Keywords

2.1 “Nourishing” Is Wrong

Emeritus Professor Norimasa Hosoya of the University of Tokyo defines “nutrition as the process by which a living organism takes in food from outside the body, uses it, grows and develops, maintains life, and leads a healthy life, and the substances it takes in are called nutrients”. In other words, nutrition is the activity in which our body takes in food and processes it.

However, it is generally used in a confusing way without understanding the difference between “nutrition” and “nutrients”. For example, it is often said that “spinach has nutrition”, but this expression is not correct. Because spinach contains a lot of vitamins and minerals, but not nutrition.

2.1.1 Nutritional Value Depends on the Person

To be precise, spinach contains a lot of vitamins and minerals, so it is a nutritious food for persons who tend to be deficient in these nutrients. It is important to remember that the nutritional value of spinach depends on the type and amount of nutrients it contains, as well as the nutritional status of the person consuming it. Spinach is a valuable food for persons with a low intake of vitamins and minerals, but not for those who consume enough of these. If a person is thin and has a small appetite, rice and fat are better sources of energy than spinach, so these foods are more nutritious. It cannot be said that spinach is a valuable food for all people.

2.1.2 What Are Healthy Foods?

Before and after the war, many people were undernourished due to food shortages. At that time, foods that contained energy and various nutrients and were easy to digest and absorb were regarded as excellent foods with high nutritional value. Yam cakes, mushrooms, bamboo shoots, etc. were not considered to be valuable foods because their nutritional value was low due to their low content of various nutrients and the carbohydrates which they contained were dietary fiber without digestive enzymes. However, as obesity and metabolic syndrome became common and excessive energy intake became a problem, foods with low energy content and weak digestion and absorption were evaluated as valuable foods.

This is also true for individuals. I am often asked, “Is food X good for health?” To such a question, I answer, “It is good for those for whom it is effective.” This is not a joke or an insincere answer, but my true meaning. If the ingredients of a certain food are effective in improving a person’s current state of health and nutrition, it can be said to be said to be a healthy food for that person.

Improving health and nutritional status refers to the intake of energy and nutrients, etc., in order to maintain and improve health and keep people away from nutritional risks and disease. For example, if a person is obese and concerned about blood glucose and triglycerides, it makes sense to choose low-energy, low-fat, and low-sugar foods, but if a person is thin and prone to low blood glucose, these foods are not only meaningless but even unhealthy.

Choosing the right foods that form a healthy diet is not a matter of looking for “health foods” or “immortality foods” that work for everyone, but rather whether or not they are effective in improving one’s health and nutritional status.

2.2 Nutritional Status of Humans

In order to select appropriate foods and supplements, the first step is to determine and assess the nutritional status of the user. Therefore, let us consider “what is nutritional status”.

The components of the human body are constantly decomposed and replaced by newly synthesized ones as they become older. Moreover, some of them are decomposed and some are reused, but they are finally excreted through urine and skin. However, if the amount of nutrient intake is low for some reason, or if the amount of a nutrient required increases due to exercise or disease, and the level of degradation exceeds the level of synthesis, a nutrient deficiency will occur. If the deficiency is significant and prolonged, metabolic homeostasis cannot be maintained, leading to nutritional deficiency and disease. These changes start with biochemical changes in the cells, followed by physiological changes over time, and finally morphological changes in the tissues and organs. Such a comprehensive evaluation of changes in nutritional status is called nutritional assessment.

2.2.1 Nutritional Deficiencies and Excesses

The nutritional status of the human body can be roughly divided into deficiency and excess, with the former divided into deficiency and latent deficiency, and the latter into excess and latent excess.

Nutritional deficiency is a condition in which the deficiency of nutrients is prolonged and physical and mental abnormalities appear, such as beriberi, night blindness, scurvy, and rickets. Various kinds of nutritional supplements are required for treatment. Latent deficiency is a condition in which the body is not deficient in nutrients, but the nutritional intake is insufficient, and the body’s storage of and metabolic capacity for nutrients are reduced, resulting in the appearance of various complaints. Since the body has a natural healing power, the deficiency can be improved by improving the daily diet and nutritional supplements.

