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The Plant's Weapon: Between Fruits and Lectins

Unripe apples are toxic; ripe fruits are an invitation. How plants strategically deploy chemical weapons - and shaped human perception in the process.

First published: 03/18/2026 DOI: 10.66670/iqverse.2026.0015

Navid Bayani, Christian Gersch (MD)

This article was written by multiple authors. The participation of a medically or otherwise professionally qualified co-author does not constitute a professional endorsement or validation of statements made by other authors.

Disclaimer: This article does not replace professional medical advice. The perspectives presented serve solely as a supplementary source of information. Scientifically unsubstantiated statements should be understood as hypotheses. Errors are possible.

Paper (PDF)

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 did nature actually intend it to be?

In my daily practice, I see the biochemical consequences of what Navid Bayani so vividly describes in this article. 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” that plants use to protect their vital organs (leaves, stems) and their offspring (seeds).

What’s particularly fascinating is the dichotomy between defense and invitation that we observe as fruit ripens: An unripe, green apple is full of lectins and hides 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 you shouldn’t pick them prematurely in May, but must wait until September -by then they’re ripe, lectin-free, and digestible.

This coevolution has even gone so far as to shape our own biology: While strict carnivores usually perceive only a limited color spectrum, we primates and herbivores have developed trichromatic vision. We have our eyes to precisely identify the plant’s “invitation” -the ripe, lectin-free fruit -amidst the sea of green leaves. In this way, we have learned to align our consciousness with the tree’s “desire.”

This publication raises fascinating questions about the intelligence and 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 rigorous optimization process spanning millions of years -I share the admiration for the precision of these biological networks.

Bayani succeeds here in bridging the gap between botanical strategy and our modern diet. His text encourages us to view the food on our plates not merely as calories, but as the result of complex interspecies communication.

The Weapon of Plants: 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 disperse the seeds through their excrement. 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 of 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 “select” 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 it takes more than mutation and natural selection to produce an apple with the perfect biological composition for the target organism. While the explanation of millions upon millions of iterations over millions of years points to adaptability, it remains a mystery to human observational capacity, which cannot acknowledge a “higher, collective natural intelligence” as the cause of the diversity of natural selection and the interconnectedness of all living beings. The “All-Seeing Eye of Evolution,” which governs life and ultimately represents the highest authority over life -an authority from which not even humans can escape.

While the perspective of conventional biology is correct within its own framework, it falls short when nature is understood as a “collective self” or “immanent intelligence.” If we theoretically assume that there is such a thing as a “collective consciousness of nature” that sets the framework within which biological adaptations and decisions can take place in a purposeful manner in the first place, this would explain a great deal.

While traditional science often describes evolution as a purely random process, the precision and synergy of these processes suggest the existence of an intelligence inherent in the system. Statistical chance alone can hardly adequately explain the high degree of organization found in life. Without a 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-organization processes in 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, it can be said with certainty that natural selection is not a “mindless” coincidence. The apparent coincidence -which adapts selectively yet arbitrarily in order to survive, thereby assuming the role of the architect of life -is evidently not only intelligent in and of itself but also a master of precision. This is brought home to us time and again by the marvelous works of nature.

From a philosophical perspective, this beauty is not merely a human perspective born of the instinct for survival, but rather a reflection of our own inner core.

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 plant parts that we classify as vegetables often protect themselves with lectins and other defense compounds, fruits have evolved as a lure to facilitate seed dispersal.

In the process, this evolutionary process has created an irresistible offer. For example, 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 -the reward mechanisms continue to function. Fruit also contains not only sugar but also numerous other plant compounds and antioxidants that appear to be 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 greater dopamine release than natural sources of sugar.

However, there is also the other side of the coin: plants that are not at all interested in cooperation and often aggressively protect their seeds and kernels. It is no coincidence that flax owes its name to this trait. Even people in ancient times recognized that it is potentially toxic due to its seeds containing hydrocyanic acid, and gave it the name “common” flax. Going even further back, in the Paleolithic era, it was not yet common to consume large quantities of legumes, which also employ a seemingly aggressive defense strategy. They are considered the leading source of lectin-containing foods, are difficult to digest, and the body has still not optimally adapted to digesting them. When raw, beans are even toxic, which is why consuming them 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, since these foods have only been consumed regularly since the Neolithic period (approximately 10,000 years ago). Research shows that the relatively short period of evolutionary adaptation was insufficient to develop complete tolerance to antinutritional factors such as lectins, saponins, and protease inhibitors. Raw kidney beans, for example, contain toxic levels of the lectin phytohemagglutinin, which can cause severe symptoms of poisoning even in small amounts.

