/ Maggie Koerth-Baker / 8 am Mon, Mar 25 2013
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  • The case of the poison potato

    The case of the poison potato

    The Lenape potato, developed in the 1960s for the snack business, made a damn fine potato chip. Unfortunately, it was also kind of toxic.

    Frying a potato is a tricky proposition. Doing it right isn’t just about your skill as a cook, but also your partner, the potato itself. Waxy potatoes — high in sugar, low in starch — brown a little too easily as the sugar in them is altered by heat. By the time the interior is cooked through, the exterior is burnt to a crisp.

    Good potato chips come from starchy potatoes. But to get just the right chip color — that perfect, buttery golden brown — you have to pay attention to a lot of different factors, from the types of sugar found in the potato, to the internal chemistry that happens as the potato sits in a sack post-harvest.

    In the late 1960s, researchers from the US Department of Agriculture, Penn State University, and the Wise Potato Chip Company teamed up breed a very special potato, which they named the Lenape. More than 30 years later, one of their colleagues still thought fondly of that spud. “Lenape was [wonderful],” Penn State scientist Herb Cole told journalist Nancy Marie Brown in 2003. “It chipped golden.”

    Yes, the Lenape made a damn fine potato chip.

    Unfortunately, it was also kind of toxic.

    Despite an almost boring reputation as the squishy white bread of the plant kingdom, potatoes actually come from somewhat nasty roots. Their closest relatives are innocuous enough. Potatoes have strong genetic ties to tomatoes and eggplants. But their more distant cousins include tobacco, chili peppers, deadly nightshade, and the hallucinatory drug-producing flower, datura.

    This is a phylogenetic family that is ready to throw down, chemically speaking. Called Solanaceae, its members are known for producing a wide variety of nitrogen-rich chemical compounds, called alkaloids. Nicotine is an alkaloid. So are caffeine, cocaine, and a host of other plant-derived chemicals that humans have taken a liking to over the millennia. Depending on the dose, and on the specific compound, alkaloids can have effects ranging from medicinal, to far-out crazy hallucinatory, to deadly.

    Potatoes produce an alkaloid called solanine. All potatoes have it, and it’s a feature, not a bug — at least as far as the potato is concerned. Like a lot of other plant-produced alkaloids, solanine is a natural defense mechanism. It protects the potato from pests. Think of potato blight, the fungus-like disease partly responsible for the Irish Famine of the 19th century. The more solanine a potato contains, the less susceptible it is to blight. When a potato is put into a compromising situation — when it’s young and vulnerable, for instance, or when tubers get uncovered and, thus, more exposed to things that might eat it — solanine production can rev up.

    Those triggers aren’t always the most convenient for the potato’s human predators. A sudden frost, for instance, can stunt the growth of tubers and promote the growth of vines and leaves, which mimics a younger stage of development and is accompanied by higher solanine concentrations. And if you leave potatoes exposed to the sun for too long after harvest, they start reacting as though they just got accidentally uncovered. They turn green and they produce more solanine. This is actually why you’re not supposed to eat green potatoes. Those spuds, and especially their skins, are rich in solanine. How much solanine varies; it might just be enough to make your stomach a little upset. Or, it could lead to serious illness accompanied by vomiting, diarrhea, loss of consciousness, and convulsive twitching. In very rare cases, people who ate green potatoes have even died.

    Poor post-harvest handling was not the problem with the Lenape, however. In 1974, after Lenape potatoes had been recalled from agricultural production and relegated to the status of “breeding material”, the USDA published results of an experiment where they grew Lenape, and five other potato varieties, at 39 locations around the country. They carefully monitored growing and harvesting conditions and then compared the solanine content of all the potatoes.

    The conclusion: Lenape was genetically predisposed towards producing an extraordinarily high amount of solanine, no matter what happened to it during growth and harvest. The average Russet potato, for instance, contained about 8 mg of solanine for every 100 g of potato. Lenape, on the other hand, was closer to 30 mg of toxin for every 100 g of food. That made it nicely resistant to a lot of agricultural pests. But it also explained why some of the people who were the first to eat Lenapes — most of them breeders and other professionals in the agriculture industry — ended up with severe nausea, like a fast-acting stomach bug.

    What makes the Lenape really interesting, though, is its legacy as a cautionary tale. I first learned about it from Fred Gould, an entomologist at North Carolina State University, whom I met while I was working on a New York Times Magazine story about genetically modified mosquitoes.

