Pequenos Desafios, Grandes Ganhos: A Ciência da Adaptação

When we travel to high altitudes, such as the Andes Mountains, for example, we face a series of challenges: difficulty breathing, fatigue, headaches and other unpleasant symptoms. This occurs due to decreased atmospheric pressure, which results in less oxygen being available in the thin air. But what about the people who live there, why don't they experience these discomforts?

The answer lies in the human body's incredible capacity for adaptation and survival . In this case, to deal with the lack of oxygen, the body triggers a series of physiological adaptations with the aim of maintaining adequate oxygenation in all cells. In response to this condition, the kidneys increase the production of erythropoietin, a hormone that signals the bone marrow to produce more red blood cells.

Red blood cells are the cells responsible for transporting oxygen from the lungs to the body's tissues and returning carbon dioxide from the tissues to be exhaled through the lungs. As the number of red blood cells increases, the blood's ability to carry oxygen improves. Then, after a while, the body adapts to the altitude, the symptoms disappear.

This not only helps the body adapt to altitude, but can also improve oxygen transport under normal conditions, offering potential benefits such as improved physical endurance and energy efficiency. There are countless situations that trigger survival and adaptation mechanisms in the human body, however, not always with beneficial results at first glance. The experience of astronauts on space missions, in the vastness of space, far from the Earth's gravitational pull, is an example of this.

The body is in a state of microgravity; there, muscles and bones face drastically reduced demand. The body interprets the lack of constant use of muscles as a new normality. In response, an adaptation process begins; From a biological point of view, maintaining muscle mass and bone density is metabolically expensive, requiring a large amount of energy and resources, such as proteins and minerals.

Thus, in microgravity, the body begins an optimization process, reducing what it identifies as dispensable tissues. In this case, muscle mass that is not being used and bone density that is not needed to bear weight are reduced. The body reduces the production of muscle and bone cells, conserving energy for other functions.

To combat this loss, astronauts perform specific exercises on the space station, but even so, the loss of muscle mass can reach 5% per week, and the loss of bone density can reach a rate of 1% per month. While this adaptation makes sense in a microgravity environment, it becomes a problem when astronauts return to Earth; which is why, upon return, astronauts need a period of rehabilitation to rebuild muscle strength and bone density. Such adaptations highlight an interesting truth about our existence: we are profoundly shaped by the environment in which we live.

Earth's gravity, for example, a constant force that we rarely consider in our daily lives, plays a crucial role in defining the structure and functions of our bodies. Let's think a little more: if the intensity of gravity were greater or lesser, perhaps we would be completely different beings than we are today. This is because the Earth's gravitational force, measured at approximately 9.

8 m/s², not only shapes our physical structure, but also profoundly influences different aspects of our organism. For example, gravity plays an important role in blood circulation, which could change blood pressure and even the shape of the heart. Growth hormone and cortisol, crucial for controlling stress, growth, and metabolism, could also have different secretion rates if the Earth's gravitational pull were different.

But beyond gravity, sunlight can also directly shape us in many ways. For example, our circadian rhythms, vitamin production and immune system modulation are directly influenced by the amount of oxygen available in the air we breathe, which has profound implications for our physiology. Variations in Earth's atmospheric composition over geological eras have shaped the evolution of living organisms, including humans.

Thinking about it may seem pointless, but it can bring us important insights into our human condition and a deeper understanding of the aspects that involve our health and well-being. These examples highlight the incredible capacity that the human body has to fight for survival, creating adaptation and strengthening mechanisms in the face of challenges. It is in this context that an old concept resurfaces with the power to revolutionize our understanding of health and well-being: hormesis.

The concept of hormesis has been recognized and explored by several scientists over the years in different areas, having diverse historical roots. However, it is often attributed to the German pharmacologist Hugo Schulz, who in 1888 made important discoveries in this regard. Schulz noted that minute amounts of disinfectants could, paradoxically, stimulate, rather than reduce, yeast growth.

From this observation, he formulated the idea that small doses of a substance or condition can stimulate a beneficial response in an organism, while large doses can be harmful. Our first example, the one where we talk about adapting to thin air, perfectly illustrates the concept of hormesis. On the other hand, the example of astronauts presents a very different scenario: the absence of gravitational stress does not drive the body to strengthen; on the contrary, it leads to a reduction in physical capabilities due to lack of stimulation.

Hormesis, therefore, is not simply about adaptation, but about how mild stressors can trigger positive responses of strengthening and resilience in the organism. You don't have to look far to find examples of hormesis in action. Plants exposed to small amounts of toxins develop greater resistance to pests and diseases.

The human immune system offers another interesting example of hormesis in action: It's natural to think of bacteria and viruses as threats to our health, and in fact, there are many dangerous microorganisms. However, hormesis offers us a different perspective: controlled and moderate exposure to these agents from childhood is essential for the development of a robust and adaptive immune system. The immune system needs to learn to differentiate between real and harmless threats.

