GM seeds, customers (including farmers, scientists, and other researchers) must sign an agreement that limits what they’re allowed to do with them. For instance, customers can’t replicate the genetic alterations – a perfectly reasonable kind of patent protection. These legally-binding end-user agreements also forbid the seeds from being used in independent research, thereby severely limiting independent researchers from conducting any meaningful tests unless they get permission.
  • After a leading bee research firm published results implicating it in colony collapse disorder, Monsanto simply bought the entire company. That’s one way to do it, I suppose.
  • Following previous stints as VP at Monsanto, lawyer for Monsanto, and administrator at the USDA, Michael Taylor, is now the chief commissioner of foods at the FDA. As chief commissioner, Taylor will be protecting all of us from dangerous food.
  • A veritable who’s who of processed food manufacturers and GMO firms are contributing over $25 million to stop CA proposition 37, which will force companies to label foods that contain GMOs. Monsanto has ponied up over $7 million alone.

It certainly brings to mind Gertrude’s famous line from Hamlet, “The lady doth protest too much,” doesn’t it?

At any rate, you can simply avoid GMOs, and sticking to a Primal way of eating gets you most of the way there. After all, the most prevalent GMOs in the United States are:

  • Soybeans – 93% are GM
  • Corn – 86% are GM
  • Sugar beets – 95% are GM
  • Canola – 87% are GM
  • Cotton – 93% are GM
  • Hawaiian papaya – 80% are GM
  • Processed food – In 2003, it was estimated that 70-75% of processed food contained GMOs. That number is probably higher now.
  • Potatoes and alfalfa – Unknown, but at least some are genetically modified.

Almost without exception, the fruits, the vegetables, the nuts and the seeds you come across and which form the foundation of many of your meals and snacks are not GMO. No need to worry about those. If you’re eating processed foods, however, even so called “healthy snacks,” you’ll likely be eating GMOs.

Unless you’re still cooking with canola, sneaking corn tortillas, eating out at places that cook with soybean oil, making papaya smoothies every morning, and losing bets that have you eating articles of clothing made with GMO cotton, you’re avoiding 99% of genetically modified food simply by going Primal. You’re definitely not eating diets consisting of 11% or 22% or 33% GM corn or soy, so I really wouldn’t worry too much about the occasional bite. Stick to organic potatoes when you eat them and you’re golden. Of course, conventionally-raised, grain-fed livestock are eating almost entirely GMO feed, but I’m unaware of any evidence that this affects the health of those who eat their meat and milk (and grass-fed and pastured animal products are healthier, anyway). Anyone know?

Is there a bottom line to all this? A definitive answer? No; not yet.

But I think at the bare minimum, GM foods should be labeled so that people can make decisions about the food they and their families are eating. With so much uncertainty, I think the only fair thing to do is give people a choice in the matter. Not everyone avoids grains and legumes in general, like us.

Well, I hope this was helpful. I’ll probably get criticized from both sides – for not completely and unequivocally condemning GMOs and for failing to pledge my undying support. Not everything has a clear conclusion, though. So it goes.

By all means, though, get it going in the comment section! I want to hear evidence and arguments from both sides. Just try to be respectful, and Grok on!

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. After reading so much about GMO’s, I have to wonder…when the GMO seeds and ground get watered, has anyone done a study on the nearby water supply and the fish? Also, what happens to the birds who used to help the farmer by eating the nearby insects? If there is so much GMO in cotton, are we at risk when we wear clothing made of it?

    It seems to me that GMO food used to be labeled when it first came out years ago. Why isn’t it labeled anymore? That way there wouldn’t be any question or problems with labeling something non GMO.

    Donna wrote on October 19th, 2012
  2. I suggest checking out the Institute for Responsible Technology at
    Jeffrey Smith and his group have linked to several studies and other articles of information. Even talking about reporters and researchers getting fired for talking about the truth. Or research findings that didn’t support what the company (Monsanto) wanted to be shown, i.e. safe GMOs. The law of unintended consequences…there is no true way to predict what gene expressions will be turned on or off and what will truly happen. Man really has limited understanding although he would like to convince one otherwise.

    I’ll stick with organic, pastured and grass-fed as much as possible. The DH and I are in the process of buying a home and have the large freezer (2) lined up and garden space planned in my mind. We also moved south for a longer growing season. So excited!!

