The human body is an extraordinary machine, in continuous evolution. Some of the protagonists of this process are the amino acids. Known and used for a long time in the field of research and clinical practice; essential amino acids are the key to health. Let’s meet them.

EAAs: what are

In nature there are over 500 amino acids, of which man is able to use only 20 for protein synthesis. Of these, 9 are defined as unconditionally essential: Leucine, Isoleucine, Valine, Lysine, Threonine, Methionine, Phenylalanine, Tryptophan and finally, Histidine, considered as such in recent times only. They must necessarily be introduced with food, because their lack is incompatible with life and the body is not able to produce them autonomously. To be precise, each of the essential amino acids actually has metabolic pathways that can lead to their synthesis, although these are strongly undersized and do not occur in all cell types. In addition, at certain stages of development, the organism also has increased requests for arginine, cysteine, and tyrosine, which in the face of the body’s inability to respond adequately to these needs, are defined as semi-essential.

Essentiality in itself should be understood as a transient concept, defined when in a given organism, a specific nutrient cannot be synthesized in total or sufficient quantity for what are its real needs. Some pathological states, for example, could make essential an amino acid generally not considered as such.

Essential amino acids are essential for protein synthesis


The functions performed in the organism are practically infinite and it is not enough to describe them in depth an article. Essential amino acids are essential for protein synthesis. The lack of only one of them blocks the whole process, even if other amino acids, essential and not, are in abundance. If we think about it, enzymes, immunoglobulins, many hormones are of a protein nature. Without Eaas they could not be produced, missing all their physiological implications. It all starts from here.


The requirement, defined by the OMS, as a quantity to be taken daily calculated as mg per kg of body weight (mg/kg/day) varies from subject to subject and is influenced by countless factors (sex, age, physiological or pathological state, lifestyle). Some situations, such as the early stages of development, pregnancy, seniority or particularly intense sports activities, are characterized by a continuous protein turnover, so the nitrogen demand is particularly high and must be somehow satisfied.

The guidelines provide a general idea about each amino acid:
• histidine: 10-14 mg per kg body weight
• isoleucine: 19-20 mg per kg body weight
• Leucine: 39-42 mg per kg body weight
• Lysine: 30-38 mg per kg body weight
• Methionine: 15-19 mg per kg body weight
• Phenylalanine:25-33 mg per kg body weight
• Threonine: 15-20 mg per kg body weight
• Tryptophan: 4-5 mg per kg body weight
• Valine: 24-26 mg per kg body weight

A varied and balanced diet is ideally able to provide all the nutrients so that the body is not in situations of deficiency. We have always been accustomed to consider food of animal origin as sources par excellence from which to obtain essential amino acids, by virtue of their higher biological value than the vegetable counterpart, possessing a more complete amino acid spectrum, although the usefulness of combining different plant foods to compensate for the deficiencies of each source has now been demonstrated.

A recent current of thought has however introduced an interesting parameter to take into account: the Eaas/Neaas ratio. Studies show that a prevalence of Neeas in diet is a condition detrimental to the state of health; conversely, an imbalance towards Eaas has positive implications also in view of anti-aging. 75% of the body’s needs are covered by 5 amino acids (Leucine, Isoleucine, Valine, Threonine and Lysine), contained in food in percentages of less than 20%, a very small amount.

It is impossible to have foods with an advantageous relationship between essential and non-essential, and our diet consequently leads us to introduce high quantities of the latter. What does this mean? An organic overload for the disposal of nitrogen waste. Here then is that the use of pure and adequately constructed formulas of essential amino acids could be useful in restoring the correct balance.

Energy economy, speed, bioavailability: the triad of strength of free form amino acids

We quickly review the fate of a food protein. Being large molecules, they cannot be absorbed as such (with the exception of some particular cases), so they must undergo a series of processes that reduce them to their elementary components, the amino acids precisely. The digestion process begins in the stomach by the combined action of hydrochloric acid and some proteases (of which there are various categories and classes) with the obtaining of oligopeptids. Subsequently, the action of the pancreatic and intestinal proteases, completes the work allowing the obtaining of free amino acids of/tri-peptides.