Over the past few decades, it has been noted that overly sterilized environments and reduced exposure to common microorganisms can contribute to an increase in allergies, asthma, and other autoimmune diseases. This is because the immune system, in the absence of mild natural stressors, can become hyperreactive to harmless substances such as pollen or certain foods, treating them as if they were serious threats. This phenomenon highlights the importance of balancing exposure and protection; While cleanliness and hygiene are fundamental to preventing infectious diseases, a certain degree of exposure to microorganisms is beneficial and necessary for the development of a healthy and effective immune system.

But to further understand the concept of hormesis and adaptation, we need to return to the example of lean mass and bone density: while the absence of gravity in space leads to a decrease in lean mass and bone density, here on Earth we can employ the concept, only than in the opposite way. And how to do this? It's simple: although we can't change the planet's gravity, it is entirely possible to increase the tension on our muscles and bones through weight exercises.

When we impose additional load or tension on muscles through strength training, the body interprets this pressure as a stressor and therefore the need to adapt in response to this challenge. A cascade of biochemical and physiological processes is triggered, which then begins the repair of muscle microdamage caused by exercise. At the same time, the body increases the synthesis of muscle proteins, strengthening and increasing the volume of the muscles involved.

A process supported by hormonal signals such as increased testosterone and growth hormone, essential for muscle growth. Furthermore, the pressure exerted on the bones during weight exercises triggers what is known as bone adaptation: osteoblasts, cells responsible for the formation of new bone tissue, become more active in response to mechanical stress, resulting in thicker bones. dense and strong.

This phenomenon not only improves bone strength, but is also crucial in preventing conditions such as osteoporosis. Intermittent fasting is another practice that perfectly illustrates the principle of hormesis. The temporary absence of food intake signals the body the need to adapt, triggering a series of physiological responses that not only help to deal with the fasting period, but also promote improvements in hormonal regulation and optimization of energy metabolism.

Furthermore, during fasting, the decrease in available energy stimulates autophagy, allowing the body to rid itself of parts of cells that are not functioning properly. This contributes to cellular health and disease prevention. Therefore, intermittent fasting, well managed, works as a kind of small stressor that makes the body create adaptation and strengthening mechanisms.

Even fasting, which is a hormetic stimulus, has to be at the right dose, as the dose has the effect; So, too much is not good. I receive several patients in the office that I reduce the fasting hours. Do you know why?

Because we're not talking about prolonged stress here; Stress needs to be acute and short-lasting. So, fasting too much ends up not being acute stress, you stay constant, and you no longer gain. So, what we're talking about here, folks, is short stresses that bring benefits.

The dose makes the poison: excess food, eating several times a day, the frequency is completely harmful to our health because we don't give the organelles that are sick a chance to renew. So this is an excess that brings no benefit. Now, if you fast for too long, you also don't have the nutrient supply window phase to build what's needed.

That's why we need to have a strategy drawn up according to our needs. A person with diabetes, with a lot of central obesity, and with an accumulation of visceral fat, will need to fast much more than a person who is seeking fasting for prevention or for mental improvement. Another interesting example of hormesis is related to the presence of bioactive compounds present in vegetables.

Although bioactive compounds are not classified as essential nutrients, they play interesting roles when interacting with our body. Originated as defense mechanisms against external threats, such as insects, parasites, bacteria, and fungi, these compounds, when consumed by us, act by provoking some physiological responses in our bodies. While some have antioxidant and protective properties, others are known as antinutrients and can interfere with the absorption of essential nutrients if consumed in excess.

In other words, excess can have negative effects, as can excessive exercise without adequate rest, or prolonged fasting without considering acceptable limits. But this is where the concept of hormesis fits in: moderate and balanced exposure to such compounds puts the body in a situation of adaptation and strengthening, reducing sensitivity and allergies. However, it is essential to recognize that hormetic stress, while positive for many people, can represent excessive stress for those dealing with certain health issues.

In this context, it's worth talking about an example of food hormesis: let's talk about broccoli. Although this vegetable is known for its nutritional properties, it also contains antinutrients such as glucosinolates, progoitrins and oxalates. These substances can interfere with mineral absorption and thyroid function, but here comes the hormesis paradox: a moderate dose of these components activates the body's ability to adapt and strengthen itself.

When broccoli is chopped or chewed, a chemical reaction occurs that transforms glucosinolates into sulforaphane. sulforaphane is a stimulator of the body's antioxidant system; This compound not only enhances the immune system, increasing defense against infections, but also stimulates cellular action mechanisms that can neutralize harmful agents. Although the antinutrients in broccoli may seem undesirable at first glance, within the concept of hormesis, controlled exposure can actually induce adaptive and strengthening responses.

One thing related to diet and eating routine that was a surprise to me when I started looking into this is that diet-related hormesis comes from aggression as well. We have the reasoning that vegetables are healthy because they offer micronutrients, vitamins, and minerals; This may be true, but there was one doubt that the bioavailability of vegetable micronutrients is not that good for humans. So why would vegetables be associated with better cancer and disease outcomes?

