Michael Pollan on the Links Between Biodiversity and Health
By Jack Hitt
It was an odd paradox that led author Michael Pollan to write a book about cooking. How was it, he wondered, that in an era when Americans were buying more and more pre-packaged, ready-to-eat food, they were spending more time watching programs about cooking on television?
That question led to his new book, Cooked, which like his previous books, delves into issues relating to the connections between the environment and what we eat, and, more broadly, to humanity’s relationship to the natural world. Pollan argues that taking control of cooking may be the single most important step an individual can take to help make the American food system healthier and more sustainable.
In an interview with Yale Environment 360 contributor Jack Hitt, Pollan talked about how his research led him on a journey that ranged from the monoculture fields of U.S. commodity agriculture to the bacterial world inside the human body. And he noted the fundamental importance of biodiversity—in the landscape and the farm field, as well as in people’s diets.
“This may prove to be the key legacy of ecology—what it teaches us about health,” Pollan said. “Who would have thought?”
Hitt: In your new book, Cooked, you head to the stove, where previously you had been in the garden or the feed lot or a cornfield. Has taking your observations indoors changed the way you think about the big outdoors?
Pollan: I would say it has. Like most journalists, I tended to gravitate toward exotic places, places my reader hadn’t been—like the feedlot or the laboratory. That’s one of the things we do—we’re kind of these designated inquirers. And it was my experience on the feedlot and other sites of industrialized agriculture that sent me into the kitchen. Because I came to realize that the way we cook, or whether we cook or not, or who’s doing the cooking, is creating that other landscape. And it really was the industrializing of cooking—which we call food processing, done by corporations, of course—which drove the industrialization of our farming.
It’s McDonald’s that gives us the giant monocultures of Russet Burbank potatoes that I wrote about in Botany of Desire, or the feed lots that I wrote about in Omnivore’s Dilemma. And I came to realize that you couldn’t understand those landscapes without reference to these everyday decisions we make about whether we’re going to cook or whether we’re going to go out to McDonald’s. That they were linked. I never expected to write a book about a landscape as familiar as my kitchen, or anyone’s kitchen. But that’s of course the great lesson of ecology—these things are connected.
Hitt: Recently you’ve described yourself as a “superorganism.” What do you mean?
Pollan: One of the byways of this book was learning about fermentation, and meeting these “fermentos” as I call them—these passionate fermentation geeks who have a completely different relationship to bacteria than most of us do. And they taught me a different way to think about bacteria. Learning about these external fermentations, whether you’re talking about tea or beer or bread, very quickly gets you into its mirror image, which is the fermentation within, the fermentation in your own large intestine and what those bacteria are up to.
So I followed this path into the microbiology of the gut and was amazed to learn that first, we are only 10 percent human, if you’re counting cells, and 90 percent bacterial. And those bacteria have a profound impact on your health, on your mood, on your immune system, on your metabolism and whether you’re going to become infected by bad bacteria or not. And it turns out that health—which we think of as a property of us, the human cells in our body—turns out to be a collective property of the whole community. That community consists of these microbes. You can’t be healthy if they’re not … That’s a radical rethinking of who we are.
Hitt: At one point you referred to “the impoverished westernized microbiome,” and you posed the question of whether the human body needs what some microbiologists call “restoration ecology.” So you’re applying environmental metaphors to the human body. How might this kind of language make us think in a new way about our bodies?
Pollan: I think when you bring the concepts of ecology into your body, that’s a revolutionary new paradigm for medicine and for the philosophy of human identity. It breaks down the “us and them” attitude we bring to nature. It’s a very direct implication of the natural world in the body. We know when we eat, we’re always taking nature into us. But the idea that we’re a host to an ecological community and that that ecological community is obviously shaped by what’s going on in the world—whether we’re talking about toxins, antibiotics—you’re really breaking down that barrier between us and nature out there. Nature is passing through us. I didn’t tease out these implications, but I think it does have important implications for how you think about nature. It definitely brings it home.
Hitt: And also how you think about what you eat?
