Does eating food that contains too many stress hormones—cortisol in meats, ethylene in plant-based foods, and other related hormones—trigger stress and inflammation in our bodies?
To date, scientists have overlooked the possibility that consuming stress hormones through food may be affecting our health. However, we make the case that food-borne stress hormones may be a missing link in the connection between food and health.
If substantiated, this hypothesis could lead to a fundamental shift in how we eat. Even putting aside personal health concerns, reducing stress hormones in our diet can help us imagine a better world, in a larger sense. We would care more not only about how food affects us, but also about how our consumption habits of animals and plants affects them. There are implications for the economy, too: Localism and sustainable agriculture could flourish as farm-to-fork quality control and alignment of interests become priorities.
Stress hormones are biochemicals produced by the body in response to any form of stress. In animals, the predominant stress hormone is cortisol. In plants, the predominant stress hormone is ethylene. These stress hormones produce a wide variety of well-characterized effects within the body of animals and plants that help them survive. What is far less known are the effects of these stress hormones when they are consumed by a different species.
A recent study of piglets published in the Journal of Animal Science by Purdue University scientist Elizabeth Petrosus found that when pigs are fed stress hormones such as cortisol or norepinephrine, their blood levels of these hormones spike, body temperatures rise and gut biomes shift. This poses some questions. How much cortisol or norepinephrine is lurking in our meat? Are these levels rising due to the stress put on animals by the food system? When we eat foods high in cortisol or norepinephrine, do our cortisol and norepinephrine levels spike? Since we know that long-term use of prednisone, a medicinal form of cortisol, is associated with higher rates of high blood sugar, high blood pressure, and obesity, could stress hormones in our foods be a mechanistic link between modern diets and the growing epidemic of diabetes, hypertension, and obesity?
The same pig study found that, due to negative feedback loops, the pigs eventually exhibited abnormally low blood levels of cortisol and norepinephrine due to overcorrection by the body. This poses some additional questions. Does a diet rich in stress hormones induce habituation—a loss of intrinsic capacity to respond to stress (detectable as adrenal insufficiency on ACTH stimulation test or autonomic insufficiency on baroreceptor sensitivity tests)? Since norepinephrine analogues (sympathomimetics) are the active ingredients in all rescue drugs for allergic rhinitis, asthma, and anaphylactic shock, we have made the case that intrinsic adrenal-autonomic insufficiency is a common underlying pathology in these conditions. We believe that baseline blood levels of norepinephrine and related stress hormones, as well as their ability to respond to stress on challenge tests, ought to be better studied in these patients.
We also wonder about the stress hormones (ethylene, etc.) levels in plant-based foods. It has been shown that ethylene—a marker of inflammation in our bodies—triggers stress response in some of the same bacteria that are commonly found in our gut. Stressed gut bacteria can activate stress in human hosts. Although generally regarded as safe, direct effects of consumed ethylene on the human body are poorly understood. It is noteworthy that, among other effects, the processing of food increases the levels of ethylene in our food significantly.
A consequence of chronic stress in animals is that they get fatter. A consequence of stress on fruits is they get sweeter. When combined, fatty and sweet ingredients serve as the foundation of all processed desserts. Humans—when they are stressed—crave foods abundant in fatty and sweet signatures of stressed foods: teens binging on ice cream during exam week or police officers taking breaks at donut shops. It is more than ironic that the word “desserts” spelled backwards is “stressed.”
While we await the answers to these health-related questions, we can start thinking about how we can reduce stress hormones in our meats and plant-based foods.
Here are examples of production and preparation practices that could reduce the amount of stress hormones in animal-based foods: (1) allowing them to live without too much chronic stress; (2) allowing them to live in free range, cage-free, wild, and natural environments; (3) reducing infectious, chemical, and environmental stress; (4) feeding them a diet containing low stress hormones—for example, wild grass versus processed corn (processing increases ethylene levels).
Here are examples of production and preparation practices that could reduce the amount of stress hormones in plant-based foods: (1) growing them in proper soil, season, and environments; (2) managing chemical, pest, infection, and water stress; (3) managing their harvest, transport, production, storage, preparation, and consumption in a way that minimizes ethylene production—keeping in mind that ethylene production continues to happen after harvest. On a side note, vegetative or immature tissues (e.g broccoli, celery, lettuce, and cabbage) release far less ethylene upon wounding, which could help explain their putative benefits in healthy diets.
Indeed, these practices generally align with most trends in healthy food movements. While it is intuitively appealing to speculate that the reduction of stress hormones might be the Occam’s razor that connects all of these disparate movements, empirical validation is still needed. One day, the “health quotient” of a food could be determined by its provenance far more than we now understand.
Imagine being able to eat your way to a better world. In that spirit, at a time when confusion reigns about almost everything going on in the planet, and people are asking us to remember a long list of rules on how to eat, here’s a simple rule that is easy to remember. If you stress it, it will stress you; if you treat it well, it will treat you well.
That’s the Golden Rule of food.
Joon Yun and Amanda Yun are Principals of the Yun Family Foundation.