In fact, today there is an area that is studying the issue of the hormetic effect of small plant aggressors, which are phytochemicals. The most common ones, such as curcumin from turmeric, resveratrol, and the isocyanates found in cruciferous vegetables such as broccoli and cauliflower, do not give us health by offering us nutrients, in fact, they harm us in a certain way, and the metabolic response This aggression is an antioxidant and anti-inflammatory effect from which we benefit. We, humans, have gone through a long period of evolution and physical and metabolic adaptations, and we continue to adapt to external factors so that we can live better in our environment and in our diet as well.

There was a lot of adaptation: at the beginning of our evolution, we fed on carrion, the remains of other animals; Then, we started hunting and the fire came, and then the plantation. Today, we are omnivorous beings, which means that we can eat both animal and plant foods. To further illustrate hormesis in a dietary context, let's turn our attention to teas, which are rich in tannins, such as black tea and, to a lesser extent, green tea.

Tannins, although they can bind to and inhibit the absorption of certain nutrients such as minerals, illustrate the paradox of hormesis: they also play a beneficial role by inducing microdamage that promotes an adaptive response in the body. Through regular consumption of these teas, the body is stimulated to activate antioxidant mechanisms and detoxification processes, reinforcing the body's health in several aspects. It is important to emphasize that hormesis is dose-dependent.

Which means it's crucial to find balance in your tannin intake to obtain their hormetic benefits without causing negative health side effects. In other words, small doses offer hormetic benefits, while excessive consumption can be harmful. And this also applies to coffee, which, although it contains tannins in smaller quantities, follows the same principle.

We all have metabolic individualities, and this needs to be taken into account in nutritional management. Nutrigenetics already shows us the impact of each food on our DNA. When we talk about bioactive compounds present in fruits and vegetables, there is no doubt about their benefits in longevity and disease prevention, because of their antioxidant effects.

But needs and quantities need to be assessed individually so that these bioactive compounds can perform their functions, and we cannot forget that to be healthy we don't need to be literal; We have to respect the metabolic individuality of each patient. We could stay here for hours talking about our body's incredible ability to adapt and strengthen itself in the face of the most varied stimuli. However, we will highlight just two additional examples to further illustrate this capability.

Let's start with a factor that is as everyday as it is powerful in its ability to shape our physiology: temperature. Imagine what happens when we expose ourselves to the cold, like in an ice-cold bath, or when we let ourselves be enveloped by the heat of a sauna. Initially we felt discomfort, but it is exactly at this moment that the spectacle of the adaptation begins.

Intense cold activates our energy reserves, stimulates the immune system and increases blood circulation. Furthermore , it prepares the body with several positive adaptations, strengthening it against future challenges. Likewise, extreme heat triggers the production of heat shock proteins that protect cells against stress and promote detoxification through sweat.

These responses are not just survival mechanisms; they are true strengthening processes. It is important to emphasize that exposure to extreme temperatures must be practiced in a controlled and gradual manner, in order to allow the body to adapt without causing damage. Following the principles of hormesis, in the north of our world, the Nordic countries study saunas and cold baths a lot because they even go by boat; the boats have a sauna and, then, everyone stays on the boat and then they jump into the freezing sea.

Why ? Because there the incidence of depression is very high and they have very little sun exposure. Unlike them, we have a lot of sun; We have no shortage of sunshine all year round, and the sun is also a very important stimulus for our mood.

But either way, it's important that you know. So, I have patients with depression who I say, look, you need to find a way to provide this type of stimulus. Why?

Because it has an impact on mood and is being studied as an antidepressant strategy. So, exercise also has a series of meta-analyses already on exercise in the treatment of depression, in the treatment of obesity; So, exercise, cold baths, sauna are extremely important for this. And then, patients who are unable to exercise due to some cardiovascular restriction are also studying the hormetic effects of the sauna to replace exercise for these patients who are not as cardiovascularly prepared.

Hormesis, in its broadest concept, encompasses not only the adaptation and strengthening of the body, but also the mind. In the field of Psychology, hormesis suggests that facing challenges, problems, and mild to moderate adversities makes us better able to deal with greater stress, promoting personal and emotional growth. While the examples we mentioned illustrate the incredible ability to adapt and strengthen our body and mind, it is essential to reflect on limits.

We need to recognize that not all stress is equal, and not all challenge brings hormetic benefits. There is a fine line between what challenges and what destroys; Habits such as consuming soft drinks or foods rich in trans fats are not ways to stimulate our resilience, on the contrary, they are choices that lead us to a cycle of cumulative damage. Understanding this distinction is vital to following a path that strengthens us and not the other way around.

May this understanding and these reflections lead us to continuous growth, may we be willing to look beyond the immediate and recognize the inestimable value of a life lived with wisdom, purpose, and resilience.