Excessive nutrient intake is a state of addiction in which a large amount of a specific food or supplement is consumed, resulting in long-term excessive nutrient intake and the appearance of physical and mental abnormalities. In addition, it can result in non-infectious chronic diseases such as obesity, diabetes mellitus, dyslipidemia, hypertension, hyperuricemia, and arteriosclerosis, or so-called lifestyle-related diseases, due to the involvement of genetic predisposition to the excess nutrients. A potential excess state is a state in which various clinical laboratory values are not abnormal enough to be diagnosed as a disease, but the nutrient intake is excessive, the amount of body fat increases due to obesity, the metabolism of energy and nutrients is altered, and noncommunicable diseases: NCDs are easily induced. Metabolic syndrome is a condition in which the body fat, blood glucose, blood lipid, and blood pressure are above the standard values, but not high enough to be diagnosed as obesity, diabetes, dyslipidemia, or hypertension.

2.3 The Birth of Nutrition

From ancient times to the present, the relationship between diet and health or disease has been discussed many times. Various dietary methods have been proposed as methods to preserve health, maintain a regimen, and even prevent and treat diseases. Many of these traditional diets are based on the laws of human experience and observation of nature. For this reason, there was no concept that as ingested food is digested, certain components are absorbed, and that these components are related to the activities of life. Nutritional science, however, has developed physiology and biochemistry, discovered the components of life and growth in food, and clarified the universal relationship between food and life. I believe that nutrition is the study that has scientifically clarified the relationship between food and the activities of life. Therefore, it can be said that nutrition is the science that forms the basis of life science. Then, who gave birth to the concept of “nutrition”? In other words, who first came up with the idea of “nutrition”? To find the answer to this question, we first need to briefly unravel the history of science.

2.3.1 Nutrition and Life Sciences

At first, it was during the Greek era that human beings began to think deeply about the phenomena of the world. At that time, the so-called intellectuals discussed the philosophical issue of “What is a human being?” They were discussing a philosophical question. However, since human beings have many different aspects, no matter how many times they debated, they ended up arguing for the sake of arguing, and this did not lead to the progress of human beings.

In the early seventeenth century, an era of rapid academic progress arrived in Europe. René Descartes (1596–1650), a Frenchman who grew up in that era, was regarded as the founder of modern, rationalist philosophy. He separated the human body from the mind, making the human body the object of natural science, which pursues objectivity, and the mind the object of psychology, literature and art. He proposed the so-called human machine theory, which can be said to have laid the foundation for life science, which interprets life in terms of material change. In the life sciences, universality was emphasized, and issues of the mind and emotions were eliminated, leading to progress in anatomy, physiology, biochemistry, and molecular biology. Nutrition was developed as a part of these life sciences.

I believe that it was the discovery of combustion and energy metabolism that provided the starting point for nutrition to become an independent academic system within the life sciences. Human beings have long had an unusual interest in the phenomenon of burning. When something burns, it produces light that brightens up the world and heat that warms up our bodies, thus enriching our lives. Moreover, all animals fear fire and keep away from it, and only humans developed civilization by making and using fire.

2.3.2 The Founder of Nutrition

Until around the seventeenth century, it was believed that light and heat were produced by the release of phlogiston, the element that burns when an object burns. Lavoisier, a French scientist in the late eighteenth century, believed that combustion was a phenomenon in which metals reacted with oxygen, and that the respiration of animals and the combustion of things were similar. He proved that living organisms consume oxygen and produce carbon dioxide gas when they breathe, and that the amount of carbon dioxide gas is proportional to the heat produced, and he found that energy metabolism increases with food intake and exertion. It can be said that he is the “founder of nutrition” who opened the door of nutrition by proving that man obtains the energy for life from food. However, some say that he only studied respiration as a part of physiology and did not consider nutrition as an independent science.