These are absorbed by the enterocytes through specific conveyors, they reach the liver through the bloodstream, which will provide their distribution for the most disparate uses. A small percentage of protein does not undergo digestion, and participates in the production of faecal mass that will be eliminated.

The digestive process has a variable duration, influenced by many factors: we can mention the type of food, the cooking method, the presence or not of other macronutrients and/ or dietary fibers, not optimal physiological situations. The result? From the ingestion to the complete digestion of the alimentary bolus it passes a lot of time and the nutritive elements are therefore not readily available for the utilization.

The intake of free amino acids, in specific contexts, is a very intelligent and strategic choice. As they do not have to undergo the action of any proteases, in fact, they are directly absorbed by enterocytes and are poured into the blood very quickly becoming bioavailable, an aspect confirmed by the sudden rise of the amino acid after ingestion.

Mixtures of Eaas: from the clinic to food integration

At the beginning, Eaas mixtures were designed exclusively for medical purposes, presenting a qualitative-quantitative relationship based on the pathologies that were intended to be treated. Think that the first Bcaas were used in the 70s for cases of liver complications, while nowadays they are one of the milestones of food integration.

The binomial miscele-Eaas obligatorily leads to quote Doctor Francesco Saverio Dioguardi. Italian excellence and international authority in the study of metabolism and nutritional therapies, has designed and formulated a patented mixture with stoichiometric relationships "tailored to human needs", defined CATOHN® (Cluster of Aminoacids Tailored On Human Needs) whose main characteristic is to limit the limiting amino acid. The ideal blend, in short, able to respond in a balanced way to energy needs and at the same time to those of protein synthesis.

Amino acid products have increased considerably, given the marketing of numerous formulations, some of which are quite valid and also patented. In addition to the relationship between the various Eaas (for example, the relationship of which could be discussed at length), in evaluating the quality of a supplement it is necessary to analyze the raw material, production methods (plant bacterial fermentation, enzymatic hydrolysis, extraction from organic matrices) and purification and any innovative technologies used.


In which contexts to use a good supplement of essential amino acids?

  • Clinical: in the nutritional approach in the oncological patient, for metabolic pathologies or neurodegenerative disorders
  • Inadequate or incomplete protein intake
  • Specific diet: for example in a high-calorie diet, to give respite to the body from the continuous ingestion of food, or during a low-calorie diet to preserve muscle tissue
  • Sarcopenia: as the age progresses, sarcopenia is one of the main problems regarding the management of an elderly subject.In general, the causes are to be found in the concomitant reduction of physical activity combined with malnutrition calorie-protein induced by criticality affecting the processes of food intake and digestion. In the elderly, therefore, the use of Eaas is strongly recommended (after assessment of the physical/ pathological picture!) to limit the loss of muscle mass and further impairment of health
  • Sport/athlete: because the use of Eaas is optimal for several reasons:
    • They stimulate and increase the rate of muscle protein synthesis (MPS), regenerating the actino-myosine fibers subjected to stress induced by contraction, thus exercising trophic function.
  • They act as energy substrates in case of need, preserving muscle structures from catabolic processes.For this particular function are mainly involved the three branched amino acids.
  • If taken during the peri-workout phase, in combination with fast-assimilating carbohydrates, ensure a constant flow of nutrients to the muscle, bioavailable and ready to be used immediately
  • Facilitate adaptation to the training stimulus
  • Improve and reduce fatigueo Promote the recovery


Personally, I consider the essential amino acid to be a phenomenal element, of which all the involvement and the additional benefits that they bring to health have not yet been outlined. Certainly in the coming years the supporting evidence will become more and more numerous.

A product is worth saying, really for everyone, that it is worth considering to improve one’s health to 360 degrees.


Francesco S. Dioguardi, Gli aminoacidi: lettere di un alfabeto più antico della vita, Sintesi InfoMedica, 2018

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