Posts Tagged science

Diet, Nutrition, Cancer, and Sloppy Journalism

Michael Pollan argues in In Defense of Food that the Dietary Goals for the United States, compiled by Senator George McGovern’s Senate Select Committee on Nutrition and Human Needs, ushered in an era in which dietary guidelines focused on nutrients to the exclusion of whole foods. He explains that McGovern’s committee initially recommended a reduction in red meat and dairy consumption before the interested lobbies complained. The result was a compromise, urging Americans to “choose meats, poultry, and fish that will reduce saturated fat intake.”

Pollan explains the significance of the change,

First, notice that the stark message to “eat less” of a particular food–in this case meat–had been deep-sixed; don’t look for it ever again in any official U.S. government dietary pronouncement. (24)

As evidence of this last point, Pollan trots out the National Academy of Sciences’ 1982 report Diet, Nutrition, and Cancer. He tells us,

The lesson of the McGovern fiasco was quickly absorbed by all who would pronounce on the American diet. When a few years later the National Academy of Sciences looked into the question of diet and cancer, it was careful to frame its recommendations nutrient by nutrient rather than food by food, to avoid offending any powerful interests. (25)

He further notes, “With each of its chapters focused on a single nutrient, the final draft of the National Academy of Sciences report, Diet, Nutrition and Cancer framed its recommendations in terms of saturated fats and antioxidants rather than beef and broccoli” (26).

After a few minutes of skimming the report, I couldn’t help but wonder whether Pollan and I had looked at the same document. He is correct to point out that the recommendations referenced fat, rather than meat. He’s not quite correct to say that each chapter focuses on a single nutrient. Some of the chapters discuss multiple nutrients (for instance, Chapter 10, titled “Minerals,” discusses selenium, zinc, iron, copper, iodine, molybdenum, cadmium, arsenic and lead), but on that point he’s close enough for me.

Where Pollan misses the mark badly is in failing to note that the report’s recommendations weren’t found in these nutrient-focused chapters. These chapters summarized the existing science on the various nutrients, without saying what we should do about it. The report did include a section called “Interim Dietary Guidelines,” but this was found in the report’s Executive Summary. Summarized, the guidelines were as follows:

  1. “The Committee recommends that the consumption of both saturated and unsaturated fats be reduced in the average U.S. diet.”
  2. “The committee emphasizes the importance of including fruits, vegetables, and whole grain cereal products in the daily diet…Results of laboratory experiments have supported these findings in tests of individual nutritive and nonnutritive constituents of fruits (especially citrus fruits) and vegetables (especially carotene-rich and cruciferous vegetables).”
  3. “[T]he committee recommends that the consumption of food preserved by salt-curing (including salt-pickling) or smoking be minimized.”
  4. “The committee recommends that efforts continue to be made to minimize contamination of foods with carcinogens from any source. Where such contaminants are unavoidable, permissible levels should continue to be established and food supply monitored to assure that such levels are not exceeded. Furthermore, intentional additives (direct and indirect) should continue to be evaluated for carcinogenic activity before they are approved for use in the food supply.”
  5. “The committee suggests that further efforts be made to identify mutagens in food and to expedite testing for their carcinogenicity. Where feasible and prudent, mutagens should be removed or their concentration minimized when this can be accomplished without jeopardizing the nutritive value of foods or introducing other potentially hazardous substances into the diet.”
  6. “[T]he committee recommends that if alcoholic beverages are consumed, it be done in moderation.”

Thus, of the six interim guidelines, only one was expressed in terms of nutrients, two phrased their recommendations in terms of foods (one of those even recommended eating less of something!), two were seemingly commonsense encouragements to keep dangerous substances out of the food supply, and one was a reminder not to drink too much.

Although the recommendation pertaining to vegetables did briefly mention carotenes, the committee included a clarification between the second and third guidelines:

These recommendations apply only to foods as sources of nutrients–not to dietary supplements of individual nutrients. The vast literature examined in this report focuses on the relationship between the consumption of foods and the incidence of cancer in human populations. In contrast there, is very little information on the effects of various levels of individual nutrients on the risk of cancer in humans. Therefore, the committee is unable to predict the health effects of high and potentially toxic doses of isolated nutrients consumed in the form of supplements.

They were serious about this point, too. In his critique of reductionism (which Pollan quotes), T. Colin Campbell (a co-author of the report) wrote that the Federal Trade Commission sued General Nutrition Centers for using the report’s guidelines to advertise supplements.

Although Pollan has argued that nutrition science “knows much less than it cares to admit” (14), the report shows that the science admits its limits more than Pollan cares to admit. The lack of recommendations on so many of the nutrients considered is an implicit acknowledgment of the lack of evidence. Reading the chapters focusing on the various nutrients, one sees the point made more explicitly. For instance, the researchers wrote in the conclusion of their section on selenium, “firm conclusions cannot be drawn on the basis of the present limited evidence.”

As for those chapters on nutrients, one finds plenty of references to whole foods there, too. For instance, though Pollan writes, “The language of the final report highlighted the benefits of the antioxidants in vegetables rather than the vegetables themselves” (26), the report’s summary of the epidemiological evidence on vitamin A reads,

A growing accumulation of epidemiological evidence indicates that there is an inverse relationship between the risk of cancer and consumption of foods containing vitamin A (e.g., liver) or its precursors (e.g., some carotenoids in dark green and deep yellow vegetables). Most of the data, however, do not show whether the effects are due to carotenoids, to vitamin A itself, or to some other constituents of these foods.

Of course, none of this is directly relevant to the question of how much we can learn about human nutrition by studying nutrients (instead of foods), and it’s on that question that Pollan seems to make his main argument. However, what we can observe here is a pattern of misrepresenting the claims that science has made. This, of course, is helpful to somebody trying to discredit a scientific discipline. But it should be much less helpful if Pollan wants to convince the reader that he is a careful researcher and a credible source of information.