Lectins can be particularly problematic for patients with psychosomatic symptoms. While, for example, a peeled and seeded tomato passes through the intestines without any problems, an unpeeled tomato can act as a “somatic trigger.” This is because the human subconscious, in combination with the irritated intestinal reaction, leads to psychosomatic chain reactions. In this case, it often takes nothing more than the association of negative thoughts with the tomato and the actual stress caused by the lectins.

Observations have shown that psychosomatic reactions are controlled by the subconscious. The body asks, “Is this serious?” -referring to the irritation in the intestines -and the unconscious mind responds with a “yes,” whereupon psychosomatic symptoms appear. However, since most people lack deep access to their inner selves and are unaware of these channels of communication between the body and consciousness, it is often difficult for those affected to identify the causes of their psychosomatic distress.

A lectin-free diet can benefit people who feel lethargic or have general health limitations. When we think back to the time when the body still believed it was living in the Paleolithic era, lectins become all the more relevant. Many of the vegetables we eat today are modern cultivars or were discovered only recently. The body hasn’t had enough time to adapt to the substances they contain, especially lectins. Despite these circumstances, vegetables remain among the healthiest foods and should always be part of our diet.

The Underestimation of Healthy Eating

The uncomfortable truth is that our diet has a profound impact on us. It is not merely “relevant or important” -it fundamentally shapes who we are. We are, to a considerable extent, what we eat. To put it figuratively, a wild animal would probably think that we’ve taken a wrong turn in evolution, because we’ve literally “become dumber” when it comes to our diet. This is truly ironic, since one might assume that Homo sapiens, given the vast variety of food available, would now be consuming the best foods with the best nutrients. Driven by our natural sense of hunger and the instinct that knows exactly what, when, and how much we need to eat. However, since we primarily reach for foods that only reinforce addictive behaviors and, in modern times, serve no purpose other than to provide a misguided sense of happiness, this reveals the extent of an evolutionary mismatch.

We use the body’s reward mechanisms primarily as a means of seeking pleasure, rather than as a guide. For example, fruit or healthy vegetables now taste “boring.” Only when we trick the body enough with salt, sugar, and artificial flavors do we get the “taste” we prefer. In doing so, we as a species have turned evolution on its head, because we have chosen to prioritize pleasure over survival. Even though survival and pleasure certainly represent a reciprocal dynamic in nature, this balance has been upset in modern times and manifests itself in numerous diseases.

The good news: At least the lectins can be deactivated

Even if we can’t yet tame our crazy, dopamine-addicted brains and have to reach for coffee every morning, at least the lectins -according to Dr. Gundry -can be largely deactivated if they’re heated in a pressure cooker at 15 PSI (about 121 °C) for 15 to 30 minutes. The plant may have prepared itself for many predators, but certainly not for a human with a pressure cooker.

Lectins and phytates, which are found primarily in whole grains and legumes, can also impair 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 mucosa and challenge our digestive system. Others employ a more sophisticated tactic, specifically binding the minerals that were already considered precious resources by our ancestors and are essential for our survival, such as iron, zinc, and magnesium. It is certainly no coincidence which nutrients are targeted; rather, it is a clear sign that the plant knows its consumer very well and is prepared for it.

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 assessed through a simple serum blood test either

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 combat cancer cells. For this reason, researchers are investigating them as potential tools for diagnosis and treatment, among other applications.

Dr. Gersch is a leading specialist in lectins in the German-speaking world. In his practice in Kaiserslautern and on his website, he explains that a lectin-free diet can have 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 body’s defense mechanisms against food.

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 understood. Modern medicine is continually expanding its understanding through innovative approaches and new findings.

References

Max Planck Institute for Chemical Ecology, Jena - Plant diversity shapes chemical communication in ecosystems https://www.mpg.de/26012744/plant-diversity-shapes-chemical-communication-in-ecosystems
Dr. med. Christian Gersch - Bei welchen Erkrankungen ist eine lektinfreie Ernährung sinnvoll? https://www.drgersch.de/patienteninformationen/gegen-welche-erkrankungen-eine-lektinfreie-ernaehrung-helfen-kann

This article is based entirely on the author's own experience and expertise. Where AI tools were used to generate supplementary text from the author's input, these passages are clearly marked as quoted blocks.

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Autoimmune disease diet Gut health lectins Fruit ripeness nutrients Legumes digestion Human plant coevolution Lectins nutrition Lectin-free diet Natural selection plants Plant intelligence evolution Plant defense mechanisms

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