History and Evolution of Nutritional Science
Historical Foundations and the Pre-Scientific Era
The field of nutrition has transitioned through a significant evolution over the past years of its existence. In its earliest stages, nutrition was not characterized as a formal science, primarily because it lacked the foundational integration of chemistry required to explain biological processes. Historically, the initial relationship between food and human health was established by Hippocrates, who is recognized as the Father of Medicine. He was among the first to explicitly relate the quality and type of alimentation to the overall health status of an individual. A pivotal moment in the formalization of nutritional thought occurred in Italy with the publication of the first book related to the subject, titled "Regimen Sanitatis de Salerno." This text represents the very first attempt to document a scientific study of nutrition. Further advancements were made by Santorio Santorio, referred to in historical notes as Santorio and Salterio, who authored "Altarismo de Medicina estatica." Santorio was a pioneer in studying metabolism through a quantitative lens. He utilized a scale, often weighing himself while seated, to meticulously measure the inputs and outputs of his body, effectively tracking what entered and what exited his system to understand the physical changes associated with living.
The Eighteenth Century and the Mechanics of Metabolism
During the century, nutritional science experienced major advancements characterized by the introduction of precise measurement tools and the study of chemical processes. A key collaborator in this era was Seguin, who worked alongside Antoine Lavoisier. These researchers pioneered the use of the Roman scale to conduct their experiments. Lavoisier is credited with establishing the critical relationship between respiration and combustion. He determined that respiration is effectively a form of combustion, identifying Carbon and Hydrogen as central components of this process. Lavoisier is known as the primary figure to speak on combustion in a biological context. Seguin contributed by studying the consumption of oxygen during these processes. Their collective work concluded that oxygen consumption in humans increases significantly during physical muscular work and continues to remain elevated following the ingestion of food, linking the metabolic rate directly to activity and digestion.
The Nineteenth Century and the Energetic Concept of Nutrition
The century brought further sophistication to the understanding of nutrients and energy. Justus von Liebig, often referred to as Lievig, became a transformative figure through his publication of the book titled "La química orgánica en sus aplicaciones a la fisiología y patología." In this work, he introduced the concept of "principes inmediatos," which we now identify as macronutrients. Liebig identified Glucose as the principal source of energy for the human body, describing it as our fundamental fuel. Following this, Voit demonstrated that during periods of fasting, the body begins to oxidize its own stored fats and proteins. Voit verified the process of the conservation of energy within biological systems, which established the foundational "Concepto Energético de la Nutrición" (Energetic Concept of Nutrition). Further research was conducted by Atwater, who investigated the human Caloric-Fuel Needs (C.F.N.) under conditions of both rest and physical work. Atwater’s investigations were built upon earlier physiological experiments performed on dogs by researchers Voit and Rubner.
The Scientific Study of Proteins and Amino Acids
The formal identification of proteins as a distinct category of nutrients occurred in when Jöns Jacob Berzelius, noted as Berkelius, coined the term "proteina." He derived this from a concept meaning "primary" or "fundamental," describing it as the very substance of living matter. Jean-Baptiste Boussingault, or Boussin Gault, contributed to this field by studying nitrogen, concluding that protein is the only macronutrient that contains the element . This finding established proteins as an essential and unique component of the diet. Later, Emil Fischer focused his research on identifying the specific building blocks of proteins known as amino acids. Further advancements in identifying these components were made by Osborne and Mendel, who documented the existence of the essential amino acids that the human body cannot synthesize on its own. Henrique also played a role by demonstrating the process of acid hydrolysis of proteins, an achievement that allowed for the isolation of the first amino acids from complex protein structures.
The Discovery of Vitamins and Accessory Factors
The understanding of micronutrients emerged through the discovery of vitamins, a term and concept pioneered by Frederick Gowland Hopkins and Christiaan Eijkman. They established that vitamins are substances necessary for the proper functioning of the body despite being required in small amounts. In , Elmer McCollum referred to these substances as "accessory factors." The medical implications of vitamin deficiencies were soon realized; for instance, the lack of specific nutrients was linked to specific diseases, such as rickets, known as Raquitismo. In , Mellanby described how a lack of Vitamin D specifically affects bone health. He determined that without sufficient Vitamin D, the synthesis of bone tissue is significantly altered, leading to skeletal problems. This era established the principle that a deficit in specific nutrients directly leads to pathological states, highlighting the essential nature of these molecules.
The Interaction Between Diet, Health, and Chronic Disease
The study of nutrition eventually concluded that diet is a primary determinant of health and disease. Desquilibrated or imbalanced diets are direct causes of various illnesses, as both the excess and the deficit of specific nutrients negatively affect human health. Saturated fats are identified as a major risk factor, as high intake is correlated with high cholesterol levels. Chronic diseases are frequently the result of poor long-term dietary habits, often categorized by an excess of energy and fats coupled with a lack of essential nutrients. Furthermore, nutrition plays a role in the development of cancer. This risk can be influenced by specific nutritional deficiencies or by the presence of harmful substances and damage-inducing agents within food products. Thus, the modern view of nutrition encompasses not just the prevention of deficiency diseases but the management of long-term risks through balanced nutrient intake.