    He used Lenapes as an example of risk and uncertainty. Often, people frame genetically modified plants as this huge open question — a giant uncertainty, of the sort we’ve never dealt with before. There’s this idea that GM plants are uniquely at risk of producing unexpected side effects, and that we have no way of knowing what those effects would be until average consumers start getting sick, Gould told me. But neither of those things is really true. Conventional breeding, the simple act of crossing one existing plant with another, can produce all sorts of unexpected and dangerous results. One of the reasons Lenape potatoes are so infamous, I later found out, is that they played a big role in shaping how the USDA treats and tests new varieties of conventionally bred food plants today.

    In fact, from Gould’s perspective, there’s actually a lot more risk and uncertainty with conventional breeding, than there is with genetic modification. That’s because, with GM, you’re mucking about with a single gene. There are a lot more genes in play with conventional breeding, and a lot more ways that surprising genetic interactions could come back to haunt you. “You try breeding potatoes for pest resistance, but you’re bringing in a whole chromosome from a wild potato,” he said. “We’ve found interactions between the wild genomes and the cultivated genomes that actually led to potentially poisonous chemicals in the potato.”

    In 2004, a National Academies panel on the unintended health effects of genetic engineering reported that conventional potato breeders continue to try to increase the amount of solanine produced by the leaves and vines of their potato plants in hopes of making those plants more naturally pest-resistant. Because of that, the USDA actually has a recommended limit for solanine content of new potato varieties — but that limit isn’t strictly enforced.

    Gould’s point isn’t that genetic modification is always better than conventional breeding. It’s not. Instead, they’re both tools — imperfect technologies that could produce unintended side effects. Which one you choose to use depends on what you’re trying to do. But, either way, you can’t say that one is scary and one is safe.


    Photo: REUTERS/Hazir Reka
    Mendel In The Kitchen: A Scientist's View Of Genetically Modified Food [Google Books]
    Towards fewer handicapped children [bmj.com]
    Lenape: A new potato variety high in solids and chipping quality [springer.com]
    Safety of Genetically Engineered Foods: Approaches to Assessing Unintended Health Effects [nap.edu]
    Effect of Environment on Glycoalkaloid Content of Six Potato Varieties [Google Books]
    The Potato in the Human Diet [Google Books]
    A Review of Important Facts about Potato Glycoalkaloids [PDF, ucdavis.edu]

    / / COMMENTS

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    1. For those of us who are reluctant (not OPPOSED) to genetic engineering, there are two big issues:
      1) the amazing lack of testing (in animals  and humans) – just like this article points out.
      2) the spread and cross-pollination to other crops as these two stories point out:Right now in the Willamette Valley in Oregon, there is a push to allow Canola to be grown.  “Canola is very invasive and can cross pollinate with many different crops including turnips, broccoli raab, some kales, rutabaga, and possibly radish and broccoli.”(from http://www.friendsoffamilyfarmers.org/?p=1596 )In 2004 it was reported that gentically engineered grass seed was found ~13 miles downwind from a test plot. (http://www.nytimes.com/2004/09/21/business/21grass.html?_r=0 ) That’s the two-fold rub: lack of testing and cross-pollination.

      1. Please don’t think of this as a “YEAH MONSANTO! WOoo!” kind of thing. That’s not how it’s meant. I have beefs with how the agriculture industry is regulated on many different fronts (including GM crops and conventionally bred crops). The point of this is more that it’s not the technology, it’s how it’s used and how we build political and legal frameworks around it. Even something as simple as basic breeding can prove to be dangerous if you’re not paying close attention to the outcomes. 

        1.  I thought you made your point very well, Maggie.  A good essay with a strong real-world example of how much more important testing and monitoring is than the actual production techniques.

           Farmers/corporations who are heavily invested in selective breeding/genetic engineering are not the best judges of what should be eaten, and the reason GM’s more of a nagging problem is regulatory capture by organizations like Monsanto.  Known bad actors are making sure GMOs aren’t labeled, in order to prevent proper monitoring and testing, and they are actually trying to justify this behavior on the grounds that if they properly inform people nobody will buy their product.

        2.  thank you for such a well thought out article.  as a plant biologist i am profoundly dismayed by the way a lack of science literacy makes genetic engineering more dangerous and less profitable. 