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Science, culture, and nutrient deficiencies

Michael Pollan writes in the first chapter of In Defense of Food,

Vitamins did a lot for the prestige of nutritional science. These special molecules, which at first were isolated from foods and then later synthesized in a laboratory, could cure people of nutritional deficiencies such as scurvy or beriberi almost overnight in a convincing demonstration of reductive chemistry’s power. (21)

Pollan doesn’t dwell on the topic of nutrient deficiencies, but I will. In their article “In Defense of Food Science,” David Julian McClements, César Vega, Anne E. McBride, and Eric Andrew Decker point out that fortified foods have played important role in alleviating a number of diseases, namely pellagra, spinal tube defects, beriberi, goiter, and rickets.

The example of beriberi, which is detailed in Kenneth J. Carpenter’s book Beriberi, White Rice, and Vitamin B: A Disease, A Cause, and a Cure, is particularly instructive. Beriberi, which is often fatal when left untreated, was so prevalent in late nineteenth century Japan that one western doctor dubbed it “the national disease of Japan.” Moreover, western doctors visiting Japan after the Perry Expedition brought about the country’s opening to the West in 1854 found evidence that the disease had been around for a long time.

In the late 1800s, it was determined that beriberi was diet-related, and shortly thereafter it was discovered that beriberi was caused by a deficiency of the nutrient now known as thiamine (vitamin B1). In the case of the Japanese sufferers of beriberi, the thiamine deficiency was related to a diet based heavily on white rice. Although rice naturally contains thiamine, most of that thiamine is found in the husk, which is removed to produce white rice. Carpenter explains the preference for white rice, “In practice, nearly everyone who eats rice as their staple food, that is, the centerpiece for each of their daily meals, prefers white rice if it is available, and eating it can be a status symbol.”

Thus, the example of white rice is one in which longstanding cultural preferences resulted in dietary patterns that were demonstrably unhealthy. This should be reason to doubt an argument Pollan will make later, that the continued existence of a diet is proof of its healthfulness. Furthermore, the subsequent success of nutrition science in curing beriberi shows that science can help improve on a diet that tradition recommends.

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In defense of expertise

Michael Pollan writes in In Defense of Food,

[I]t does seem to me a symptom of our present confusion about food that people feel the need to consult a journalist, or for that matter a nutritionist or doctor or government food pyramid, on so basic a question about the conduct of our everyday lives as humans. I mean, what other animal needs professional help in deciding what it should eat? (2)

Pollan is, of course, correct to point out that no other species consults experts in deciding what to eat, but this is hardly the only way in which our lives are different from those of other animal species. Some differences–say, replacing candle light with incandescent and later fluorescent lighting–probably don’t heavily influence our dietary needs. Others, such as our tendency to live longer lives and spend more time sitting than our ancestors, seem more likely to factor into our nutritional needs.

That isn’t to say that experts will never give bad advice. However, the idea that Pollan hints at here — that it’s strangely unnatural to seek professional dietary advice — deserves to be placed into context. There are many things that are unnatural about our lives. I’d guess that most of us (at least, most people who are reading this) are far enough removed from nature that if we wanted to eat a “natural” diet, we’d have to consult an expert just to figure out what that even meant.

In spite of Pollan’s appeal to the rest of the animal kingdom, a few sentences later he makes it clear that he’s really lamenting the decline of food culture. This is a surprising turn, considering that so many aspects of food culture are also unique to humans. One wonders if Pollan knows of other animal species that cook their food or have the “[d]eep cultural taboos against gluttony” which Pollan mentioned in The Omnivore’s Dilemma. If not, then his appeal to nature does not seem to fit with his argument.

As for culture, I won’t deny that it can teach us a few things. But it happens that our lives are not only increasingly unnatural, but increasingly different from those of our relatively recent ancestors. It’s not obvious that the diet our ancestors ate will work for our more sedentary lifestyles. For that matter, Pollan tends (as I’ll write about soon) to overstate the extent to which traditional diets have really worked for people. It’s perfectly reasonable to ask whether we can do better, and if we’re going to ask the question, I hope the answer will be based on a careful look at the available evidence.

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Beginning “In Defense of Food”

I will soon commence my third reading of In Defense of Food, and this time I’ll be blogging it. I haven’t exactly decided how much I’ll say. It won’t be a daily thing, but I’ll aim for a couple of posts a week.

For now, here are a few pieces of criticism which I’ve found interesting:

  • Daniel Engber critiques “Unhappy Meals,” the New York Times Magazine piece that grew into In Defense of Food. He argues, “Modern nutrition may be more of an ideology than a science, but so is Pollan’s nutritional Darwinism.”
  • Registered Dietitian Ginny Messina writes,

    But for the most part, Pollan’s reasoning about nutrition and research was pretty unsophisticated and uninformed. He carefully describes all of the reasons why nutrition research is flawed, and then employs some of the worst examples of research (animal studies and completely uncontrolled observational approaches) to support his own arguments. He quotes “nutrition professionals” whose credentials and opinions are questionable at best. Almost without exception, his observations on nutrition are wrong—sometimes subtly so, sometimes overtly so, and sometimes in ways that are actually dangerous.

    Pollan defends his right to provide nutrition advice because he speaks on the authority of “tradition and common sense.” But, tradition and common sense will get you about 90% of the way to a healthy diet. The other 10% can have devastating effects and Pollan really has no sense of this.

  • James McWilliams argues,

    Every book is allowed an inconsistency or two. But In Defense of Food contains so many logical contradictions that it eventually leaves the impression of having been cobbled together in a mad rush to meet a publication deadline. Pollan laments on page 9 that “we are becoming a nation of orthorexics: people with an unhealthy obsession with healthy eating.” But by page 186, as if lacking a culinary care in the world, “we” are consuming calories “found in convenience food-snacks, microwavable entrees, soft drinks, and packaged food of all kinds-which happens to be the source of most of the 300 or so calories Americans have added to their daily diet since 1980.” Suddenly, and without explanation, a nation of obsessive nutrient-counting orthorexics has become a nation of careless, Twinkie-gorging anti-orthorexics.

  • If you have institutional access, food scientists David Julian McClements, César Vega, Anne E. McBride, and Eric Andrew Decker took to the pages of Gastronomica last summer to defend their profession in an article titled “In Defense of Food Science.” They argue, “Pollan’s rules are closer to clever catchprases that advocate a particular point of view rather than offering genuinely practical advice.” They go on to write,

    We…propose that foods be judged on the basis of their final relevant attributes (e.g., quality, nutritional profile, and environmental responsibility), rather than strictly on how they are produced (e.g., at home or in a factory). Although it is generally assumed that homemade foods are better than processed foods, this is not necessarily true. Homemade croissants, cakes, or french fries, may be free of additives, but the nutritional consequences of eating them are similar to those of their factory–or restaurant–produced counterparts. We therefore encourage food activists to advocate not only for high-quality fresh foods, but also for the development of more responsible processed foods.