    Sandra wrote on October 19th, 2012
  3. Did anyone else post the link to the movie Genetic Roulette yet? If not, it’s free to watch until Nov 6th, and will provide more information.

    Jayne wrote on October 19th, 2012
  4. The food the animal eats does affect he consumer. I have an uncle that is allergic to corn, SEVERE anaphylactic reaction. If he eats beef that has been fed corn he still has a reaction.

    Bronwyn wrote on October 19th, 2012
  5. When you said that you didn’t think milk and meat from GMO fed animals affect the health of those who eat them, I would tend to be wary. I am so gluten sensitive that I can’t eat the meat of grain fed animals (even better quality ones from Whole Foods), or I have gluten problems and the arthritis in my hands gets really bad. So I’m thinking we react more to what animals are fed than it may be thought.

    Linda Myers wrote on October 19th, 2012
  6. Love the Jurassic park reference. :)

    I reread Jurassic Park about a year ago, and Michael Crichton was ranting about GMO’s in the beginning of the book. Jurassic Park was written 22 years ago. Amazing foresight.

    Laura wrote on October 20th, 2012
  7. Do you homework folks. GMO’s are bad news and will result in cascading catastrophic failure in the food supply eventually. There is conclusive evidence much more then just the article cited. Nature took millions of years to create what works for our bodies and there is much more to it then just inserting genes… And GMO’s are far more prolific in our food then most people realize. Also with current law the label organic does not exclude GMO’s from that label.

    Blayne wrote on October 21st, 2012
  8. GMO Food – The Greatest Threat to Health in the History of Western Civilization

    Jeff Smith’s book, Seeds of Deception, compiles 20 years of data on the health risks of genetically modified foods from scientists such as Arpad Pusztai and Trudy Netherwood who reported that feeding GMO food to laboratory animals resulted in thousands of sick, sterile and dead laboratory animals. The greater health issue is the increasing food allergies resulting from consumption of GMO food in the US. While American consumers remain oblivious, GMO Foods have been introduced into the US food supply without safety testing or even labeling. Already 80% of our US food supply is GMO, affecting corn, soy, cotton seed oil and canola oil. Many civilized nations have banned GMO Food. The British Medical Association has asked for a moratorium on GMO foods.

    To

    Jeffrey Dach MD

    Jeffrey Dach wrote on October 21st, 2012
  9. THIS Documentary tells the tale in an easy to understand way..all about GMO’s its well done. Free viewing online thru the end of October, pass it on ! Say NO to GMOS and the criminals who put them on us without our knowledge!

    lori wrote on October 22nd, 2012
  10. Normally I agree with your articles, but not this one. You say that there is no definitive answer that it is harmful… I don’t see any mention in your article about BT Toxin. We are seeing cases, and RCTs demonstrating, that BT Toxin(which they have modified their plants to produce) and which they swore is safe for human consumption and would be fully broken down in the digestive tract is showing up in human blood samples. I don’t have the figure in front of me but I seem to recall it was 70% of women, or 95% of pregnant women. They have also found that it shows up in fetal blood, and that it continues to show up even when all sources of BT Toxin have been removed.

    Not just that but Roundup, BT, and a number of their associated pesticides have been shown to delay apoptosis, damages embryonic kidney cells, causes necrosis…

    I am going to rephrase the conclusion here the way I think it should go.

    Is there a bottom line to all this? A definitive answer? Yes.

    While it may be possible to have GMO foods that benefit humanity or are at least safe, at present all GMO foods must be viewed with, at the very least, extreme caution and skepticism. Until such time as GMOs are not being developped by people out to make money off them, and by people who’s financial interests(and the lack of repercussions) make them inclined to hide all negative evidence, all GMOs are a bad idea.

    Not only that but our understanding, as advanced as it is, is still hugely lacking and this field, like all others, is subject to the law of unintended consequences.

    Are GMO foods bad? Yes.

    James wrote on October 23rd, 2012
  11. See this segment on the potential harm from GMO food. Very fresh perspective.