        3. I  don’t know you well enough to tell if you are a selective researcher, or if this piece is pure unadulterated spin. Because the crucial information you failed to provide is that this potato was absolutely inedible. Solanine 30mg/100g is bitter and burning of the mouth and throat. The effects of solanine are readily traceable, unlike the endocrine disruptors, teratogens (glyphosate) and immuno-reactive inflammatory agents (bt) which produce chronic, untraceable adverse effects.
          Additionally, you conveniently forgot to mention the 2,4-D, dicamba, and quizalofop crops making their way through the regulatory pipeline, in spite of the risks of increasing ALS, lymphoma and other chronic disorders, which will never be traced back to the food.
          My conclusion: articulate non-science based bullshit dressed up with a ribbon–embarassing, really.

            1. When an individual makes a statement using the word “we” I am tempted to ask ” do you have a mouse in your pocket”, Mary?
              The article I read, I believe,  is trying to blur the distinction between fictional “unpredictability” of conventional breeding and factual unpredictability ( insertional mutagenesis, anyone?) of the currently commercialized genetically modified crops using ballistics and Agrobacterium transformation. The blurring of these lines is obviously not appreciated by Ena.  Neither is the one sided nature of this article, which  focuses on the  trivial  public health implications of the non palatable Lenape while entirely  ignoring the very real public health implications of  tangible crops (the Enlist line) millions could be ingesting, in spite of lack of any safety testing and the mixed science on toxicity of 2,4-D.  
              I expect a  “real” science reporter to dig far and deep to ferret out  relevant science. For example,  Dr. Belinda Martineau, the scientist who conducted the safety studies on the first GE plant, the Flavr Savr tomato (engineered for long shelf life) at Calgene, points out in her book First Fruit: the Creation of the Flavr Savr Tomato and the Birth of Biotech Foods: “Rather than personal opinion, the scientific community should give the public facts, hard facts; the results of studies that indicate these foods are safe to eat and that growing them on a large scale will not cause environmental damage. Scientists and regulators throughout the ag biotech industry agree that more public education about genetic engineering research is necessary, but, thus far, few have provided much information beyond how the technology works and the wondrous things that might be done with it. . . . And simply proclaiming that ‘these foods are safe and there is no scientific evidence to the contrary’ is not the same as saying ‘extensive tests have been conducted and here are the results.’ In fact, without further elaboration, ‘no scientific evidence to the contrary’ could be construed as ‘no scientific evidence, period.’ ”   http://www.amazon.com/First-Fruit-Creation-Tomato-Biotech/dp/0071360565

        1. True.  The dog, after all, is a GM wolf, and wheat is GM grass.  Stone-age genetic engineering, or even renaissance genetic engineering, hardly ever produced toxic food.  But the Lenape potato was a counterexample – note the story takes place in the 1960s.

          The tools we have today are much more powerful.  Farmers in the 60’s couldn’t insert jellyfish genes into their sorghum, and that opens quite a can of worms.  Strong evidence-based oversight might be a good idea, but ADM and Monsanto would never allow that.

          1.  How do we know that stone-age efforts at cultivation didn’t result in toxic food? It might be argued that they wouldn’t think to abandon certain routes that correlated with sickness, but it’s not as if they were any less intelligent than we are today, within reason. I suspect that anything that came up that was particularly troublesome didn’t make it down to when records were more reliably kept, myself.

          1. That’s probably because LotR was partly a pamphlet against modernization and industrialization. The enemy is constantly inventing and creating new things and to Tolkien this could only be for and/or bring evil. Static races like Hobbits and Elves are good, dynamic races like men are evil or, when good, always on the brink of being seduced.
            The message is: change is bad.

      2. Yet another issue is the land grab issue where companies use finding the invasive spread of GE crops to neighboring fields an intellectual property/licensing theft, take small producers to court, and when they can’t pay, take their land to expand agribusiness holdings. It’s a dirty business.

        Also please don’t apologize for the botany with notoriously poisonous solonaecae – the entire belladonna-related family of potato/tomato/pepper/eggplant is prone to bad bits. You can be poisoned by eating the green under a potato skin or, God help you, a dry blackened bit. Europeans refused to eat tomatoes on their introduction from central America, properly seeing them as giant belladonna berries. Food allergies to this family of veggies is very common because some of the chemicals in them are borderline to our digestive systems.

        Get real.

    2. “Waxy potatoes — high in sugar, low in starch”

      I’m confused. Starch *is* sugar.

      Even if “Waxy potatoes” have a different kind of starch, it still ends up as glucose starting the moment it hits your saliva (by amylase). So comparing different kinds of starch seems to me kind of like asking what weights more: a pound of gold or a pound of feathers?

      1.  Starch is a subset of sugars. It is perfectly possible to be high in sugars and lows in starchs.

        A crazy cat lady’s house, for example, might have a large amount of mammalian predators but a low amount of bears.