Also, I’m introducing a new comments policy which delineates which kinds of comments are allowed and which I’ll respond to. In short, so long as you’re civil and stay on topic, you should be fine.

Update (1/18): In the comments, Signe Rousseau reminds me of food scientist Gregory R. Ziegler’s piece criticizing Pollan for “selective use of science to support his opinions.” I might as well also mention that I’ve previously blogged Julie Guthman’s criticisms, as well as a few of my own.

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Science Friday’s Carl Flatow: Is Michael Pollan Anti-Science?

Over at The Science Friday Blog, Carl Flatow writes,

Readers of this blog know that I have been inspired by Michael Pollan’s work. I have read all of his books, learned a lot of useful information and cheered him on as he directed the national conversation in a more healthful direction.

About two years ago while listening to Michael speaking on a local radio talk show I cringed as he declared that scientists were to blame our problems. I quickly emailed Michael to protest that the problem wasn’t the scientists. In his brief reply he agreed that I was right.

Last night on national TV, about halfway through his conversation with Stephen Colbert, he did it again. As he began to frame the problem he said, “…we’ve been listening to scientists for too long and they really have misled us….” I beg to differ!

It is unlikely to surprise readers of this blog that I often find Pollan’s treatment of science to be problematic. Indeed, when I watched the Colbert Report interview last week, I initially decided that the line Flatow quotes was far more innocent than the bits of Pollan’s work that I quoted in my Berkeley Science Review piece in September. Until I found Flatow’s piece I wasn’t planning to blog the Colbert Report interview.

Flatow’s title asks, “Is Michael Pollan Anti-Science?” I don’t think it’s quite that simple. Pollan seems perfectly happy to use science, so long as it supports the general thrust of his work. In both The Omnivore’s Dilemma and In Defense of Food, Pollan cites a number of scientific studies, conceding in the latter work that science is “the sharpest experimental and explanatory tool we have.” Scientific studies have been known to appear on Pollan’s Twitter feed, too. But sometimes he’ll use dubious science to make his case; other times he’ll argue against science. It all makes for an argument that is a bit confused, to say the least.

Flatow goes on to explain the work of scientists, whom he contrasts with marketers:

People who are trying to sell us something, on the other hand, often mislead us. In that case (their mission is not to find conclusions on which we can reasonably agree) their mission is to take as much from us as they can before we realize we’ve been cheated.

Michael, PLEASE stop confusing scientists with marketers, you’re stepping on your own great message.

I’m not holding my breath on that one. Moreover, I disagree that Pollan is “stepping on” his message. The vilification of science is a part of Pollan’s message. That’s not to say that a food reform message needs to blame science, but that Pollan does it enough that I have to believe that he very much means it as a part of his message.

Flatow’s point about “people who are trying to sell us something” is an important one, perhaps more so than he intended. Michael Pollan didn’t appear on The Colbert Report just because he couldn’t think of anything else to do that night. He went on the show because he was trying to sell copies of the new edition of Food Rules. The message that science-based dietary advice is responsible for our public health crisis is part of the appeal of Pollan’s books; people like being told that they don’t have to listen to experts.

I can only hope that Flatow’s piece will mark a turning point, and that science-minded people in positions of influence will start pushing back against the anti-science message and scientific misinformation that is all too common in Pollan’s work.

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How Michael Pollan misrepresents science

A couple of months ago, I was invited to write a piece on Michael Pollan’s treatment of science for the blog of The Berkeley Science Review,  a UC Berkeley graduate student publication dedicated to writing about science for scientists and non-scientists alike. As it happened, it took me a while to find the time to write anything, but my piece addressing both The Omnivore’s Dilemma and In Defense of Food just been published.

The first half, addressing The Omnivore’s Dilemma, won’t be anything new for readers who are familiar with my post on Pollan’s reading of Sir Albert Howard’s An Agricultural Testament. Parts of the new post are borrowed directly from that post’s argument that Pollan misrepresents Howard’s work and misunderstands what science is.

The second half of the piece addresses In Defense of Food, and is brand new.  The focus, naturally, is on Pollan’s treatment of nutritionism. Here’s an excerpt:

Pollan quotes a 2001 critical review stating that “the low-fat campaign has been based on little scientific evidence.” Without bothering to explain how nutritionism might be discredited by the failure of a public health campaign that wasn’t supported by science, Pollan presents an alternative theory and its implications for the low-fat advice:

The theory is that refined carbohydrates interfere with insulin metabolism in ways that increase hunger and promote overeating and fat storage in the body…If this is true, then there is no escaping the conclusion that the dietary advice enshrined not only in the McGovern “Goals” but also in the National Academy of Sciences report, the dietary guidelines of the American Heart Association and the American Cancer Society and the U.S. food pyramid bears direct responsibility for creating the public health crisis that now confronts us.

This passage implies that the various dietary guidelines that supported the low-fat movement encouraged Americans to compensate for the reduction in calories from fat by eating more white flour and high-fructose corn syrup. However, McGovern’s Goals called for a substantial reduction in sugar consumption and an increase in consumption of carbohydrates from fruits, vegetables, and grains. Americans increased their sugar consumption and disregarded a recommended decrease in daily energy intake. Incredibly, on the basis of their having followed the recommendation to decrease the percentage of calories consumed in the form of fat, Pollan has declared the Goals not merely unhelpful but directly responsible for the current public health crisis. (This is, to say the least, a surprising departure from Pollan’s explanation of the same crisis in The Omnivore’s Dilemma: “When food is abundant and cheap, people will eat more of it and get fat.”)

(This quote has been updated to reflect a correction.)

I’ll admit that the first time I read In Defense of Food, I mostly enjoyed it, but the second time through, I attempted a closer read and found myself thoroughly disappointed. In the Berkeley Science Review piece, I really only scratched the surface of what’s wrong with its treatment of science. While I’ve come to believe that the work needs a more thorough critique like the one I gave to The Omnivore’s Dilemma, I’ll have to weigh it against various other time-consuming projects (including a number of other writing projects).

