Scientific Approach to Nutrition

A scientific approach helps distinguish between well-substantiated findings, preliminary conclusions, and mere conjecture. Finding a single study is not enough—the quality of the evidence, its proper interpretation, and the ability to translate general insights into recommendations for a specific individual all matter. It is the combination of scientific evidence, professional judgment, and individual needs that forms the foundation of meaningful nutrition practice.

Experts and laypeople around the world are continuously debating what a properly set dietary regime should look like. The "wiser" ones agree that it should correspond to the individual requirements of each person. Thus, every person should eat in a distinct manner. This claim sounds good on a theoretical level, but its real-world application is another matter.
The fundamental problem lies in how we should evaluate these individual needs of the body. Essentially, there are two diametrically opposed approaches:

The first, historically rooted and so-called "natural" approach, is based on long-term observation of the body's behavior in various situations, which we then try to interpret in our specific way. Besides requiring knowledge of human anatomy, metabolism functioning, and practical experience, it's neither complex nor demanding. By observing stool quality, neuromuscular coordination, stress expressions, hair, nail, and skin quality, and many other indicators, we can assume (= not know) what's happening in the body at the level of metabolic processes and simultaneously how the organism reacts to nutritional quality.
This system is based on observation, feelings (intuition), experience, and estimates. Thus, its precision level is highly debatable. However, this is a view of relative value, because proponents of these methods have an ace up their sleeve in the form of the fact that biological processes in living organisms are dynamic, flexible, adaptable, and effectively as a whole unquantifiable. And they are right in this respect because whatever we measure in a living organism using any analytical method is just a reflection of its current functioning state. It tends to change with every moment, and in the vast majority of cases, each body part submits its behavior and manifestations to the rules of the whole. For example, systems of Ayurveda or traditional Chinese medicine have been functioning this way for millennia.

Yet it's no surprise that a significant part of the population naturally tends to focus their attention on more precise diagnoses and ensuing eating systems. The second approach, which evaluates metabolic processes, aims to be as precise as possible. It's typically analytical, known as modern scientific. It is based on principles of skepticism that current science has set as the foundation for its functioning. That is, from the quote attributed to French philosopher Descartes - "I doubt, therefore I think, I think, therefore I am."
Modern science has established certain rules, where among the basic ones are:

1. Knowledge.
The ability to truly demonstrate that what we study is based on knowledge, not assumptions. A scientist is someone whose task is to delve deeper and deeper into the essence of the problem they are studying through rational cognition. These objective findings are then formulated using logic into specific concepts, theories, and laws. According to scientific rules, there is no room for any subjective assumptions.

2. Questioning.
The process of questioning is the driving force for progress because questioning anything - even newly discovered facts - helps uncover further perspectives on the issue. Science itself originated from philosophy, which is a platform for contemplation allowing for the questioning process and the posing of questions that push the level of understanding further.

3. Repeatability and Measurability.
Every result must be verifiable. If a scientist finds that a heightened intake of fiber leads to better intestinal function, it must be possible to replicate this conclusion in other groups of people, under different conditions, and ideally by other researchers. Only then is it considered evidence, not a random occurrence. Measurability means that we have clearly defined indicators (for example, blood sugar level, blood pressure, or BMI) and know how these values change depending on the diet examined. If one laboratory finds a positive effect but another does not confirm it using the same methodology, we need to reassess the result. In practice, this means that advice like "this tea definitely burns fat" has no scientific value until it is supported by repeated and measurable results.

4. Transparency and Control.
In science, it's necessary to publish results and allow other experts to verify and possibly dispute them. Hence, studies are published in scientific journals and undergo what's called peer review. If, for instance, someone claims that a particular dietary supplement aids in weight loss, their own assertion or their clients' experiences are insufficient. They must provide precise data and allow for independent evaluation. A case in point could be when a manufacturer promotes a protein shake as a "scientifically verified muscle growth aid." But if results come only from one company study without independent control, the scientific community does not regard it as evidence.

5. Ethics.
Every research must respect the health and dignity of participants. In nutrition, this means, for example, that we cannot subject a group of people to a diet that demonstrably harms them long-term just to confirm a hypothesis. Similarly, participants must always be informed about what they are participating in and have the right to withdraw anytime. In practice, it would be unethical, for example, to forbid a group of people from consuming fruit entirely for several years just to see if their cancer risk increases. Ethical committees, therefore, always assess whether the research benefits outweigh the risks.

An important term used in connection with the modern scientific approach is the evidence-based approach. It means that a professional relies not on a single study or personal impression but on the best available scientific evidence and verified knowledge available. In the health sector, this approach is known as Evidence-Based Medicine (EBM), or medicine based on evidence, which allows distinguishing between truly effective recommendations and mere popular trends without data support. Those who work with EBM rules and principles should not rely only on numbers and statistics. The expert's experience plays an important role along with the individual needs, preferences, and capabilities of each person the resulting recommendations should apply to. [1] [2] The reason is that data from expert studies focus on populations, not individual persons - population norms need not necessarily meet an individual's needs.

Based on such gathered evidence, official nutritional recommendations are formulated. These are issued by, for example, the World Health Organization (WHO), the European Food Safety Authority (EFSA), or national expert societies. These recommendations are not dogma but rather a reflection of the current scientific consensus. Therefore, they change over time - what was valid thirty years ago may be outdated today.

Part of the scientific approach is also the ability to critically work with information. In practice, this means that we should be able to differentiate between what is a serious scientific evidence and what is merely a pseudoscientific claim or marketing manipulation. Not every published information has the same value. A quality study is based on a clearly defined methodology, has a sufficiently large number of participants, takes place over a longer period, and its results are repeatable in other research. On the contrary, pseudoscientific claims typically rely on a single source, a very small sample of people, or just an individual's experience ("I tried it, and it worked").