    Summer wrote on October 24th, 2012
  12. I live in CA where right now they are trying to pass a proposition to label GMO foods. I want to vote for yes for it, but as it is written, I can’t.
    As it’s written all items containing GMOs will be labeled but meat/egg products are EXEMPT from needing to label them as GMO if they are fed or INJECTED with GMO products.
    As this article points out, I can reasonably avoid GMOs by eating Primal but it’s my meat products that I want to know about as well.
    Why is it okay for a Rancher to feed cattle candy to substitute for corn and not have that labeled but every box of Cheerios out there will be stamped with a GMO label?
    I fully agree with a right to know what is in what we are eating, but if we are going to force corporations to label foods they need to label animal products based on what they are fed too.

    StephW wrote on October 24th, 2012
  13. In order for GMO treated crops to be approved a 2 year study on rats would be required. This study would probably be conducted to OECD 453 combined chronic toxicity and carcinogenicity study, which under group size states:

    “For such reasons, each dose group and concurrent control group not intended for earlier sacrifice should contain at least 50 animals of each sex. A high dose satellite group for evaluation of pathology other than neoplasia should contain 20 animals of each sex, while the satellite control group would contain 10 animals of each sex. A moderate increase in group size
    will provide relatively little increase in statistical power of the test. If interim sacrifice(s) are included in the study plan, the initial number should be increased by the number of animals scheduled for the interim sacrifice(s).”

    This means that your statement of 10 rats being a valid group size is misleading. For a 2 year study, at least 50 rats per dose should be allowed the potential to live out the full 2 years of the test. Sample sizes as small as 10 would never be accepted in a 2 year regulatory study. Such groups sizes are only applicable for short term studies, which are another OECD guideline entirely. It is only fair to compare a suitable guideline that covers the duration of the study.

    GMO is a very misunderstood area of science. It is simply doing what breeders have done for decades previously by breeding varieties that have desirable traits. Naturally there will always be some genetic variation. Conventional breeding randomly selects this with no further testing being required. GMO selects traits in a controlled way and significant testing is required.

    I have no affiliation to GMOs nor such testing and I am not saying I would select GMO produce. Living in Europe we do not have significant exposure as you potentially do in the US. However, I feel that the above article is quite heavily biased and does not really give a balanced view. The other side of the coin is would you select something that is genetically modified and not tested (conventional breeding) or genetically modified and is tested (what we refer to as GMOs)?

    Karen wrote on October 24th, 2012
  14. Well done. I suspect that the people now diligently avoiding GMO foods because their gut says that they may be dangerous would have trusted the same instinct to avoid smoking cigarettes before it it was definitively proven that they posed a health risk. You gave an honest and fair appraisal of the known situation with enough information to guide thinking people to a sound conclusion.

    Andrea wrote on October 24th, 2012
  15. I suspect that the people now diligently avoiding GMO foods because their gut tells them they may be dangerous would have trusted the same instinct to avoid smoking cigarettes before it it was definitively proven that they posed a health risk. You gave an honest and fair appraisal of the known situation with enough information to guide thinking people to a sound conclusion.
    Well done.

    Andrea wrote on October 24th, 2012
  16. I always wonder about farmers markets too though… so they make a little sign that says ‘organic’ — isn’t that tempting if they know that’s what people are looking for? Any suggestions? I’m in SoCal…

    Stephen wrote on October 24th, 2012
  17. Mark, stating that there are no conclusive studies that GMO harms humans is the argument the tobacco industry used for decades. Non-industry studies (except Arpad Pusztai’s of course) have repeatedly raised alarming concerns. The numerous countries that outlaw GMO clearly have read these or why else would they resist a profitable enterprise in their countries?

    Considering how GMOs are produced, in addition to the viral vector mentioned in a post above, the piece of DNA inserted is not exact. It is a section that contains the desired gene sequence, along with starter and stopper signals. Anytime the stopper signal does not get in properly the gene sequence produces unknown molecules with unknown consequences – rogue chemicals if you will.

    Ed Castro wrote on October 24th, 2012
  18. Why buy organic? There’s only one Earth. Less about my dinner plate, my health, my pocketbook…More about the health of the dirt all creatures share, the sustaining ocean, the air. And when given a choice, I take a local peach over an organic, trucked strawberry anyday. Recommend Animal, Vegetable, Mineral by Barbara Kingsolver if ya want a good read that’s thoughtful, funny at times and never preachy. Can you be primal AND eat within 100 mi radius? Good challenge, y’all.