If Pollan’s science writings are highly regarded, I can only think that this situation speaks to a need for people with strong scientific backgrounds to communicate effectively with the broader public about science. In that respect, The Berkeley Science Review is a great publication. I encourage you to take a look around their site and subscribe to their RSS feed. Most of their posts are a lot more fun than mine, I promise.

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My letter to Michael Pollan

I just sent a letter to Michael Pollan. I submitted it through the contact form on his website. Here is the text of that letter. I’ve added proper formatting since the comment form doesn’t support it, but it is otherwise unchanged.

Dear Professor Pollan,

A little more than two months ago, I was dismayed to read a claim you made in the New York Review of Books: “Animal rights advocates occasionally pick fights with sustainable meat producers (such as Joel Salatin), as Jonathan Safran Foer does in his recent vegetarian polemic, Eating Animals.” When I read this, I couldn’t help but think that you hadn’t given Foer’s book more than a cursory glance. I think that if you had given the book a more careful reading, you would have seen that Foer was much more respectful than you give him credit for.

The book’s only mention of Joel Salatin is in a lengthy quote by Frank Reese. It’s true that this mention isn’t flattering, but Foer doesn’t endorse Reese’s criticisms of Salatin. Concerning sustainable farmers, Foer writes, “Paul [Willis], Bill [Niman], Nicolette [Hahn Niman], and most of all Frank [Reese] are not only good people, but extraordinary people. They should be among the people a president consults when selecting a secretary of agriculture. Their farms are what I want our elected officials to strive to create and our economy to support.” Is this your idea of fighting words?

I hope that you will take the time to read Eating Animals, now that you’ve written what was ostensibly a review of it. In fact, since I pass North Gate Hall daily, I’d like to offer to lend you my copy.

Your article in the New York Review of Books inspired me to take the rather unusual step of starting a blog devoted entirely to criticism of your work. I wrote about your comment on Eating Animals in more detail at http://wp.me/pW3bH-6. You can also find a properly formatted copy of this letter at http://wp.me/pW3bH-bi.

I think that your comments about Jonathan Safran Foer both in the New York Review of Books and in your April interview with The Huffington Post reflect a tendency to assume that any vegetarian who criticizes your work is an “animal-rights purist” who won’t be content until you unconditionally condemn meat-eating. I won’t deny that these purists exist, but I think that there are many vegetarians who are frustrated because they feel that your treatment of vegetarianism has sometimes been distorted and disrespectful. Moreover, I would argue that your mention of Eating Animals in the New York Review of Books was both of those things.

Over the last two months, I have completed a thorough reading of The Omnivore’s Dilemma, and I have blogged about numerous factual errors, misrepresentations of sources, and weak arguments contained therein. These are not restricted to the topic of meat-eating, and many of them are science-related.

One objection that I have raised that relates to both science and meat-eating comes in your chapter titled “The Vegan Utopia” when you write that the vegan food chain would be more dependent on chemical fertilizer than the current food chain because “fertility–in the form of manures–would be in short supply.” On the face of it, this is a rather dubious claim because we’d need to grow considerably less grain than we do now.

I think it’s also worth looking at the nutrient issue a different way. Any time we use a piece of land to grow food, we remove some nutrients from that land, whether that food be a plant or an animal. Unlike most animals, though, we don’t tend to return most of those nutrients to the land when we’re done with them. Instead, we quite literally flush them down the toilet. If we take enough food from our plot of land, that land is liable to run out of some nutrient eventually, unless we somehow replenish its nutrients. It’s worth pointing out that animals are not a source of the biologically-available nitrogen that is so often limiting. There’s plenty of nitrogen in animal manure, but because the animals on a farm don’t fix nitrogen, they have to get it from food sources. In particular, this means that animals aren’t going to leave more nitrogen on the land than they eat off of it.

In the absence of chemical fertilizers, the job of replenishing nitrogen necessarily goes to the nitrogen-fixing bacteria in the roots of leguminous plants. Animals can certainly help to divert some nitrogen off of pastures and into our food supply. It’s possible that grazing might even increase the rate of nitrogen fixation by these bacteria, although I wasn’t able to find any evidence of this in the literature. In any case, I think it’s quite significant that even at Polyface Farm, the clover and other legumes growing in the pasture are not sufficient to replenish the nitrogen that’s removed in food. Although you write that “The chief reason Polyface Farm is completely self-sufficient in nitrogen is that a chicken, defecating copiously, pays a visit to virtually every square foot of it at several points during the season,” it simply isn’t the case that Polyface Farm is completely self-sufficient in nitrogen. The nitrogen in a chicken’s manure comes from feed, and most of that is grain from off the farm.

In The Omnivore’s Dilemma, you trivialize that input, writing that Polyface meat looks “an awful lot like the proverbially unattainable free lunch.” I don’t think the amount of feed is trivial at all. In fact, using data from The Omnivore’s Dilemma, Pastured Poultry Profit$, and some calorie data, I did a rough calculation (available at http://wp.me/pW3bH-9H) that suggested that the grain in the broiler feed contains forty percent more calories than the farm’s output.

I understand that this calculation is back-of-the-envelope quality. Certainly, if you have done (or seen) a more accurate calculation, I would be interested in looking at it. However, I’ve tried to choose numbers that would favor Polyface. Furthermore, I have not even accounted for the feed for the layer hens, the turkeys or the pigs.

This raises the question of whether it might be more efficient to simply grow grain to feed people. I’m sure that the inputs required to grow feed grains are not the same as would be used to grow human-edible grains, but I think this at least shows that there’s a calculation worth doing and that the Polyface meal probably isn’t as close to a “free lunch” as a reader is led to believe.

I have to think that if it would indeed be more efficient to simply grow food-grade crops, the environmental case for eating meat from farms like Polyface would be much weaker than you make it out to be. As nice as it might be to talk about putting animals on a farm so that the farm resembles an ecosystem, it becomes much less compelling if that farm merely outsources its environmental degradation to a grain farm down the road.

