Is Stress Edible?
Food production methods may be contributing to ecosystem-level stress.
I started with a simple question: Does consuming food containing stress hormones affect our bodies? After all, we are what we eat, and I was curious if the stress imparted on our foods—starting from when they are farm animals and plants all the way to when they end up on our fork—might have implications on our health. The question hurtled me down a rabbit hole into the mysterious wonderland of food science, a field famous for nonsensical riddles that would have shorted even Lewis Carroll’s fuse, riddles such as “Eat margarine instead of butter, but wait, don’t eat trans fats!” Decoding truths about how we should eat has profound implications for all stakeholders in the food system including consumers, policymakers and businesses.
The more time we spend in the wonderland of food science, the less we seem to understand what’s going on.
Like Alice in Alice in Wonderland, consumers today are inundated with messages from foods that beckon, “Eat me.” And like Alice, after doing what we’re told, we’re ballooning in size. The more time we spend in the wonderland of food science, the less we seem to understand what’s going on. Despite strong beliefs in popular culture, the scientific evidence behind common dietary recommendations remains conflicting and suboptimal. As in Through the Looking Glass, when it comes to sequels in dietary recommendations, we’re being told that perhaps the opposite of the prior truth is true: “Avoid fat, but eat lots of it!”
Even as a growing cacophony of commercially motivated science contributes to this confusion, many fundamental questions about food and public health remain unanswered. To start building a stronger foundation of evidence-based nutrition science, former FDA commissioner David Kessler, former USDA secretary Dan Glickman and I wrote a New York Times opinion piece in February that made a case for establishing a new federal agency dedicated to funding nutrition research—a National Institute of Nutrition. While the cost of using tax dollars to fund nutrition science may be high, the cost of not funding independent nutrition research may prove far higher, as the explosion of diet-related chronic diseases such as obesity and diabetes attests. Congress has taken notice.
While that effort simmers in the background, let’s get back to the original burning question about whether eating stressed foods might induce stress in human consumers. The short answer is that we still don’t know. But here is what we do know: Wounds caused during processing plant-based food produces ethylene, a plant stress hormone known to trigger stress responses in microbiomes, including in species such as proteobacteria that are present in human gut biomes. Furthermore, it is known that a stressed gut biome is associated with not only gastrointestinal issues but also stress and inflammatory responses in human hosts. Chain-linking the evidence, one wonders if ethylene in our plant-based foods induces stress, allergic or inflammatory cascades in humans and their gut biomes.
One can view the plant-associated microbiome, human gut microbiome and humans as a species as members of a larger holobiont—an ecosystem acting as a superorganism—that monitors, communicates and regulates information through chemical messengers across the ecosystem network. When such chemical messengers spread genuine alarm calls about ecological stress through the holobiont like a game of telephone, it helps the species survive. On the other hand, externalities that introduce illegitimate stress signals into this ecosystem-level communication network—including the large degree of stress imparted on plants during industrial production of food—could engender maladaptive stress responses in people.
Another external contributor of stress hormones into the ecosystem is the industrial production of ethylene for commercial use. Ethylene is the most synthesized chemical on the planet, surpassing 150 million metric tons of production per year. And ethylene is created by hydrocarbon combustion (including automobile exhaust), plastic degradation and forest fires. In other words, while industrial farming could be producing stress in plants, human industry and its byproducts are likely triggering ecosystem-level stress and inflammation. Also, since ethylene is inherently pyrogenic, one wonders if the rising concentrations of ethylene in the atmosphere are contributing to forest fires and climate change.
As for animal-based foods, it is still unknown whether consuming cortisol in food derived from stressed animals triggers stress responses in humans and their gut biomes. We do, however, know that cortisol induces stress responses in our gut biomes and consumption of prednisone, a synthetic analog of cortisol, promotes diabetes, hypertension and obesity in humans.
Among the most famous unsolved riddles in Alice in Wonderland is the Mad Hatter’s riddle: “Why is a raven like a writing desk?” The riddle is part of Carroll’s much-speculated embedded messages about food and the food chain—about eating and being eaten. My proposed solution to the Mad Hatter’s riddle is the following: The raven is like a writing desk in that food is information. It may be that the embedded message flowing through the food chain today is that humans are stressing out the ecosystem—and that the stress is coming back to bite us.
Perhaps it’s time for us to listen.