        1. Starch is a complex sugar; they’re chains of glucose molecules. But the only difference I can find between conventional and waxy potatoes is that they have more of one type of starch over another (different lengths/shapes of glucose chains).  But you’re small intestine cannot tell the difference, as it’s all glucose by then.

          All I can find about waxy potatoes is that they have “less starch and more water”. It seems they just have less starch overall than you average Yukon gold.  Not less starch and more sugar. 

          1. I didn’t say the original statement was correct, or even made sense, just that your argument against it demonstrated a serious flaw in reasoning.

          2. No one’s asking whether your small intestine can tell the difference, the question is whether it browns differently in hot oil.

            1. “Low in sugars” in relation to potato processing has nothing to do with the overall nutritional composition of a product. It means low in (free) reducing sugars (glucose, fructose). This is important because the amount of reducing sugars largely determines the color of the final product

      2. Starch is a carbohydrate, which is very easily broken down to its component sugars as you suggest using acids and/or enzymes, but it isn’t a sugar itself. It reacts and cooks very differently from a sugar.

        1. And so begins the never-ending war between chemist and cooks (cooks, sadly, not realizing they are a subset of chemists).

          1. Since everybody cooks, even if only by proxy (fast food, restaurants, microwavable box-of-carbs), I submit that chemists are a subset of cooks.

            1. The act of mere cooking does not necessarily mean one is allowed to carry the title of “cook”, at least that is what my wife keeps telling me.

      3. I thought everybody knew that a pound of feathers is heavier than a pound of gold!

        Gold is measured in troy pounds and feathers are measured in avoirdupois pounds. Troy pounds have 12 ounces and avoirdupois pounds have 16 ounces. A troy pound contains 372 grams in the metric system and an avoirdupois pound contains 454 grams. 


        Just because something is obvious does not mean it is true.

        1.  But which weighs more, a ton of feathers or a ton of lead? [we couldn’t find enough gold]

      4.  I’m a plant scientist who studies sugar and starch metabolism in maize, which is very similar to potato tubers. Carbohydrates can be stored in the form of simple sugars, disaccharides (2 linked together), or in long chains which we call starch. What matters for chipping quality in potatoes is having the sugars bound up in starch chains rather than existing as free sugars which will turn brown when you fry them in hot oil. So the lenape potatoes had high starch and few free sugars, making them good for chipping. A friend of mine did her graduate thesis work on potato chipping quality, and next to the elevator in my building there is a poster with white and brown potato chips in little baggies that illustrate that difference. How your body breaks down starches and sugars does not matter for how the potato chip behaves when you fry it.
        The breakdown of starch into sugars does start with your saliva, but that does not make starch identical to simple sugars in your body. If you pop an ounce of sugar down your throat, the sugars can be readily and quickly absorbed, leading potentially to a spike in blood sugar. If you pop an ounce of starch down your throat, while it has the same energy content as the sugar, and will eventually end up the same way, it takes time to break it down. Depending on the type of starch, whether long chains of “amylose” or highly branched chains of “amylopectin” it can take a long time or a short time, respectively. This is because we break down the starch on the ends of the chains, and the more branches there are, the more quickly our enzymes can break off the sugar molecules. This is why health authorities suggest that people eat complex carbohydrates, and why some breeders and genetic engineers are working on grain varieties that have more non-branching “amylose” starch, so that the sugars are broken down more slowly, preventing sugar spikes that can be an issue for diabetes and other nutritional issues.

    3. Both of which have always been an issue. It’s not like canola never cross bred with everything in sight under conventional breeding.  All the issues for GM I see are with regards to IP law and corporation asshattery which also has always existed under conventional breeding as well. Seriously, a lot of commercial perennial plants like orchard trees, rose and such are licensed and farmers have to destroy the plant when the license is up and this predates GM breeding.

    4. Googling around I see some people still grow and eat  Lenape potatoes. And I found someone who promotes  glycoalkaloids as beneficial to health.

      1. “I found someone who promotes  glycoalkaloids as beneficial to health”

        One can find all sorts of claims coming from Dr. Internet MD.

    5. Good cautionary tale, but the real issue, as chuckwaugh suggests, is the lack of oversight.  When combined with the widening disparity in scale and resources, the combination of GM and global monopoly produces varieties that are  no longer easily reversed in case of errors.   