Returning specifically to the subject of nutrients, I think it confuses matters to say that we need animals on farms to “complete the nutrient cycle,” as your website does. That suggests that animals return to the farm the nutrients that we have removed. As the example of the Polyface broiler feed shows, they don’t eliminate the need for outside inputs. They might allow for seemingly more benign inputs (feed versus chemical fertilizer), but we should be mindful of the cost of producing those inputs. (If completing the nutrient cycle is your goal, the natural approach would be using human manure for fertility.)

On a different subject, I couldn’t help but notice that in The Omnivore’s Dilemma, you don’t mention a single thing you ate in your time as a vegetarian. This was a particularly glaring omission in a book that described at least ten meat-based meals (four in exquisite detail). Even this January, nearly two years after you began advising people to eat mostly plants, the meals you consumed over five days (as reported in Grub Street New York) were remarkably low on plant proteins.

I think you might be a more effective advocate for a diet of “mostly plants” if you talked about more of the plant-based foods you eat. There is a certain strain of foodie culture that sees plant-based cuisine as inferior. I can’t help but think that such attitudes are reinforced when the most prominent advocate for eating “mostly plants” doesn’t find many plant foods worth talking about. Aside from that, many people simply don’t know what to eat other than meat. (Perhaps you have a memory from your time as a vegetarian of telling somebody you didn’t eat meat and hearing in response, “Then what do you eat?” or “Where do you get your protein?”)

With that in mind, I wanted to offer to introduce you to some of the plant-based cuisine in the area. There are a number of restaurants in the area that specialize in fine plant-based foods made from local and sustainable ingredients (and no meat substitutes or highly processed foods). I’d like to invite you to join me for a meal at one of these places. I’m not looking to start a conversation on animal ethics; I suspect that’s a matter on which we’ll have to agree to disagree. However, I do believe there is a conversation to be had here on such topics as vegetarians, science, and plant-based food. Let me know if you accept, and we can discuss a time and location.

I understand that this letter (and my blog) may come across as a hostile gesture, but I really don’t mean it that way. I do very much appreciate the work you do to remind people that their food comes from somewhere. However, I think that when we discuss the food options that are available to us, we should do so in a balanced and accurate way, and I have felt the need to speak up where that could have been done better.

I am interested to know what you think about all of this. In particular, if you feel that I have misrepresented your work in any way, I hope you will let me know.

Sincerely,
Adam Merberg

P.S. I plan to post our correspondence to my blog, with the exception of any information pertaining to the time and location of any meeting between us. Please let me know if you prefer that anything else remain off the record.

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The Omnivore’s Dilemma: My Review

When I read Michael Pollan’s The Omnivore’s Dilemma for the first time two summers ago, I was taken aback by a relatively innocent passage in his section on the Supermarket Pastoral food chain:

Taken as a whole, the story on offer in Whole Foods is a pastoral narrative in which farm animals live much as they did in the books we read as children, and our fruits and vegetables grow on well-composted soils on small farms much like Joel Salatin’s. “Organic” on the label conjures up a rich narrative, even if it is the consumer who fills in most of the details, supplying the hero (American Family Farmer), the villain (Agribusinessman), and the literary genre, which I’ve come to think of as Supermarket Pastoral. By now we may know better than to believe this too simple story, but not much better, and the grocery store poets do everything they can to encourage us in our willing suspension of disbelief. (137)

I had certainly never looked at organic food this way. I grew up eating organic food, my parents having discovered organics several years before the US Department of Agriculture began its certification program. When I asked what this word “organic” meant, my mother told me very simply that it meant the food was grown without pesticides. Over the years, I had to tweak that definition for such considerations as chemical fertilizer, but that was pretty much what I thought of when I saw foods labeled organic. I saw no “rich narrative,” no “well-composted soils on small farms,” and no heroes or villains. Nor did I see any reason to be surprised (as Pollan was) by a microwaveable organic TV dinner. That’s not to say that I was born with a detailed understanding of the workings of organic farming. I knew next to nothing about farming, but I never saw any reason to fill in the blanks with these kinds of stories.

I suspect that Pollan is right that Whole Foods would like us to think of these stories. Regardless, I’d venture to guess that he and I experience shopping at Whole Foods about as differently as two people might experience the same grocery store, given his fascination with stories and my own devout literalism.

Having been through The Omnivore’s Dilemma two more times since my initial reading, I’ve come to believe that Pollan’s passion for stories explains a lot about the book. For one thing, it does much to explain the book’s popular success. Not only does Pollan like stories, but he’s good at telling them. In naming The Omnivore’s Dilemma one of the ten best books of 2006, the New York Times called Pollan “the perfect tour guide,” praising his writing as “incisive and alive.” Even B.R. Myers of The Atlantic, in a review that condemned the work as “a record of the gourmet’s ongoing failure to think in moral terms,” conceded that “Pollan writes of the role of corn in American life in such an improbably thrilling manner that I have to recommend the book.”

At the same time, his fixation with stories helps to explain why the book troubles me in some ways. In The Omnivore’s Dilemma, stories aren’t just a way to communicate facts while keeping the reader engaged. One might even say that the facts are secondary to the stories. Rather than base stories on the facts, Pollan chooses stories to fit an overarching reactionary thesis: The best way to eat is following nature and tradition, and our attempts at progress only make things worse. The facts, then, are worked into his narratives, but sometimes they don’t really fit.

Science is one victim of Pollan’s reactionary thesis. Nutritional science receives part of the blame for America’s health problems. “We place our faith in science to sort out for us what culture once did with rather more success” (303), he writes. Yet much of his evidence that “we place our faith in science” lies in our susceptibility to weight-loss diets and food fads that aren’t supported by scientific consensus. Moreover, he seems oblivious to the successes of nutritional science in curing nutrient deficiencies, some of which existed in traditional diets. (To be fair, I do recall Pollan devoting an entire sentence to this point in In Defense of Food.)

Science also receives unfair treatment in the agricultural context. Pollan attempts to summarize parts of Sir Albert Howard’s An Agricultural Testament, which he calls the organic movement’s bible. Yet he makes Howard’s work out to be some sort of anti-science treatise, when it just isn’t. Pollan concludes from Howard’s treatment of humus, “To reduce such a vast biological complexity to [nitrogen, phosphorous, and potassium] represented the scientific method at its reductionist worst” (147). While Howard offers plenty of criticism of modern agricultural science in particular, he does not criticize the scientific method more broadly. Indeed, he even calls aspects of conventional agriculture unscientific, proposes a few scientific experiments, and expresses his hope that science be among the tools of the agricultural investigators of the future. Howard’s work isn’t an argument against science. It’s an argument for better science.