2.4 Systematization of Nutritional Science

2.4.1 Calorimetric Studies

In 1866, Carl Feucht of Germany built a large calorimeter to directly measure human energy expenditure, and Max Rubner, a student of his, reported in 1883 that energy metabolism was proportional to body surface area. In 1902, Rubner laid the foundation for calculating the amount of energy consumed by calculating the physiological burning of carbohydrates, fats, and proteins, and he is considered by some to be the “founder of nutrition.” The calorific value of nutrients is 4 kcal for carbohydrates, 9 kcal for fats, and 4 kcal for proteins per gram. This number is called “the Atwater calorie factor” and is considered to be the most important coefficient in nutrition. Even now, the “Atwater Award” is the most prestigious award of the National Society of Nutrition. This coefficient means that licking a mere 1 g of sugar grabbed with three fingers generates 4 kcal of physiological energy in the body. 4 kcal of heat is the amount of energy that can raise the temperature of 4 l of water by 1 °C. It can be understood that the human body produces energy efficiently from nutrients and uses a large amount of energy to maintain life.

2.4.2 Carbohydrate and Fat Research

In the nineteenth century, the digestion of carbohydrates was elucidated and various digestive enzymes were discovered; in the early twentieth century, research on the metabolism of absorbed carbohydrates began, and in 1937, Hans Krebs (Germany) discovered the TCA cycle, in which carbohydrates are glycolyzed and oxidized to carbon dioxide and water to produce energy. The oxidation of lipids to produce energy was explained. Justus Liebig et al. (Germany) discovered that fats are synthesized from other nutrients, and that fats are not only a source of energy but also contain essential fatty acids that are involved in physiological functions such as growth, reproduction and formation of skin.

2.4.3 Protein Research

In the nineteenth century, full-scale research on proteins began, and it was found that the nutritional value of proteins was related to the amount of nitrogen contained in foods. In the twentieth century, it was confirmed that proteins are composed of amino acids, and it was clarified that the quality of proteins is determined by their amino acid composition. Subsequently, research developed into the classification of essential amino acids, which are not synthesized in the body, and non-essential amino acids, which are synthesized in the body, the requirements for amino acids, the balance of amino acids, and the physiological effects of various proteins and amino acids.

2.4.4 Vitamin Research

In the late nineteenth century, it was discovered that nutrients included not only the energy-producing nutrients of carbohydrates, fats, and proteins. There was also speculation about the existence of micronutrients. For example, in Japan, people who had the habit of eating too much white rice suffered from an intractable disease with neurological symptoms, and many soldiers died of this disease during the Sino-Japanese War and the Russo-Japanese War. Later, it was discovered that the disease was caused by a deficiency of vitamin B1, which led to the discovery of the existence of micronutrients. The Army believed that the disease was an infectious disease, and enforced hygiene, but because this did not improve the diet, they were unable to reduce the number of patients, and the number of deaths from the disease was four times that of the actual war dead. The Navy, on the other hand, prevented beriberi from early on by switching from a diet centered on white rice to a Western diet centered on meat, as there were no cases of beriberi in the West.

In 1890, Eijkman (Netherlands) discovered that rice bran could be added to the feed of chickens showing symptoms of beriberi, and in 1911, Funk (Poland) succeeded in crystallizing the active ingredient from rice bran, which had the properties of an amine, and named it the amine of life, or “vitamin”. In Japan, too, Dr. Umetaro Suzuki (鈴木梅太郎) succeeded in crystallizing the active ingredient from rice bran and clarified that beriberi was caused by a vitamin B1 deficiency.

In Europe as well there were great nutritional accidents and discoveries. From the sixteenth and eighteenth centuries, some two million sailors died of a mysterious disease. In 1747, Captain James Cook (England) followed the advice of Dr. James Lind and prevented the disease by feeding his sailors citrus fruits, a local folk remedy at the time. The disease was scurvy, a vitamin C deficiency caused by a lack of fresh fruits and vegetables. In other words, at that time, Asia was suffering from a vitamin B1 deficiency, while Europe was suffering from a vitamin C deficiency.