    Teresa wrote on October 24th, 2012
  19. I will be starting my own square foot gardens next spring…I will be able to control how my garden grows…and I will be sure to purchase non-gmo seeds and plants. :)
    I guess it all boils down to the little things.
    Oh…I also purchase grass fed/finished meats from local farmers. Definitely worth the extra money!

    Cindy wrote on October 24th, 2012
  20. My comment isn’t about GM but rather about free roaming grass feed cattle vs corn feed cattle which I assume is kept in confined spaces of some sort. I live in NZ so all our cattle is in paddocks so not sure about overseas methods of farming anyway a work colleague of mine raised an issue with grass feed which initially outraged me as I have always been of the opinion that grass feed is better. In NZ we have the issue that because all our cattle are grass feed we have a pretty big water quality problem in alot of our waterways due to cattle effluent and fertilizer run off. He was of the opinion that if we condensed our cattle and corn feed them similar to the states and china we would solve that issue. After thinking about it for a while I concluded it was a fair point although I would hate to see NZ go this way the fact is that our current farming methods are negatively impacting our water ways.

    Jamie wrote on October 24th, 2012
    • Joel Salatin’s book “folks this ain’t normal” covers this nicely, I don’t have a link but the point was: The land use and subsequent damage to the environment for grain fed feed lots is far more devastating then any grass feed operation. You also have to look at how the grass fed operation is managed. Ideally it should be “intensive rotational grassing”. “Intensive” might sound bad but it is attempting to reproduce natural ecosystems that allow for large herds of ruminant animals. An example would be the buffalo herds of the western US. He also goes into how much carbon will be sequestered and general ecological benefits if you follow that rout as well.

      Joseph wrote on October 25th, 2012
  21. Fortunately i live in Thailand and the peasant farms grow all their own food in tiny plots, they are unable in most cases to buy expensive herbicides and all the other shit that is prevalent in the UK. and the US. Here they save seeds and sell their produce in the local markets 10/ 15 small stalls put up at the road side every where.

    Ask them is this organic and they look blank. Ask them have you put any chemicals on this or that to stop weeds and they look blank. How do you control the weeds, pull them up. DO you put any fertilizers on the food you are selling ,yes we pee in a bucket and add water ,that folks is your nitrates. Monsanto will never crack this market. They have more chance of kissing the pope arse on sundays in saint peter’s square Rome. Thank god for peasants.

    ROGER HAZELDINE wrote on October 24th, 2012
  22. Ever heard of survival of the fittest? It takes on a new meaning today – that fitness needs to come via the ability to navigate safely through our toxic new world.

    Be informed, boycott GMO’s until real safety evidence is available and support initiatives like CA Prop 37!

    John wrote on October 24th, 2012
  23. But rats have very different IMMUNE SYSTEMS than humans. I’d be more impressed if the French had used pigs.

    janice wrote on October 24th, 2012
  24. Mark do you eat GMO foods? Go out of your way alittle to get 100% organic food stuff? Either way each of your actions clearly state what you stand for. GMO foods are not for human health, nutrition, longevity or other optimal wellbeing ideal. They are simply for profits and control. If human trials and studies were to be done on humans, which humans should we experiement on? My vote would be to frist study all CEO’s of Monsanto, there family members then all employees at Monsanto or other biotech company. Next would be all Federally appointed officials involving agrobusiness, chemical business, and their families. That would be the experiement. Ah I feel better. I stand for and respect Nature.

    Dan wrote on October 24th, 2012
  25. We recently moved to Catalina Island and my husband, a wonderful gardner, has put in an organic garden using heirloom seeds wherever possible. We gather seaweed to use as fertilizer and a japanese form of composting using food scraps and bacteria and he’s managed to turn the clay soil here into wonderful, organic, dark, rich growing medium. We go to the mainland to get grass fed beef and bison from Whole Foods and are about to start fishing. I’ve eaten organically for all of my adult life and have never trusted to the kindness of strangers, especially where it comes to profit motive. That’s what chemical fertilizers are all about. It’s ruined farmland and water sources and human health. Eat paleo and don’t look back!

    ellen wrote on October 25th, 2012
  26. According to Mr. David Wolf, potatoes are antiviral all the way down to their DNA, which basically means that they cannot be genetically modified at all.

    Amar wrote on November 7th, 2012

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