Pollan’s chapters on the fast food chain are probably his strongest, but even there he occasionally oversteps. For example, he suggests that E. coli O157:H7 live only on feedlot cattle, when the scientific literature indicates that this deadly strain of bacteria is about as prevalent in grass-fed cattle. Later, he goes on to include one of the active ingredients in baking powder on a list of “quasiedible substances ” (113), apparently because of its chemical name. In both of these instances, he criticizes something new — feedlots in the first and baking powder in the second — with the effect of making something traditional seem more appealing.

The primary beneficiary of the reactionary narrative is the pastoral food chain, as represented by Joel Salatin’s Polyface Farm. Even as Salatin describes his farm is a “postindustrial enterprise” (191), he explains that in some sense his farming methods aren’t really new at all; they imitate the ecological relationships that exist in nature. To Pollan the farm is “a scene of almost classic pastoral beauty” (124). Its product, he says, “looks an awful lot like the proverbially unattainable free lunch” (127).

Pollan credits Salatin’s farming methods with revitalizing Polyface’s soil without chemical fertilizers. In particular, he writes,

The chief reason Polyface Farm is completely self-sufficient in nitrogen is that a chicken, defecating copiously, pays a visit to virtually every square foot of it at several points during the season. (210)

It’s hard to tell whether he grasps the fact that the nitrogen in the chickens’ feces comes from the food they eat, eighty percent of which is grain-based feed from off the farm. What is certain, though, is that he doesn’t raise the question of what is happening to the land where that feed is grown. We would expect from the earlier chapters that the corn and soy in the feed was grown on a farm that was less classic, less pastoral, and less beautiful than Polyface, so it’s striking that Pollan should choose not to look further. He also doesn’t bother to discuss the question of whether that feed grain might be more efficiently used to feed people directly. Either of these questions would be raised in a more fact-driven work, but there’s simply no room for them in The Omnivore’s Dilemma, as the answers might not fit the thesis.  (Of course, when Pollan later mentions “a denial of reality that can be its own form of hubris” (361), he’s talking about the vegetarians.)

As for the chickens, Pollan buys into Salatin’s argument that they are a purely artisanal product. He doesn’t mention that they are the same Cornish Cross hens that in the context of his Whole Foods meal represented “the pinnacle of industrial chicken breeding,” and which “grow so rapidly…that their poor legs cannot keep pace” (171).

Pollan also points out that Salatin’s pastures remove carbon dioxide from the atmosphere. There’s no mention, however, of the carbon dioxide emissions resulting from Salatin’s hugely inefficient distribution system, which involves large numbers of cars traveling long distances to the farm. (This omission comes even after he’s told us about the fossil fuels used to transport his industrial organic fruits and vegetables from distant farms.) When Pollan tells us that one customer drives 150 miles each way to the farm, it’s merely to be taken as proof of the quality of Polyface meats. There’s no mention of any environmental impact.

Where Pollan’s dedication to his reactionary thesis is perhaps most obvious is in his discussion of vegetarianism. For although there are prominent conservative vegetarians (Matthew Scully among them), vegetarianism today is rooted in a progressive idea. It requires us to accept that we can do something, namely eat, better than our ancestors did it. Indeed, Pollan writes,

Vegetarianism is more popular than it has ever been, and animal rights, the fringiest of fringe movements until just a few years ago, is rapidly finding its way into the cultural mainstream. I’m not completely sure why this should be happening now, given that humans have been eating animals for tens of thousands of years without too much ethical heartburn. (305)

Vegetarianism is something new, and his preferred hypothesis for its recent success is the weakening of our traditions:

But it could also be that the cultural norms and rituals that used to allow people to eat meat without agonizing about it have broken down for other reasons. Perhaps as the sway of tradition in our eating decisions weakens, habits we once took for granted are thrown up in the air, where they’re more easily buffeted by the force of a strong idea or the breeze of fashion. (306)

Being something new and representing a challenge to age-old traditions, vegetarianism simply doesn’t fit with Pollan’s reactionary message. In the reactionary view, it doesn’t make much more sense than high-fructose corn syrup or factory farms. As such, it doesn’t receive serious consideration.

Even before his section on the ethics of eating animals, there are signs that he won’t take his debate seriously. He tells us, for example, that his friends’ son is “fifteen and currently a vegetarian” (271), as though vegetarianism is merely a teenage phase. He also makes no secret of the fact that he’s already made the decision to go hunting even before tackling the ethical issues associated with eating animals.

Pollan gives up meat for a while, inspired by an argument of Peter Singer: “No one in the habit of eating an animal can be completely without bias in judging whether the conditions in which that animal is reared cause suffering” (312). Yet he identifies himself as “a reluctant and, I fervently hoped, temporary vegetarian” (313), so it’s not at all clear that the experiment does anything to lessen his bias.

As a vegetarian, Pollan struggles with the social ramifications of eating differently. He points out that “my new dietary restrictions throw a big wrench into the basic host-guest relationship” (313) and decides, “I’m inclined to agree with the French, who gaze upon any personal dietary prohibition as bad manners” (313). Yet he’ll find himself able to justify only a very limited kind of meat-eating, which likewise represents a “personal dietary prohibition.” He then proceeds to discuss his alienation from traditions like the Passover brisket, apparently not allowing for the possibility that traditions might evolve over time. This rigid view of tradition is an odd one considering his plans to hunt an unkosher pig.

Pollan then moves on to a discussion of animal rights philosophy. He claims to be debating Peter Singer, but he’ll quote Matthew Scully when it better suits his point, never acknowledging any significant difference between the writers. Other times, he’ll just quote Singer out of context.

Pollan eventually argues for meat-eating on the grounds that it serves the interests of domesticated species, which would cease to exist if people didn’t eat them. He doesn’t do much in the way of building up the argument, only hinting at how the interest of a species might be defined and not even beginning to explain why such an interest is more important than the individuals.