Pollan: Yes. If it doesn’t necessarily change your diet, it does change your attitude toward the various chemical compounds that poison this environment. We’ve understood that feeding antibiotics to livestock is a public health risk because of the rise of superbugs and antibiotic-resistant microbes, and that’s the reason people have campaigned to remove them. But it turns out there’s another reason to remove them and that is that these antibiotics are poisoning and cutting down on the biodiversity inside you. So there are implications of knowing this that go beyond diet.
Hitt: How was it that scientists recently came to start talking about the human microbiome?
Pollan: There are two tools that have allowed for this wilderness to be explored. One is this new sequencing technology. But the other was theories of ecology. It was when scientists began thinking, “Hey, what if we ask the questions that ecosystems scientists ask?” Which was radical for medicine. Medicine doesn’t usually think that way. And that really opened it up. And they started using terms like community dynamics and invasion resistance. And exotic species. And resilience. So there was an intellectual tool and there was a technical tool. And they were both required to make the breakthroughs we’re starting to make.
Hitt: Wow, that’s cool. So, there really was a kind of theoretical borrowing?
Pollan: Yes. And this may be prove to be a key legacy of ecology—what it teaches us about health. Who would have thought?
Hitt: What might the last 50 years of environmental action policy and environmental education teach us as we begin to discover the Amazonian rainforest that resides in our gut?
Pollan: We know that we’re connected and that there are links between soil and health, and water and health. This is just another way to draw those links.
I was really struck by how many of the microbiologists were concerned about very common food additives. Xanthan gum and polysorbate 80, these emulsifiers, which seem like one of the least toxic of food additives—these are just chemicals that allow water and oil to be held in solution so they don’t come apart. And if you’re making processed food, that’s really important because it looks really nasty when the sauce in your frozen, I don’t know, beef Stroganoff, starts separating.
These [emulsifiers] are very important in processed food. But it turns out that they may be damaging the lining of the gut. And that’s not what the FDA [U.S. Food and Drug Administration] ever tested for ... So we really have to rethink toxicology in light of the microbiome.
Hitt: These microbes evolve really, really fast. As you point out, some of them take 20 minutes a generation. That’s crazy—it’s so at odds with everything we know about life out here on the megafauna scale of existence, where evolution is slow, really slow. Is there any evidence that this microbial speed will advantage us in some way as we all adapt to, say, global warming?
Pollan: One of the questions I’ve struggled with in writing about the gut and writing about fermentation in the book is how weird it is to outsource very important functions of life to microbes and not have evolved our own systems for dealing with metabolism, temperament, immunity. I mean, it is a huge outsourcing of a critical life function.
One case I thought was absolutely fascinating is this difference in the gut of Japanese people and Americans. There’s a very common bacteria that we all share, that all humans have in their gut and it’s involved in digesting polysaccharides of complex carbohydrates and plants. And the Japanese version of it has a gene that allows it to break down seaweed that we can’t break down. When you eat seaweed in a Japanese restaurant, you’re not getting the nutritional value from it that a Japanese person is getting. And they actually traced the source of that gene and it came from the bacteria that hang out on seaweed in the ocean. In other words, the bacteria who first learned how to digest seaweed. Through the eating of enough seaweed, this bacteria that is common in the gut of the Japanese borrowed this bit of genetic information and uses it now to digest seaweed. And so now it’s a permanent part of the genome of that bug.
There’s an example of how the microbiome evolved to take advantage of a change in the environment—i.e., Japanese eating of seaweed—probably because they needed to. And the same thing is true with, say, dealing with a new toxin, detoxifying and other changes in our environment. It’s kind of evolution on fast forward. That’s probably critical to our ability to adapt to change and it may become more critical as we face more rapid and radical environmental changes.
Hitt: You’ve written in the past about arguments over preserving “pristine” nature or humans intervening to “garden” nature. How does that apply the human microbiome?
Pollan: Well, if you want to adjust to changes in the environment, you need the genetic resources. This ability to adapt probably depends on high levels of biodiversity, and that’s precisely what we have damaged with the Western diet and the Western overuse of antibiotics and other antimacrobials. As scientists have pointed out to me, if you damage the biodiversity enough, the various genes you need to cope will not be there. And the microbiome will come up empty-handed in meeting the challenges it faces.
