As a practicing physician and expert in lectin-free nutrition, I grapple daily with the question: Why does our food sometimes make us sick - and how was this actually intended by nature?
In my daily practice, I see the biochemical consequences of what Navid Bayani describes so vividly. Nature is not a peaceful buffet, but a highly complex battlefield of evolution. Plants cannot run away; therefore, they have developed chemical defense strategies - including lectins. These proteins are the “fences” with which plants protect their vital organs (leaves, stems) and their offspring (seeds).
Particularly fascinating is the dichotomy between defense and invitation that we observe in the ripening of fruits: An unripe, green apple is full of lectins and camouflages itself among the foliage - it “doesn’t want” to be found yet. Only when the seed is ready does the plant change its strategy: The toxic lectins are broken down, sugar is stored, and the color shifts to a vivid red or yellow. Does this sound new to you? Well, even your grandfather would have known that green apples cause diarrhea and that they shouldn’t be picked prematurely in May, but rather you must wait until September - then they are ripe, lectin-free, and digestible.
Dr. Christian Gersch’s observations confirm a fundamental shift: While our grandparents still knew that legumes must be soaked overnight, he sees patients daily with digestive problems that can be traced directly to this lost knowledge. His clinical experience with lectin-free diets in autoimmune diseases shows: The body “remembers” the original dietary rules - it responds positively when we respect the plant defense mechanisms that Dr. Gersch describes so precisely.
In these modern times, filled with hustle and bustle and high expectations, hardly anyone finds the time to consciously consider what’s on their plate. Our brains are already overwhelmed with thoughts about everyday matters that still need to be processed subconsciously - leaving no time for proper preparation or for considering the potential health effects of the food. Yet sometimes it doesn’t even matter what happens inside our bodies, as long as we don’t notice it.
So we’ve tuned out our instincts, and we’re missing out on an important instinct that could actually keep us healthy. After all, the key to optimal nutrition lies deep within our instincts. Studies show that wild animals balance their macronutrients precisely without even realizing it.
Nature originally endowed us with perfect senses; in fact, we would “know” exactly what we need to eat. Animals do not eat their food blindly, but choose it instinctively. They know exactly when they need “what,” and primates demonstrate this as well, for example, by eating certain leaves and bark when they suffer from gastrointestinal discomfort, or by eating iron-rich plants when they suffer from iron deficiency.
After all, we humans are “just” animals, too. Of course, we have elevated ourselves, crowned ourselves, and attributed to ourselves a unique evolutionary path - one that is certainly justified.But we cannot deny that, without our minds, we are nothing more than animals. Not in a judgmental sense, but purely from a biological perspective: animals that function exactly as nature intended. Even though we have achieved tremendous social and cognitive development (and this is where the “I” also lies)(in society), our body remains merely an animal bound by the chains of evolution.
This coevolution has even gone so far as to shape our own biology: while strict carnivores typically perceive only a limited color spectrum, we primates and herbivores have developed trichromatic vision. We possess our eyes to precisely identify the plant’s “invitation” - the ripe, lectin-free fruit - amidst the sea of green leaves. Thus, we have learned to align our consciousness with the tree’s “desire.”
The topic raises fascinating questions about intelligence and the systemic order underlying these processes. Even though I view these phenomena primarily through the lens of classical evolutionary biology and natural selection - that is, as the result of a harsh optimization process spanning millions of years - I share Bayani’s admiration for the precision of these biological networks.
The Plants' Weapon: Between Fruits and Lectins
Nature offers us numerous interesting examples of complex interactions between organisms. For example, an apple tree produces fruit so that mammals will eat it and spread the seeds through their droppings. This type of cooperation between different species can be observed in many ecosystems. This raises the question of how the apple tree can “know” about the enormous complexity of the mammals that consume its apples.
A study by renowned plant researcher Michal Gruntman empirically documents plants’ “ability to make decisions” when choosing optimal survival strategies. The study on Potentilla reptans shows that, depending on the competitive situation, plants selectively switch between three strategies: confrontational vertical growth, shade tolerance, or lateral avoidance. These responses demonstrate that plants “choose” one of several alternative plastic responses in a way that best suits the prevailing light-competition scenarios.