Instead of building that argument, Pollan relays a story intended to show that animal activists are out of touch with nature. As Pollan tells it, The Nature Conservancy and the National Park Service need to kill feral pigs to save Santa Cruz Island’s endangered fox, and the animal rights and welfare people oppose the plan out of a single-minded concern for animal welfare. However, the very same Humane Society op-ed that Pollan cites to prove this point actually includes a substantive discussion of the project’s ecological goals. Moreover, Pollan does not address any of the more scholarly objections to the project, such as Jo-Ann Shelton’s argument that the restoration of Santa Cruz Island is motivated by human interest.

Pollan then launches into a section called “The Vegan Utopia,” where he points out practical difficulties of a vegan world. First, he reminds us that harvesting grains kills animals. It’s a true statement that people who care about animals should keep in mind, but Pollan goes on to suggest that we would minimize animal deaths by basing our diets on large ruminants. That claim is an apparent reference to a study that was quickly debunked. He then argues that a vegan world would force places like New England to import all of their food from distant places. It’s a dubious claim in view of existing production of soy, wheat, and vegetables in New England. He even goes so far as to suggest that the vegan food chain would be more dependent on fossil fuels and chemical fertilizers than our current food system. Thanks to the inefficiency of feeding grain to animals, that claim is almost certainly false.

As Myers has pointed out, Pollan does not mention a single thing he ate in his time as a vegetarian. Over the course of the book, Pollan describes at least ten meat-based meals, four of those in exquisite detail, so it’s telling that he doesn’t consider vegetarian cuisine to be worth writing about.

Pollan goes hunting, shoots his sow, and even enjoys the experience. Yet when he finds himself disgusted by the sights and smells of cleaning the pig, Pollan can’t help but take one more jab at vegetarians. He expresses pity for the “tofu eater” for his “dreams of innocence” (361), seemingly rejecting the idea that we should even try to do better.

In spite of all these points of contention, I should acknowledge that Pollan gets plenty right in the book. There’s a lot that’s wrong with modern industrial food production. Making bad changes to our food supply has had profound negative consequences for the environment, public health, and animal welfare. On these topics, Pollan can remain faithful to his reactionary thesis while still representing the facts reasonably well. And so a reader learns about things like the psychology of supersizing, the environmental toll of growing corn to feed ruminants, and the miserable life of a battery-caged layer hen.

I suspect that many people find the information about industrial animal agriculture more powerful because they come from an author who so roundly rejects vegetarianism. After relaying the horrors of forced-molting and cannibalism in battery cages, Pollan writes,

I know, simply reciting these facts, most of which are drawn from poultry trade magazines, makes me sound like one of the animal people, doesn’t it? I don’t mean to (remember, I got into this vegetarian deal assuming I could go on eating eggs), but this is what can happen to you when…you look. (318)

It’s much harder for a reader to dismiss a message as the sentimental ramblings of one of the “animal people” when it’s coming from somebody who enjoys beating up on vegetarians.

In this way, The Omnivore’s Dilemma is a book that bring awareness about important issues to a wide audience. The fact of it being such an enjoyable read further expands that audience. However, it should be at most a starting point for those learning about where their food comes from because the underlying reactionary premise sometimes leads Pollan astray. We live in a world that is increasingly unnatural and unlike the one that shaped our cultural traditions. Our population is growing, our planet is warming, and our values and lifestyles have evolved. It doesn’t make sense for our food chain to remain in the past. As innovations like battery cages and high-fructose corn syrup show, not all ideas are good ones, but that shouldn’t stop us from trying to make progress. The future will present us with new challenges, and we’d do well to keep an open mind to new solutions.

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Another look at the nutrient cycle

Last week, I wrote about this claim on Michael Pollan’s new website:

A truly sustainable agriculture will involve animals, in order to complete the nutrient cycle, and those animals are going to be killed and eaten.

I want to revisit this claim because it relates to something I’ve recently read in The Omnivore’s Dilemma.

It seems to me that to say that farm animals “complete the nutrient cycle” is to miss a very important point. Every time we take food — whether it be from plant or animal source — from a farm, we’re taking nutrients away. Unlike wild animals, though, we don’t tend to return all of those nutrients when we’re done with them. Instead, we flush them down the toilet, sending them to septic tanks or sewage treatment plants. (Some nutrients eventually find their way back to the farm, but the process is far less direct than in nature.)

I want to focus on nitrogen in particular, since Pollan writes about it quite a bit. When we take food from a farm, we’re removing nitrogen from the system. In order to continue to produce food on that land, we need to somehow replenish that nitrogen. As it happens, nitrogen is plentiful in the atmosphere. However, atmospheric nitrogen isn’t usable to plants and animals. It needs to be converted to a biologically-available form, which — as Pollan writes on page 42 — is done naturally by nitrogen-fixing bacteria in the roots of leguminous plants or synthetically by the Haber-Bosch process. There are a few other ways that nitrogen can be fixed naturally, such as by lightning or bacteria living symbiotically with termites, but the key fact is that farm animals don’t contribute to nitrogen fixation.

What this means is that when animal manure is used to fertilize plants, the nitrogen it provides was fixed either by the Haber-Bosch process or by nitrogen-fixing bacteria in the roots of plants. Any nitrogen animals leave on the pasture was ingested in their food. This is a point that Pollan seems to miss when he writes,

The chief reason Polyface Farm is completely self-sufficient in nitrogen is that a chicken, defecating copiously, pays a visit to virtually every square foot of it at several points during the season. (210)

Polyface Farm isn’t completely self-sufficient in nitrogen, though. There’s plenty of nitrogen in the eighty percent of the chickens’ diet that Pollan has told us (just a few sentences earlier) comes from  corn and soy that Salatin buys. For the soil to maintain a stable nitrogen level from year to year, it’s necessary for the chicken feed together with the nitrogen-fixing bacteria in the roots of clover  and other legumes to provide enough nitrogen to replenish whatever is removed from the farm in food for humans. Passing through the chickens’ digestive systems doesn’t increase the amount of biologically-available nitrogen in the feed. (In his very next sentence, Pollan describes the chicken feed as Polyface’s “sole off-farm source of fertility,” apparently seeing no contradiction with the claim of self-sufficiency.)