2.4.5 Mineral Research

In the eighteenth century, iron was found to be contained in blood, and bones were found to be composed of calcium and phosphorus. In the twentieth century, various mineral deficiency diseases were discovered, and the physiological effects of minerals and their content in foods, for example that goiter is caused by iodine deficiency were explained. Since then, many vitamins and minerals have been discovered.

When we look at the history of the development of nutritional science, we can see that first the nutrients that produce energy for life were discovered, and then the nutrients that make up the human body and carry out life activities were discovered, and the framework of the current five major nutrients was established. Finally, the characteristics of the foods containing these nutrients, a rational manner of intake, and the deficiency and excess of nutrients were discovered, and the relationship between food and drink and health and disease could be interpreted scientifically, and the academic systematization of nutrition was prepared.

2.5 Composition and Nutrition of the Human Body

Since nutrition is the scientific study of the relationship between the human body, food, and diet, we will first consider nutrition from the perspective of the human body.

2.5.1 Changes in Nutrients in the Human Body

The human body is composed of cells, tissues, and organs, and life is maintained by these interacting and working smoothly. 16.4% of the human body is protein, 15.3% is fat, 5.7% is mineral, less than 1% is sugar, and the rest is water. On the other hand, carbohydrates, lipids, and proteins constitute 57.7%, 26.3%, and 16.0% of the daily diet, respectively.

In other words, the human body is composed of nutrients as well as food, but the nutritional components of food are not directly utilized by the living body. The absorbed nutrients are mainly converted into suitable new nutrients in the liver, then stored, and finally circulated throughout the body to supply the needs of each organ and tissue. For example, when a person eats steak, which is the muscle of a cow, the protein ingested does not directly become the protein that makes up the muscles of a person. The protein in the steak is digested by digestive enzymes and absorbed in the form of amino acids, which are then combined with amino acids broken down from the proteins that make up the human body and are used to synthesize the protein needed by the person.

The blueprint used for this synthesis is the gene inherited from one’s parents, and the protein suitable for the person is manufactured based on this information. If beef proteins were used as they are, the muscles of people who eat steaks would be the same as those of cows, but this is not the case. In other words, the proteins contained in the food we consume have species-specific characteristics, but if they are broken down to amino acids, the specificity of beef will disappear in the human body.

2.6 Nutrition and Biochemistry

Recent developments in molecular biology have revealed the metabolism and action of nutrients at the cellular and genetic levels. For example, a cell has a cytoplasm and a nucleus, and the cytoplasm includes mitochondria, lysosomes, an endoplasmic reticulum, and a Golgi apparatus. Mitochondria produce ATP, a component of energy, lysosomes produce proteins, the endoplasmic reticulum transports substances, and the Golgi apparatus encases proteins produced by ribosomes and transports them out of the cell. The synthesis, degradation, and metabolism of nutrients are now understood at the cellular level.

2.6.1 Conflict Between Nutrition and Biochemistry

Let us consider the relationship between cells and genes and also nutrition. Traditionally, nutrition and biochemistry were on a friendly honeymoon, and it was the biochemists who led the basic research in nutrition. In 1953, the double helix structure of DNA was elucidated by Watson and Crick, and biochemical research focused on the genome, which is an internal factor of the human body. After the elucidation of the double-helix structure of DNA by Watson and Crick, biochemical research became focused on the genome, and neglected nutrition, which is an external factor. The study of basic nutrition came to be treated as a minor part of biochemical research. At that time, nutritional deficiency caused by the food shortages due to World War II had been solved, signboards for the “Nutrition Laboratory” disappeared from the laboratories of universities in Japan, because the original research goal of nutrition became diluted. Nutrition also disappeared from medical education and training, nutrition researchers began to call themselves biochemists, and nutrition lost its luster.