So, that’s an argument for restoring the biodiversity of the gut—gardening it, if you will—introducing more species. That may turn out to be the value of these pristine microbiomes, that the genetic resources we need may exist there. We may have to culture those and reintroduce those. We don’t know enough to say exactly how to garden the microbiome, but we may need to. We may need to just give it enough biodiversity to be resilient to change. And you see, I’m using all the words we use when we’re talking about a farm or any land.
Hitt: So, now that you’re very intimate with the alchemy of cooking and fire, water, air and earth, how would you change America’s farm policy if you could, right now?
Pollan: Well, I would try to create incentives that drive diversification. I still feel that the great evil of American agriculture is monoculture. It really does contribute to so many problems at the level of the field and the pests, but also at the level of the diet. The thing you learn is the importance of diversity in what you eat, and to the extent you would drive diversity [in farm policy], you would also be creating raw materials for cooking rather than raw materials for processed food, which are mostly corn and soy.
I love this term “specialty crop.” That’s what the USDA [U.S. Department of Agriculture] lingo is for anything you grow that you could actually eat—fruits and vegetables. Corn and soy and rice and wheat, these are commodity crops—in the case of rice you do eat it directly, but everything else has to be heavily processed first. Right now, we actually have laws that prohibit farmers receiving subsidies to grow commodity crops from growing specialty crops. They get fined. If you’re growing corn and soy, and you want to put in 20 acres of tomatoes because somebody’s doing some local canning deal in your county and you want to get in on it and diversify, you get fined. I know farmers who have been fined $40,000 or $50,000 for doing that. That’s unconscionable. We should be encouraging farmers to diversify, for both economic and ecological reasons.
In 2010, world leaders agreed to 20 targets to protect Earth's biodiversity over the next decade. By 2020, none of them had been met. Now, the question is whether the world can do any better once new targets are set during the meeting of the UN Convention on Biodiversity in Kunming, China later this year.
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By Ana Maldonado-Contreras
- Your gut is home to trillions of bacteria that are vital for keeping you healthy.
- Some of these microbes help to regulate the immune system.
- New research, which has not yet been peer-reviewed, shows the presence of certain bacteria in the gut may reveal which people are more vulnerable to a more severe case of COVID-19.
You may not know it, but you have an army of microbes living inside of you that are essential for fighting off threats, including the virus that causes COVID-19.
How Do Resident Bacteria Keep You Healthy?<p>Our immune defense is part of a complex biological response against harmful pathogens, such as viruses or bacteria. However, because our bodies are inhabited by trillions of mostly beneficial bacteria, virus and fungi, activation of our immune response is tightly regulated to distinguish between harmful and helpful microbes.</p><p>Our bacteria are spectacular companions diligently helping prime our immune system defenses to combat infections. A seminal study found that mice treated with antibiotics that eliminate bacteria in the gut exhibited an impaired immune response. These animals had low counts of virus-fighting white blood cells, weak antibody responses and poor production of a protein that is vital for <a href="https://doi.org/10.1073/pnas.1019378108" target="_blank">combating viral infection and modulating the immune response</a>.</p><p><a href="https://doi.org/10.1371/journal.pone.0184976" target="_blank" rel="noopener noreferrer">In another study</a>, mice were fed <em>Lactobacillus</em> bacteria, commonly used as probiotic in fermented food. These microbes reduced the severity of influenza infection. The <em>Lactobacillus</em>-treated mice did not lose weight and had only mild lung damage compared with untreated mice. Similarly, others have found that treatment of mice with <em>Lactobacillus</em> protects against different <a href="https://doi.org/10.1038/srep04638" target="_blank" rel="noopener noreferrer">subtypes of</a> <a href="https://doi.org/10.1038/s41598-017-17487-8" target="_blank" rel="noopener noreferrer">influenza</a> <a href="https://doi.org/10.1371/journal.ppat.1008072" target="_blank" rel="noopener noreferrer">virus</a> and human respiratory syncytial virus – the <a href="https://doi.org/10.1038/s41598-019-39602-7" target="_blank" rel="noopener noreferrer">major cause of viral bronchiolitis and pneumonia in children</a>.</p>
