Proteins- their role in nutrition, recommended daily intakes and best sources


Article written in collaboration with Alina Tomoiaga, Nutritionist Technician.

We continue to approach the topic of macronutrients. This time we are looking into proteins along with the daily recommended doses for consumption as well as the best sources. 

We reiterate the fact that a healthy diet is the result of a variety of foods that must include all essential nutrients.

Proteins belong to the category of macronutrients essential for survival and are made up of chains of amino acids. Amino acids have structural, energetic and functional roles. 

Proteins are made up of carbon, nitrogen, oxygen, hydrogen, and they sometimes contain metals (iron, manganese, zinc, etc.). One of the essential components is nitrogen, so a popular name for proteins is that of “nitrogenous substances”.

We return to amino acids, which are the basis of the structure of proteins and which have a metabolic role in the body. They fall into several categories, as follows:

I. Non-essential amino acids – which are produced by the body, so it is not necessary to supplement them from other sources, unless external elements such as stress prevent their natural production. This category includes:
Alania- helps assimilate vitamin B6 and is a source of energy for the nervous system
Asparagine- helps the development of the brain
Aspartic acid- helps with the production and release of hormones and supports the proper function of the nervous system
Glutamic acid- helps the nervous cells of the brain to send and receive information from the cells in the body

II.Conditionally non-essential amino acids – which are not produced by the body, so it is sometimes necessary to supplement them from other sources. This category includes:
Glutamine – maintains intestinal health and supports muscle mass growth
Glycine – component of creatine, ensures bone health and optimal brain function
Proline – supports the formation of collagen and helps in the healing process of wounds and skin lesions
Serine- contributes to memory improvement and sleep quality
Tyrosine- essential for the production of substances such as dopamine, epinephrine, norepinephrine
Ornithine- supports the rapid healing of injuries
Arginine- helps in treating heart conditions and erectile dysfunction
Cysteine ​​- contributes to the formation of collagen and has antioxidant properties

III.Essentail amino acids– are the substances obtained strictly through nutritions and their role is to support muscular development by synthesizing proteins. This category includes:
Lysine – supports the growth of muscle mass
Histidine- facilitates growth, creation of blood cells and tissue regeneration
Threonine- helps to metabolize fats
Methionine – helps to eliminate heavy metals from the body
Valine- essential for emotional calm
Isoleucine- plays a role in the production of growth hormones, helps regulate blood glucose levels
Leucine- plays a role in the production of growth hormones, helps regulate blood glucose levels
Phenylalanine – supports brain functions
Tryptophan – necessary for the harmonious development of children

The elements presented above are amino acids, the foundation of proteins, and we must make sure to get the proper doses intake on a daily basis. Some important sources of amino acids are:
-quinoa- contains all essential amino acids
-mushrooms- contain 17 amino acids that include all essential ones
-legumes- beans, soy, chickpeas, lentils and peas are among the best sources
-nuts and seeds- almonds, pumpkin, hemp, chia

The impact of proteins in the organism is an extension of the roles played by fats and carbohydrates: 
-They are components of tissues, enter the structure of all cells and are part of the process of cell growth and recovery
-They enter the structure of some hormones whose role is important in regulating body functions
-They take part in the distribution of water and solutes in the body
-They protect the body against microbes and toxins, contributing to the formation of antibodies
-In certain situations, proteins can be metabolized in the body with an energetic role.

The big group of proteins is divided as well into:

Complete proteins, most of which come from animal foods. They contain all the essential amino acids.

Partially complete proteins are present in some legumes and grains, nuts, seeds, vegetables and fruits. They have essential amino acids in their structure, but not in optimal proportions to ensure protein synthesis in the body. They have the ability to maintain the body’s protein balance, but in order to maintain growth, a higher and more diverse intake is required compared to complete proteins.

Incomplete proteins, as their name suggests, are proteins whose structure lacks one or more essential amino acids, and the existing ones are present in unbalanced proportions. They are present in corn husks, skin, cartilage and joints.

It should be noted that excess animal protein is not beneficial to the human body, so any protein surplus that is not metabolized by the body goes into putrefaction and is later eliminated through the excretory system.

It should be mentioned that the proteins recommended for consumption on a global scale are those of animal origin, but if we talk about their quality and the process of metabolization through a correct association, those of plant origin are more effective for our bodies. 

This aspect is directly related to the acidification process of the body, namely, too much animal protein is strongly acidifying, when in fact the human diet must be predominantly alkaline.

The daily protein requirement varies according to age and the efforts to which the body is subjected:

Infants aged 0-1 years
2-3 grams/ each body kilogram in the case of natural nutrition
3-4 grams/ each body kilogram in the case of artificial nutrition

Children aged 1-3 years
14-15% of the daily calorie intake

Children aged 3-6 years
13-14% of the daily calorie intake

Children aged 7-12 years and teenagers
13% of the daily calorie intake

1,2-1,5 grams/ each body kilogram (11-13% of the daily calorie intake)

1 gram/ each body kilogram (10% of the daily calorie intake)

Pregnant women need an extra 20 grams of protein and an additional 40 grams of protein during the lactation period.

Athletes need 2-2,5 grams of protein/ each body kilogram in order to cope with the additional effort the body is subjected to. 

With this article we conclude the topic of macronutrients. It is imperative to provide the organism with a balanced intake of fats, carbohydrates and proteins in order to properly support the body’s functions. A long-term imbalance can lead to a number of complications on our health. And here we are also referring to the miracle diets so widespread on the internet that recommend completely giving up one class of macronutrients. Although there are reserves in the body that can ensure the caloric needs for a certain period of time, depriving the body of these substances is not recommended.

Among the first signals that the body sends in case of a deficiency or, on the contrary, an overdose, are lethargic states, chronic fatigue, depression. Although these states are felt in a subtle way, it is important to react as soon as we notice these differences. But more important is how we act. Not by looking up symptoms online, but by doing a detailed set of medical tests.


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