However, by the end of the twentieth century it became clear that there is a mechanism that determines the function of genes regardless of the DNA base sequence. The sum total of such information is called the epigenome. In other words, it is now known that a person’s individuality and diseases are not determined merely by the content of his or her DNA, but are also related to the mechanism called the epigenome. In the nucleus of a cell, the 46 chromosomes inherited from both parents are stored; the chromosomes consist of a double-helix structure of deoxyribonucleic acid (DNA) linked in chains. When the genetic information incorporated in DNA is read for physiological functions, it is called gene expression. In gene expression, the information in DNA is copied into messenger RNA, and amino acids are combined in the ribosome according to this information to synthesize the necessary proteins. In other words, the genetic information from the parents is transmitted from DNA to mRNA to protein, resulting in a body that resembles the parents, but is unique to the individual.

However, about 60 trillion cells in the whole body contain genes in almost the same way, but each of them develops into a component of a unique organ, and some cells become legs, and some cells become skin. This is because there is a device that turns on and off the action of genes in DNA, and it was found that this is controlled by various chemical modifications (methylation and acetylation) that bind to histone proteins that DNA is wrapped around.

Although the same genome is contained in all the cells that make up the human body, they can become various types of cells. In addition, identical twins have the same genome, but their appearance is similar but not identical, and if they grow up in different environments, they may have different body shapes, develop different diseases, and have different life spans. In other words, this reveals that human individuality and health conditions are determined not only by genetic information in the genome but also by differences in the epigenome. And when overeating, unbalanced nutrient intake, and stress are added, changes and abnormalities occur in this regulatory function, resulting in differences in protein production and function, the emergence of individual conditions, the inability to maintain health, and consequently, disease.

2.6.2 Linkage Between Nutrition and Biochemistry

Nutrition, the study of the external environment of the human body, and biochemistry, the study of the mechanisms within cells, are once again becoming more closely linked. When genes are compared among individuals, their nucleotide sequences may differ, and when these changes occur at a frequency of 1% or more of the population, they are called genetic polymorphisms. It has been found that if inappropriate dietary habits are followed by people with such genetic polymorphisms, they are more likely to develop diseases. Therefore, genetic diagnosis can reveal the constitution of an individual that makes him or her susceptible to developing a disease, which can be more reliably prevented if that person works to improve his or her eating habits from an early stage so that gene expression does not occur. For example, if there is a polymorphism in the gene for diabetes, the secretion function and sensitivity to insulin will be reduced, and the person will be prone to diabetes even if he or she is not overweight. Therefore, it is important to control the condition by losing weight, and if this is done, the onset of diabetes can be prevented more reliably. In other words, it is beginning to be understood that nutrients and diet play a role as the materials that make up the organism, and at the same time, affect the action of genes, which are the blueprint of the organism.

2.7 Advances in Nutrition and the Human Diet

Nutrition has been around for almost 200 years, since Lavoisier opened its doors. During this time, remarkable progress has been made. In medicine, central venous nutrition, which uses a tube to supply nutrients directly into the bloodstream, came into use, saving the lives of patients who had lost the function of their digestive organs, such as those with Crohn’s disease. Humans now have a way to live without food, by administering nutrients directly into the body. Since infusions can contain only those nutrients that are known to man, what this method of nutritional supplementation alone means is that we have discovered almost all the nutrients that are the building blocks of life, meaning that we can live for decades.

If we draw this conclusion, we can live if we take all the necessary nutrients in pill form as a supplement every day. We will be free from troublesome shopping and cooking, and most of all, we will not need agriculture. People will be freed from food crises, starvation and malnutrition. When I first became interested in nutrition, I dreamed of a society in which people could wake up in the morning, throw a few supplements in their mouths, and not have to eat.

2.7.1 Development of Complete Nutritional Foods

In fact, there are people who have made this dream come true. They were the nutritionists who participated in the Apollo missions that landed man on the moon for the first time.

In 1970, three astronauts aboard Apollo 13 returned to Earth within two weeks of arriving on the Moon. What they ate during that time was “space food,” a complete nutritional food that could keep them alive if they ate only that, and did not produce any stools. At the time, the American nutritionists who conducted the research were praised worldwide, and it was reported as a victory for American nutrition. I remember thinking with regret that I had been beaten to the punch.