Chronic Disease and Microbes<p>Patients with chronic illnesses including Type 2 diabetes, obesity and cardiovascular disease exhibit a hyperactive immune system that fails to recognize a harmless stimulus and is linked to an altered gut microbiome.</p><p>In these chronic diseases, the gut microbiome lacks bacteria that activate <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">immune cells</a> that block the response against harmless bacteria in our guts. Such alteration of the gut microbiome is also observed in <a href="https://doi.org/10.1073/pnas.1002601107" target="_blank" rel="noopener noreferrer">babies delivered by cesarean section</a>, individuals consuming a poor <a href="https://doi.org/10.1038/nature12820" target="_blank" rel="noopener noreferrer">diet</a> and the <a href="https://doi.org/10.1038/nature11053" target="_blank" rel="noopener noreferrer">elderly</a>.</p><p>In the U.S., 117 million individuals – about half the adult population – <a href="https://health.gov/our-work/food-nutrition/2015-2020-dietary-guidelines/guidelines/" target="_blank" rel="noopener noreferrer">suffer from Type 2 diabetes, obesity, cardiovascular disease or a combination of them</a>. That suggests that half of American adults carry a faulty microbiome army.</p><p>Research in my laboratory focuses on identifying gut bacteria that are critical for creating a balanced immune system, which fights life-threatening bacterial and viral infections, while tolerating the beneficial bacteria in and on us.</p><p>Given that diet affects the diversity of bacteria in the gut, <a href="https://www.umassmed.edu/nutrition/melody-trial-info/" target="_blank" rel="noopener noreferrer">my lab studies show how diet can be used</a> as a therapy for chronic diseases. Using different foods, people can shift their gut microbiome to one that boosts a healthy immune response.</p><p>A fraction of patients infected with SARS-CoV-2, the virus that causes COVID-19 disease, develop severe complications that require hospitalization in intensive care units. What do many of those patients have in common? <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6912e2.htm" target="_blank" rel="noopener noreferrer">Old age</a> and chronic diet-related diseases like obesity, Type 2 diabetes and cardiovascular disease.</p><p><a href="http://doi.org/10.1016/j.jada.2008.12.019" target="_blank" rel="noopener noreferrer">Black and Latinx people are disproportionately affected by obesity, Type 2 diabetes and cardiovascular disease</a>, all of which are linked to poor nutrition. Thus, it is not a coincidence that <a href="https://www.cdc.gov/mmwr/volumes/69/wr/mm6933e1.htm" target="_blank" rel="noopener noreferrer">these groups have suffered more deaths from COVID-19</a> compared with whites. This is the case not only in the U.S. but also <a href="https://www.washingtonpost.com/world/europe/blacks-in-britain-are-four-times-as-likely-to-die-of-coronavirus-as-whites-data-show/2020/05/07/2dc76710-9067-11ea-9322-a29e75effc93_story.html" target="_blank" rel="noopener noreferrer">in Britain</a>.</p>
Discovering Microbes That Predict COVID-19 Severity<p>The COVID-19 pandemic has inspired me to shift my research and explore the role of the gut microbiome in the overly aggressive immune response against SARS-CoV-2 infection.</p><p>My colleagues and I have hypothesized that critically ill SARS-CoV-2 patients with conditions like obesity, Type 2 diabetes and cardiovascular disease exhibit an altered gut microbiome that aggravates <a href="https://theconversation.com/exercise-may-help-reduce-risk-of-deadly-covid-19-complication-ards-136922" target="_blank" rel="noopener noreferrer">acute respiratory distress syndrome</a>.</p><p>Acute respiratory distress syndrome, a life-threatening lung injury, in SARS-CoV-2 patients is thought to develop from a <a href="http://doi.org/10.1016/j.cytogfr.2020.05.003" target="_blank" rel="noopener noreferrer">fatal overreaction of the immune response</a> called a <a href="https://theconversation.com/blocking-the-deadly-cytokine-storm-is-a-vital-weapon-for-treating-covid-19-137690" target="_blank" rel="noopener noreferrer">cytokine storm</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">that causes an uncontrolled flood</a> <a href="http://doi.org/10.1016/S2213-2600(20)30216-2" target="_blank" rel="noopener noreferrer">of immune cells into the lungs</a>. In these patients, their own uncontrolled inflammatory immune response, rather than the virus itself, causes the <a href="http://doi.org/10.1007/s00134-020-05991-x" target="_blank" rel="noopener noreferrer">severe lung injury and multiorgan failures</a> that lead to death.