The Max Planck Institute for Chemical Ecology is also researching how plants actively respond to their environment and form complex networks. This increasingly challenges the notion of isolated, “blind” evolution. One could argue that producing an apple with the perfect composition for the target organism involves more than simple mutation and natural selection. This would require a “awareness” of other living beings, a “consciousness” that extends beyond itself. Modern botany is increasingly recognizing this plant intelligence.
In conventional biology, such phenomena are explained exclusively through mutation and selection. While this perspective is correct within its own framework, it falls short when nature is understood as a “collective self” or as “immanent intelligence.” If we theoretically assume that there is such a thing as a “collective natural consciousness” that sets the framework within which biological adaptations and decisions can take place in a purposeful manner, much could be explained. These terms do not explain the phenomenon precisely and serve only as a point of reference, since plants do not possess consciousness as we conceive of it and, of course, do not feel pain when we consume them.
While classical natural science often describes evolution as a purely chance-based process, the precision and synergy of these processes suggest an intelligence inherent in the system. Statistical chance alone can hardly adequately explain the high degree of organization in life. Without this structuring function, evolution would run the risk of stagnating in blind chaos. Every life form would remain isolated.
According to this hypothesis, the apple would have evolved not only through random mutations and passive selection, but also through emergent self-organizing processes within complex ecological networks. The remarkable fit between the fruit and its consumer could point to systemic feedback loops in which the exchange of information between organisms leads to coordinated patterns of development.
In any case, we can say with certainty that natural selection is certainly not a “blind” coincidence. The chance that acts as the architect of life here is not only intelligent but also a master of precision, as nature’s marvelous creations repeatedly demonstrate.
From a philosophical perspective, this beauty is not merely a human perception born of a social instinct for survival, but rather a reflection of our very essence.
The Struggle for Survival - The Weapon of Plants
In nature, there are various types of plant-based foods, which we broadly categorize as fruits and vegetables. While many parts of plants that we classify as vegetables often protect themselves with lectins and other defense compounds, fruits have evolved as a means of attracting animals to help disperse their seeds. Through natural selection, the plant or tree has developed an attractive offering that serves to disperse its seeds.
In doing so, the evolutionary process has created an irresistible offer. Fruit contains a lot of fructose, which provides quick energy and was in short supply during the Paleolithic era. The brain therefore rewards us with dopamine surges when we eat fruit. Although we no longer notice this as clearly today, since the brain has developed a new tolerance threshold due to refined sugar, this evolutionary adaptation was successful. However, fruit contains not only sugar but also numerous other plant compounds and antioxidants that are apparently well-suited to our bodies.
A study by Avena et al. (2008) demonstrates that sugar activates dopaminergic reward pathways in the brain and leads to neuroadaptive changes with repeated exposure. The research shows that refined sugar triggers stronger dopamine releases than natural sugar sources, thereby shifting the reward threshold. Modern highly processed sweeteners "hijack" evolutionarily developed reward mechanisms that originally served to identify nutrient-rich fruits.
However, there is also the other side of the coin: plants that are not interested in cooperation at all and often aggressively protect their seeds and kernels. It is no coincidence that flax owes its name to this. Even people in ancient times recognized that it is potentially toxic due to its cyanide-containing seeds and gave it the name “common” flax. Furthermore, even further back, in the Paleolithic era, it was not yet common to consume large quantities of legumes, as is the case today. As such, they are considered the leading source of lectin-containing foods and are difficult to digest, since the body has not optimally adapted to digesting them. When raw, beans are even considered toxic, and their consumption is strongly discouraged.
A study by Cordain et al. (2005) documents that lectins in legumes represent evolutionary defense mechanisms and can cause gastrointestinal problems in humans, as these foods have only been consumed regularly since the Neolithic period (approximately 10,000 years ago). Research shows that the relatively short evolutionary adaptation period was insufficient to develop full tolerance to antinutritional factors such as lectins, saponins, and protease inhibitors. Raw kidney beans, for example, contain toxic amounts of the lectin phytohemagglutinin, which triggers severe symptoms of poisoning even in small quantities.