However, further development of this space food was later frustrated. The reason for this was that the space pilots complained that if they were forced to eat something like toothpaste in cheesecloth at every meal, the food would become stressful and interfere with their work.

Whether human beings have discovered all the nutrients or not is not the issue, but there is a big difference between drinking or consuming all the nutrients from a tube and eating food prepared from nature. In addition to nutritional support, meals have the significance of providing the color, texture, aroma, and taste of the food, and are related to the production, distribution, processing, and cooking of the food, as well as the local culture, economy, and climate that make these processes possible. Since nutrition science is based on modern rationalism and uses elemental reductionism as its methodology, it tends to lead to the final conclusion of “rational, convenient, and inexpensive supplementation of nutrients,” but we must not forget that diet is formed from a wide variety of factors and purposes.

The process of production, distribution, processing, and cooking is becoming more and more rationalized and simplified by the use of AI and robots, not only for space food or nutritional support for the sick and injured, but also for daily meals, and is moving farther and farther away from the “heartfelt meals prepared with time and effort” that humans originally enjoyed. This direction is inevitable in modern civilized society, which is based on modern rationalism, and its original sin may be found in Descartes’ philosophy, which divided human beings into the human body and the mind, and became the foundation of modern science. However, it is precisely because we live in such a society that I believe we must develop “human nutrition,” a field that explores the nature of nutrition and diet in a way that is closer to human beings.

2.8 Human Evolution and Nutrition

2.8.1 The Need for Nutrition Science

I have been able to understand the birth of the concept of nutrition and the development of nutritional science by exploring its history, but why, in the first place, humans need knowledge of nutrition science. Pandas eat only bamboo leaves and koalas eat only eucalyptus leaves, but their muscles are well developed and they live well. Even if we don’t limit ourselves to such herbivores, there are no animals other than humans that eat with any consideration for nutrition. Even so, they grow normally and live their whole lives. Why can’t humans live without thinking about this and that and eating?

I believe that the reason for this lies in humans having the eating habits of an “unbelievable omnivore”. What we call food in our daily lives are animals and plants that exist in the natural world. However, these animals and plants do not originally exist to be used as food for human beings. Each food provides some of the nutrients necessary for human beings, but the composition of the food is for the animals and plants to survive, not for the maintenance of human health.

For example, pork contains a lot of protein and vitamin B1, but it is also a food with a lot of saturated fatty acids, so it is an excellent food for supplying protein and vitamin B1, but eating too much of it can lead to obesity and dyslipidemia. In fact, there is no “complete nutritional food” in the natural world that contains all the nutrients necessary for humans. Humans have never encountered a “so-called health food” like bamboo leaves for pandas, which could keep us alive if we eat only that. Therefore, humans chose to be omnivorous, which means that we combine a variety of incomplete foods and consume the necessary nutrients in a well-balanced manner throughout our diet. Rather than a conscious choice, it is more reasonable to think that only omnivores survived and evolved into humans. In other words, in the process of evolution, human beings encountered severe food shortages many times and had to eat everything, and each time that they increased the variety of foods they ate, they expanded their omnivory and acquired the adaptability to live anywhere on earth.

As human beings developed their culture and civilization and wished to be healthier and live longer, they began to seek wisdom about what to choose from such a wide variety of foods, how much to eat, and how to cook and consume them. It is my understanding that nutritional science is the scientific elucidation of this wisdom.

2.8.2 Acquisition of Omnivorousness

So what led humans to become omnivorous?

I looked into the process of human evolution. The common ancestor of the present great apes existed about 5 million years ago, from which the orangutans and gorillas were separated, and then about 70 million years ago, the chimpanzees and hominids were separated. We are Homo sapiens was the only one that survived. The other hominids became extinct due to diseases, environmental changes, and predation. Why did we alone survive? There are many theories.