This connects to the knowledge of the so-called hierarchy of evidence, which states that a single person's case study has less weight than a randomized controlled trial, and that again has less weight than a systematic review or a meta-analysis. Only knowledge of this pyramid allows for proper evaluation of whether a given piece of information is reliable. When, for instance, someone claims that "coconut oil is a miraculous weight loss remedy," it is our role to verify whether this information comes from quality clinical trials, or just individual observations without broader validity.

Media also play a significant role, often simplifying or distorting scientific study results. Headlines like "chocolate extends life" or "wine is healthier than exercise" attract readers but rarely reflect the actual study content. Usually, it is an extracted detail hotly inflated by the media. It's therefore necessary to learn to read between the lines, seek original sources, and critically evaluate whether the given outcome truly has practical significance.

The scientific approach itself is essential because it can uncover facts leading to knowledge. In an attempt to apply scientific knowledge through the scientific approach to biological systems' behavior (i.e., metabolism manifestations, health, or diet-health relationship), it hits a fundamental problem in the form of the inability to find a key that would allow connecting a massive amount of partial information into a functional whole.

It is important to emphasize that the power of scientific knowledge is not only grounded in principles but also in the types of research methods used. In nutrition, we encounter several basic categories of studies:

- Observational (observational) studies.
Researchers monitor large groups of people, their eating habits, and health outcomes without intervening directly. For instance, they might find that people who consume a lot of fruits and vegetables have a lower incidence of heart diseases. These studies reveal correlations but cannot with certainty say that it's precisely fruits and vegetables causing this because these people might exercise more or smoke less. So, they can effectively identify potential risk or protective factors but cannot confirm them as a cause.

- Intervention studies.
Here researchers actively change some factor. For example, they may instruct one group of people to increase their intake of whole grain foods and not the other. After a few months, they measure differences in cholesterol levels. If the group with whole grains shows better results, it can be said with greater certainty that it was this dietary change that had an effect. The strongest variant is randomized controlled trials (RCT), where participants are divided randomly to avoid bias. An example can be research looking into whether replacing saturated fat sources with plant oils reduces the risk of a heart attack.

- Clinical studies.
These are often used in testing dietary supplements or specific diets. For example, they might examine whether administering omega-3 fatty acids reduces inflammatory markers in the blood of arthritis patients. Their reliability hinges on how many people participate (the more, the better), how long they last (months offer more insight than a week), and whether they are methodologically well-led. Short and small studies can offer only preliminary results, not final proof.

- Systematic reviews and meta-analyses.
These represent the pinnacle of scientific knowledge. They examine dozens or hundreds of individual studies and evaluate them collectively. If most quality studies show that the Mediterranean diet reduces cardiovascular disease risk, we have very strong evidence. Meta-analyses thus form the basis for official recommendations, such as nutritional pyramids or recommended daily nutrient intakes. Unlike a single study, they offer a comprehensive view and reduce the risk of chance errors.

It is crucial for practice to understand that not all studies hold the same weight. If you encounter a newspaper headline "chocolate helps with weight loss," it might be a small study with only a few dozen people where the result could be random. Only when similar results repeat, appear in different countries, and are eventually summarized in a meta-analysis does it make sense to rely on them in formulating recommendations. This is why nutritional recommendations change over time, not as a matter of whim, but as a result of increasingly better and higher-quality evidence. So it's essential to orient oneself in the hierarchy of evidence to protect against hasty conclusions and fashion trends.

Yet, it's necessary to realize that even this highest level of scientific evidence - systematic reviews and meta-analyses - may not always be entirely unequivocal. Different teams of scientists might process identical data differently and thus reach varying conclusions. Additionally, consider the differing quality of individual studies, possible conflicts of interest, and above all the enormous complexity of the human organism and its individual reactions [3] [4]. Therefore, scientific knowledge should be seen more as a dynamically evolving mosaic rather than as an absolute truth.

There’s also a distinction between what scientists can discover and define and how this knowledge is implemented in reality. A typical example is the functioning of the pharmaceutical-medical complex and its inability to address chronic health problems, which many alternative approaches lacking scientific grounding can actually manage quite well.

A significant question is also the connection of science and individuality. Scientific studies always work with larger groups of people and seek universal principles. Thus, we can formulate recommendations applicable to the majority of the population, like how a higher vegetable intake is associated with lower risk of various diseases. However, that's just a general framework. In practice, we face the fact that each person reacts slightly differently. While eating raw vegetables in any quantity is trouble-free for one, another might have digestive issues and needs them cooked. Similarly, someone thrives on a diet higher in grains, whereas another benefits more from proteins from animal sources. A general recommendation like "eat more vegetables" applies to almost everyone, but the specific diet should adjust to one's age, health condition, level of physical activity, cultural practices, and taste preferences. A child needs a different nutrient composition than a senior, an athlete has different demands than someone with a sedentary job, and someone lactose intolerant is unlikely to maintain a healthy relationship with food if forced to eat dairy products just because "science says they are healthy."

Hence, science helps us separate myths from facts, shows direction and provides a solid base for expert recommendations. Yet, it's not enough on its own; it must be supplemented with knowledge of the specific individual, their needs, and possibilities. The challenge is to learn to work with these limits, navigate the quality of evidence and translate scientific knowledge into practical recommendations. This means not only following study results but also considering the client's reality - their health status, financial capacity, time conditions, and simply what they enjoy eating and can sustain long-term.