</p><p>Several studies <a href="https://doi.org/10.1016/j.trsl.2020.08.004" target="_blank" rel="noopener noreferrer">described in one recent review</a> have identified an altered gut microbiome in patients with COVID-19. However, identification of specific bacteria within the microbiome that could predict COVID-19 severity is lacking.</p><p>To address this question, my colleagues and I recruited COVID-19 hospitalized patients with severe and moderate symptoms. We collected stool and saliva samples to determine whether bacteria within the gut and oral microbiome could predict COVID-19 severity. The identification of microbiome markers that can predict the clinical outcomes of COVID-19 disease is key to help prioritize patients needing urgent treatment.</p><p><a href="https://doi.org/10.1101/2021.01.05.20249061" target="_blank" rel="noopener noreferrer">We demonstrated</a>, in a paper which has not yet been peer reviewed, that the composition of the gut microbiome is the strongest predictor of COVID-19 severity compared to patient's clinical characteristics commonly used to do so. Specifically, we identified that the presence of a bacterium in the stool – called <em>Enterococcus faecalis</em>– was a robust predictor of COVID-19 severity. Not surprisingly, <em>Enterococcus faecalis</em> has been associated with <a href="https://doi.org/10.1053/j.gastro.2011.05.035" target="_blank" rel="noopener noreferrer">chronic</a> <a href="https://doi.org/10.1016/S0002-9440(10)61172-8" target="_blank" rel="noopener noreferrer">inflammation</a>.</p><p><em>Enterococcus faecalis</em> collected from feces can be grown outside of the body in clinical laboratories. Thus, an <em>E. faecalis</em> test might be a cost-effective, rapid and relatively easy way to identify patients who are likely to require more supportive care and therapeutic interventions to improve their chances of survival.</p><p>But it is not yet clear from our research what is the contribution of the altered microbiome in the immune response to SARS-CoV-2 infection. A recent study has shown that <a href="https://doi.org/10.1101/2020.12.11.416180" target="_blank" rel="noopener noreferrer">SARS-CoV-2 infection triggers an imbalance in immune cells</a> called <a href="https://doi.org/10.1111/imr.12170" target="_blank" rel="noopener noreferrer">T regulatory cells that are critical to immune balance</a>.</p><p>Bacteria from the gut microbiome are responsible for the <a href="https://doi.org/10.7554/eLife.30916.001" target="_blank" rel="noopener noreferrer">proper activation</a> <a href="https://doi.org/10.1126/science.1198469" target="_blank" rel="noopener noreferrer">of those T-regulatory</a> <a href="https://doi.org/10.1038/nri.2016.36" target="_blank" rel="noopener noreferrer">cells</a>. Thus, researchers like me need to take repeated patient stool, saliva and blood samples over a longer time frame to learn how the altered microbiome observed in COVID-19 patients can modulate COVID-19 disease severity, perhaps by altering the development of the T-regulatory cells.</p><p>As a Latina scientist investigating interactions between diet, microbiome and immunity, I must stress the importance of better policies to improve access to healthy foods, which lead to a healthier microbiome. It is also important to design culturally sensitive dietary interventions for Black and Latinx communities. While a good-quality diet might not prevent SARS-CoV-2 infection, it can treat the underlying conditions related to its severity.</p><p><em><a href="https://theconversation.com/profiles/ana-maldonado-contreras-1152969" target="_blank">Ana Maldonado-Contreras</a> is an assistant professor of Microbiology and Physiological Systems at the University of Massachusetts Medical School.</em></p><p><em>Disclosure statement: Ana Maldonado-Contreras receives funding from The Helmsley Charitable Trust and her work has been supported by the American Gastroenterological Association. She received The Charles A. King Trust Postdoctoral Research Fellowship. She is also member of the Diversity Committee of the American Gastroenterological Association.</em></p><p><em style="">Reposted with permission from <a href="https://theconversation.com/a-healthy-microbiome-builds-a-strong-immune-system-that-could-help-defeat-covid-19-145668" target="_blank" rel="noopener noreferrer" style="">The Conversation</a>. </em></p>
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