Lectins can be particularly problematic for patients with psychosomatic complaints. While peeled and seeded tomatoes pass through the intestines without issue, unpeeled tomatoes can trigger psychosomatic reactions. This is because the human subconscious - "unconscious thinking" - combined with the irritated intestinal reaction leads to severe symptoms. Observations have shown that psychosomatic reactions are controlled by the subconscious. The body is very often (or almost always) involved, but it is the psyche that gives the “green light.” The body asks, “Is this bad?” - referring to the irritation in the gut - and the psyche answers with a “yes,” whereupon psychosomatic symptoms arise. However, since most people do not have such deep access to their own inner selves, the first step is to avoid such triggers.
A lectin-free diet can also benefit people who feel lethargic or have general health limitations. When we consider the body and the era in which it still believes it is living - the Paleolithic era - lectins become all the more relevant. Many of the vegetables we eat today are modern cultivars or were only recently discovered. The body hasn’t had enough time to adapt to the substances they contain, especially lectins. Therefore, it’s not surprising that legumes (including cashews, which aren’t even nuts botanically speaking), whole grains, and many other vegetables can cause significant damage to our bodies.
Ultimately, as human beings, we must ask ourselves why we do not avoid all these burdens and why we care so little about our diet, even though it is the very thing that sustains us. The uncomfortable truth is that our diet shapes us significantly. It is not merely relevant or important; it fundamentally shapes who we are. We are, to a significant extent, what we eat. A wild animal would probably think that we took a wrong turn in evolution, because we have “dumbed down” when it comes to our diet.
We use the body’s reward mechanisms primarily as a tool for pleasure, rather than as a guide. Now, onions or healthy vegetables taste “boring.” Only when we trick the body with enough salt, sugar, and flavorings do we get the “taste” we prefer. In doing so, we as a species have turned evolution on its head, because we have decided not to prioritize survival, but rather to seek pleasure above all else. Perhaps we would have been more successful if we had not only hijacked the reward systems but also combined them with actual nutrients.
The good news: Lectins can be deactivated
According to Dr. Gundry, lectins can be largely deactivated by heating them in a pressure cooker at 15 PSI (about 121 °C) for 15 to 30 minutes. The plant had prepared itself for many predators, but certainly not for a human with a pressure cooker.
Lectins and phytates, which are found primarily in whole-grain products and legumes, can interfere with the absorption of important minerals such as iron and magnesium. This can be particularly problematic for people with iron deficiency.
Lectins employ various strategies: Some confront us directly - they irritate the intestinal lining and challenge our digestive system. Others adopt a more subtle approach: “You’re expecting nutrients? But I’m actually depriving you of yours.” They specifically bind the minerals that were already considered precious resources by our ancestors and are essential for our survival - iron, zinc, and magnesium.
Given the many nutrient-depleting factors, it is not surprising that intracellular magnesium levels are out of balance in many people and cannot be quickly detected by a simple serum blood test.
Lectins exhibit a remarkable variety of biological activities that go far beyond simple carbohydrate binding. Their primary mechanisms of action include disruption of the intestinal barrier function, chelation of essential minerals (iron, zinc, calcium), and modulation of immune responses through the activation or suppression of specific signaling pathways. Furthermore, lectins can act as enzyme inhibitors, interfere with hormonal signaling cascades, influence cell adhesion processes, and trigger autoimmune reactions through molecular mimicry. These multifactorial properties make lectins potent bioactive compounds with both protective and antinutritional effects.
At the same time, studies show that certain plant lectins can also have positive effects when used therapeutically. For example, they can influence the immune system or even act against cancer cells. For this reason, they are being investigated in research as potential tools for diagnostics and therapy, among other applications.
Dr. Gersch is a leading specialist on lectins in the German-speaking world. In his practice in Kaiserslautern and on his website, he explains that a lectin-free diet has a positive effect on autoimmune diseases, celiac disease, gluten intolerance, digestive problems, and allergies. He has gained many years of experience in his practice and demonstrates the importance of a holistic approach that also takes into account the defense mechanisms of our food.
Dr. Gersch also has extensive practical experience with patients who have experienced positive health outcomes. This is based on his in-depth understanding of biological interactions and holistic treatment approaches.
Such in-depth medical knowledge is particularly valuable when we view the human body as an evolutionarily developed system whose functioning has not yet been fully explored. Modern medicine is continually expanding its understanding through innovative approaches and new findings.