What farm animals might be said to do with nutrients is to take them from grasses we can’t eat (though we can apparently eat clover like that on Salatin’s pasture) and convert them to a form that we can eat. Pollan does also describe at length how intensive grazing increases the productivity and diversity of the pasture. I can’t see how either of these roles would be said to be completing a nutrient cycle, though.

In the comments of my last post on the subject, Andy D and bill suggested using human manure, or humanure to fertilize crops. I don’t know enough about the public health implications, so I’m not going to endorse the idea. I will say, however, that using humanure would return the nutrients that have been removed from the farm. If Pollan wants to “complete the nutrient cycle” in any meaningful sense of the word “cycle,” it seems to me that humanure would do a lot more to this end than farm animals would.

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Sir Albert Howard and the scientific method

In describing the origins of organic agriculture, Pollan leans heavily on Sir Albert Howard’s An Agricultural Testament, which he calls “the movement’s bible” (145). Pollan explains that Howard’s work is the story of “a Fall” in which the “serpent” is Baron Justus von Liebig, who showed that plants need only nitrogen, phosphorous, and potassium to grow.  Howard called this the “NPK mentality” after the chemical symbols for those three elements.

After explaining that humus-rich soil does much more for plants than provide those three nutrients, Pollan writes,

To reduce such a vast biological complexity to NPK represented the scientific method at its reductionist worst. Complex qualities are reduced to simple quantities; biology gives way to chemistry. As Howard was not the first to point out, that method can only deal with one or two variables at a time. The problem is that once science has reduced a complex phenomenon to couple of variables, however important they may be, the natural tendency is to overlook everything else, to assume that what you can measure is all there is, or at least all that really matters. When we mistake what we can know for all there is to know, a healthy appreciation of one’s ignorance in the face of a mystery like soil fertility gives way to the hubris that we can treat nature as a machine. (147)

Though Pollan doesn’t say so directly, one might guess from reading his account that Howard’s work was some sort of anti-science treatise. The complete text of An Agricultural Testament is available online, and Howard does indeed devote a full chapter (Chapter 13) to criticizing agricultural science. This chapter criticizes many aspects of agricultural science as it was practiced in his day, such as the tendency to fit agricultural problems into existing branches of science, the insistence on quantitative results, the role of economics in research, and the failure of scientists to adequately communicate their results to farmers. Notably absent, however, is any criticism of the scientific method.

To clarify this distinction, I think it’s worth discussing what is meant by the scientific method. This refers to a very general method for gathering and organizing knowledge. Loosely speaking, it’s a sort of systematization of the trial-and-error process. It involves seeking the answer to a question by using observations to make a hypothesis, using the hypothesis to make a prediction, testing the hypothesis experimentally, and using the results to form a new hypothesis.

If the NPK mentality led agriculture astray, I would argue that it’s not because the scientific method is inherently reductionist but because science was applied badly. The NPK mentality confuses the question of what plants need, at minimum, to grow (answer: nitrogen, phosphorous, potassium) with the question of how we should grow crops. It’s absolutely a reductive mindset, but that’s the fault of the scientists, not the scientific method.

To see that better science is possible, one need look no further than Howard’s An Agricultural Testament. The twelfth chapter is titled “Soil Fertility and National Health” and sets out to address a general question: “How does the produce of an impoverished soil affect the men and women who have to consume it?” It’s a much broader question than the one that guides the NPK mentality.

I would be remiss if I didn’t mention that the age of Howard’s work shows through in this chapter. After suggesting the idea of experimenting on subjects in concentration camps, convict prisons, and asylums, Howard simply writes, “Objections…would almost certainly be raised,” and he later tells us that the people of northern India include “some of the finest races of mankind.” Nonetheless, the chapter does present ideas about how the scientific method might be applied to agriculture to produce better results.

Although Howard does acknowledge the impracticality of experimenting on humans, he also relays some observations on relationships between various groups of people in India and the health of their soils. This isn’t a controlled experiment like the ones that Liebig and his followers used to justify the NPK mentality, but it is an example of what is called a “natural experiment,” an experiment in which the controls are assigned by nature (rather than by researchers). Howard also presents limited scientific evidence from studies in Britain and writes that more work is needed. Notable also is his proposal,

The agricultural colleges with their farms should devote some of their resources to feeding themselves, and so demonstrating what the products of well-farmed land can accomplish.

In doing so, he proposes to have the agricultural researchers address a question more useful than the one that led them to NPK. He proposes that they should address the question of which agricultural methods are best for human health and also that they should test their hypotheses on themselves.

Pollan’s retelling of Howard’s work seems to be guided by an overly simplistic notion of the nature of scientific inquiry. Reading Pollan’s work, one might think that science refers only to work done in laboratories. He writes,

Howard’s concept of organic agriculture is premodern, arguably even antiscientific: He’s telling us we don’t need to understand how humus works or what compost does in order to make good use of it.

But there’s nothing antiscientific about this idea. Indeed, Howard presents scientific evidence that humus does work, including the fact that it works in nature. To say that we shouldn’t try to find out why humus works would be antiscientific, but to say that we can reap its benefits without understanding how it works is not.

Contrast this with a claim that Howard makes in his eleventh chapter:

The policy of protecting crops from pests by means of sprays, powders, and so forth is unscientific and unsound as, even when successful, such procedure merely preserves the unfit and obscures the real problem — how to grow healthy crops.

To Howard, it is conventional — rather than organic — agriculture that is unscientific. To him, the problem with conventional agriculture isn’t that it’s scientific but that it isn’t. Whereas Pollan believes that conventional agriculture is driven by “the scientific method at its reductionist worst,” Howard considers reductionism to be unscientific, a consequence of researchers focusing on the wrong problem.

Howard reaffirms his belief in science in his concluding chapter, where he writes,

[T]he investigator of the future will only differ from the farmer in the possession of an extra implement — science — and in the wider experience which travel confers.The future standing of the research worker will depend on success: on ability to show how good farming can be made still better.

There should be no doubt that Sir Albert Howard believed the scientific method to be an important tool for agricultural research. Sadly, Pollan relays Howard’s work in a way that not only fails to make this clear but also promotes overly simplistic ideas about what science is.

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