It has long been theorized that the human race evolved from hanging from trees to moving from the jungles of Africa out onto the grasslands, evolving bipedalism, developing large brains, and expanding their diet. However, several species with large brains appeared among the extinct hominids. For example, Homo sapiens’ biggest rival, the extinct Neanderthal man, had a brain capacity of about 1550 cc, while Homo sapiens had a smaller brain capacity of about 1450 cc. Incidentally, the brain of modern humans is even smaller at about 1350 cc. Moreover, the brain consumes as much energy as muscle, and a large brain requires more energy and increases the basal metabolic rate. There is a study that calculated the basal metabolic rate, and according to the study, the basal metabolic rate of Neanderthal man was 1, 2 times higher than that of Homo sapiens. Neanderthals, who were large and robust, needed a lot of energy and food to survive, and were not suited to an environment where food was scarce.

2.8.3 Characteristics and Evolution of Homo sapiens

Homo sapiens was not physically strong compared to other human species; rather, it was stocky and lacked arm strength. However, Homo sapiens formed a monogamous family early on, and males distributed food to females and children. As a result, it became necessary for them to harvest and carry food not only for themselves but also for their families, and they evolved to walk on two legs in a straight line and use their hands to carry large amounts of food. Molecular paleontologist Isao Sarashina refers to this as the “food transport hypothesis”. Because upright bipedal walking was a rational way of moving with little physical strain, humans were able to obtain food from distant places and increase its variety. They actively left the jungle and began to eat leftovers from carnivores. These animal foods were easy to digest and rich in high quality proteins, fats, vitamins and minerals, which made it easier for humans to digest and develop their brain functions as well as their brain size. Herbivores eat cellulose from plants, and microorganisms in the digestive tract produce various active ingredients through fermentation, which they absorb and use as nutrients, but with this method, they have to eat a large amount of plants and constantly chew, swallow, and digest.

By developing brain functions, Homo sapiens used fire, advanced hunting techniques, and agriculture, evolving to be increasingly omnivorous and expanding their living area to every corner of the earth. For example, our greatest rivals, the Neanderthals who evolved in Europe, were robust, smart, and active, but they ate only a limited range of foods. In human terms, they were “picky eaters”. As the Earth entered a cold period and the flora and fauna dwindled from the land masses of Europe, the Neanderthals lost their food supply and became extinct, with the Gibraltar Peninsula being the last place they lived. On the other hand, Homo sapiens, which evolved in Africa, survived by expanding its omnivorous diet to include fish, shellfish, and seaweed when food became scarce on land during the cold season.

In the process of evolving the function of upright bipedal walking, humans expanded their omnivorous nature and urvived the harsh changes in the global environment. It would be better to say that humans did not choose to be omnivorous, but that only omnivores survived. However, this omnivory has left us with an important problem. This is the need to make proper food choices from a wide variety of foods, and nutrition was the answer to this problem. In world history, there have been several cases of groups of people who, for some reason, lacked certain foods or ate too much of certain foods, and when they could not maintain a proper omnivorous diet, their health was damaged, they died in large numbers, and they became almost extinct.

“What is a proper omnivore diet?”

To put it simply, it is “a diet in which all nutrients are consumed without excess or deficiency.” Specifically, it is a diet in which carbohydrates are consumed from grains such as rice, bread, and noodles; proteins and fats are consumed from meat, seafood, eggs, and soy products; and vitamins and minerals are consumed from milk and dairy products, as well as from vegetables and fruits.

As mentioned above, our ancestor, Homo sapiens, evolved into modern humans by choosing to be omnivorous, eating all kinds of plants and animals in order to survive in a harsh environment. The industrial revolution, which took place in Europe in the eighteenth century, enabled a cultured and affluent diet and created a society in which the population grew remarkably and people could live longer. This was supported by the “science of nutrition” that was born in that era.

At present, “nutrition” has become a subject of systematic research and education and has created an independent academic system of “sciences of nutrition”. It consists of “basic nutrition” that deals with the basic matters of nutrition, “applied nutrition” that applies and practices nutrition in each stage of life, “food nutrition” that focuses on food, “clinical nutrition” that focuses on the individual human being, and nutrition for public health that focuses on groups or society. In addition, there are “nutrition education theory” and “food service management theory” as methodologies to put this knowledge into practice.