Understanding metabolism for healthy nutrition

Article by Alessandro Saibene Medico Chirurgo, Responsabile Area Nutrizione Clinica, IRCCS Ospedale San Raffaele di Milano

Nutrition and life mechanisms

Metabolism studies have revealed the mechanisms that allow cells and organisms to survive, grow and proliferate. Today they can be used to increase longevity and improve health. Even through what we eatOur body grows, lives and reproduces through an infinite series of biochemical reactions perfectly harmonic and functional to our species’ survival. In the course of time, these chemical processes deteriorate with a speed that depends on a series of endogenous and exogenous attacks: if recognized and rebalanced, the organism is able to self-regenerate; if neglected, their side-effects add up and over time they become chronic pathologies causing the end of the individual himself.A portion of this complex pattern of chemical reactions is called Metabolism, that is the set of biochemical processes that governs our body energy system and the production of its fundamental building blocks: proteins, nucleic acids (DNA and RNA), fats and other cellular components.A poorly functioning metabolism has an infinite number of negative impacts on our body and its systems, because it affects both the energy level to make them work as well as their structural components.The production of energy occurs through the transformation of substances ingested with food, which also provides an important contribution to the construction of our cells building blocks, thanks to all those nutrients that our body is not able to self-produce.

Al di là del piacere culinario, l’alimentazione ha un ruolo fondamentale nella sopravvivenza e nello sviluppo del nostro corpo, fornendogli componenti essenziali. 

Catabolism and Anabolism

Cell Metabolism is a combination of two processes that alternate: Catabolism and Anabolism. The first is related to the transformation of nutrients into energy, which is measured in ATP units (cellular gasoline); from the latter it depends the trasformation of macro-nutrients into essential cell building blocks and the functioning of our physiological systems.During the catabolic phase, with the help of the oxygen we breathe, our body breaks down food into macronutrients (Lipids, Carbohydrates and Proteins) and releases energy (ATP), thanks to the action of Enzymes, a special group of proteins that accelerate the transformation of macronutrients, activated by our hormonal system (ie. insulin).During the anabolic phase, our body recombines these macronutrients into semi-finished products (amino acids, simple sugars, fatty acids, glycerol) which are then utilized to create larger and more complex structures (macro-molecules) that are essential to the activity of cell proliferation and differentiation and to the functioning of the various systems of our body, leveraging the energy produced during catabolism to make this production process happen. Our hormonal system plays a key role during this phase, in particular the insulin hormone.Catabolism vs Anabolism

the macro-molecules are Proteins, Nucleic Acids (RNA and DNA), Phospholipids and Carbohydrates. All essential components for the functioning and growth of our organism.  

The metabolic pathways, one of the inner secrets of our existence

The anabolic phase is divided into 3 cross-interacting micro-processing laboratories devoted to produce all the essential metabolic building blocks.These are commonly called “metabolic pathways”:
  1. The insulin pathway (GH, IGF-1) reacts to complex sugars ingested and convert them into simple sugars and proteins. Its final mission is the “growth of the organism”, promoting cell proliferation and differentiation, through the supply of energy deposits and structural components.
  2. The mTOR (mammalian target of rapamycin) reacts to the proteins ingested with food and reuses them to build new ones useful for the “growth of the organism”, promoting cell proliferation. This pathway is also responsible for the elimination of old and defective cells (Cellular autophagy) with the double advantage of recycling their building blocks to produce new cells and eliminating them to prevent linked degenerative and inflammatory processes.
  3. AMPK (AMP-activated protein kinase) reacts to the energy level of the body in an inversely proportional way. Since energy is essential to produce macro-molecules for body functioning and its development, this pathway signals if there is enough of it in the body and, if not, it stops the activity of macro-molecules creation by pausing the production activity. The AMPK pathway is a “metabolic regulator”.
All these 3 pathways play a fundamental role in governing our body health and longevity. But before we understand how and why, we must learn a fundamental living principle.

The trade-off between body growth and lifespan

The life balance is dominated by the “principle of survival” of the species, that favors all those processes and adaptations of the organism able to guarantee the best outcomes for its survival in a certain environment and under certain conditions.Every living organism therefore has a survival mechanism that, on the one hand, accelerates its growth and proliferation when environmental conditions are favorable; when not, it can interrupt these processes, pausing them, so as to reduce the need to the minimum and wait for better times.riproduzione cellulare

Our life processes are focused on ensuring the species survival, and not the individual across the time. Understanding their mechanisms is the key to living long and healthy lives. 

Translated in the field of longevity, our metabolism aims to maximize the development of the organism and ensure its reproduction in the shortest time and not to ensure its long term lifespan. This is the reason why some virtuous metabolic processes, over time, become the cause of degenerative diseases, once their function of growth and procreation is exhausted.Therefore, to achieve a long and healthy life even in old age, it is necessary to govern the metabolism in order to slow down the metabolic “cell-growth” processes (as in unfavorable environmental conditions) . Obviously this strategy will have to be absolutely opposite for younger people, let’s say under 40 years of age.In the next article we will discover how to act on metabolic pathways to promote a long and healthy life and how to build a nutrition habit useful for this purpose.

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