      1. The problem of difficult-to-reverse errors overtaking the food supply is a problem that is properly assigned to the existence of monocultures, not to the existence of genetic diversity. Genetically modified plants and animals will occur, whether it is human machinery, viral machinery, sexual machinery or some other type of machinery performing the genetic modifications. In each case, the resulting organisms will either thrive or not, depending on how well-suited they are for their environment. The problem comes from whether they are first successful in causing the destruction / extinction of all other variants, by outcompeting them. That happens almost exclusively in cases of widespread established monocultures – where they have expanded to completely fill a niche or niches.

    6. Speaking of potatoes… a few years back the Executive Director of the Washington State Potatoes Commision was upset at all the bad press potatoes were being given.  So he went on a 2 month all potato diet.  At the end of it, most scientific indices showed that his physical health had improved (there were no pre- and post-diet psychological tests performed).

      His blog of the experience can be found here… http://20potatoesaday.com/

      And a Seattle Times article … http://seattletimes.com/html/localnews/2013545173_potatoguy29m.html

      1.  That might not be any benefit of the potatoes – it may just be the crap he was eating before and was then free of. Besides, it’s fairly well documented that when you start throwing your diet out of whack there are short-term abrupt changes. Not, of course, that you were arguing otherwise, but I’m rather skeptical.

    7. Potato breeding is more unusual than the breeding of many other sorts of plants.  They generally propagate vegetatively; farmers plant cut-up tubers, and the plants grow from the eyes.  The lack of genetic diversity increases the risk of disease, which is one of the factors that drives breeding, i.e. growing new varieties using flowers and seeds.  From what I’ve heard, though, this is *hard* in potatoes.

      Still other foods are often produced by grafting: grapes, most citrus, most apples.  They’re closer to being literal frankencrops: different plants literally cut up and stuck together in different combinations, and the practice goes back centuries.

    8. Wow, I knew about their relation to tomato and nicotine plants, but not Datura. A nauseating potato is one thing, potato + tropane alkaloids; fuuuuuuuuck. Datura is just, well…

    9. I can’t tell if the Lenape potato is full of poisons or if they are just in the skin.

      We peel potatoes because that is how they are eaten in cultures that subsist mainly on them. Eating the skins from several pounds of even “good” potatoes will cause at least gastric distress – so traditional potato eaters fed the peelings to  rabbits which became one of their few sources of concentrated dietary protein.

      1.  Hmm, I always eat the skins unless I’m at a restaurant where they don’t serve them to me.  But then again I’ve never eaten several pounds of potatoes in one sitting.

    10. I think you can get acclimated to the nightshade alkaloids — it’s not just a joke from the Princess Bride.  Besides Ehrlich’s experiments with guinea pigs and really nasty toxins like ricin and abrin, apparently the Hmong use nightshade to make soup and salad (google it, or read Deb Duchon’s account of drinking the soup and its effects http://www.goodeatsfanpage.com/References/TheInterviews/DebDuchon1.htm )

    11. The story of the Lenape potato is a bit out of context.  It is a story of a *known* hazard that was not properly managed. The tip off was the bitter taste.  I have not seen any documentation that folks ate Lenape and had stomach issues as a consequence.  Regardless, there is now an expectation that known hazards be monitored in any type of breeding program, whether biotech or otherwise.

      The problem with GMOs is not about known hazards, which are after all, comparatively easy to monitor.  The vast majority of the expense and testing is to find evidence of unknown hazards– new problems that materialize during the engineering process.  These have thus far failed to materialize. Nor, has anyone been able to articulate to me why inserting DNA in the form of a transgene can originate unknown hazards unrelated to the transgene, while things like mutagenesis or DNA insertions from transposons does not.

    12. I have a food intolerance to everything in the nightshade family. I react as though I have IBS for a few days after the smallest amount. I’m glad this potato didn’t get into the food chain before I realized what was causing my problem, and I hope science carries the day in the GMO debate. It’s a small hope, I must say.

    13. Celery is seldom far from being toxic when you breed it. Cucumbers and zucchini and related family members are prone to similar issues. Savvy farmers save seed from the more robust individuals for future crops. When subject to increased predation cucurbits react by producing their own insecticide, Cucurbitacinin. This occurs more in organic production as farmers inadvertently select for the plants that produce higher and higher levels of Cucurbitacin. The compounds tends to be produced when the plants are stressed such as heat spells. Otherwise they tend not not to. Persons consuming cucurbits with higher levels of Cucurbitacin do react adversely to it as if they had ingested a conventional pesticide. Not suprisingly, this compound is available as a pesticide product.

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