Proteins: all about these essential macro nutrients
Protein is a macro nutrient and plays several essential roles. For iron health and energy boost, here is how to adapt your diet with proteins, according to your age. Decryption in this article.
Proteins, what are they?
Proteins are the main structural components of all cells in the human body.
Proteins are chains of amino acids that can enter into the composition:
- muscles ;
- skin ;
- nails ;
- hairs ;
- some blood.
Proteins are also the basis of many hormones, enzymes and antibodies and are necessary for the growth, repair and defense of tissues in the human body.
Characteristics of proteins
Proteins have many characteristics, they are:
- macronutrients essential for life;
- made up of amino acids, essential or not, which define the quality of the protein;
- in food, there are animal proteins and vegetable proteins;
- have many roles in the body (enzyme, transport, tissue structure, etc.);
Indeed, protein needs change over the course of our lives.
Why eat protein-rich foods?
Protein provides energy, or 4 calories per gram. Like lipids and carbohydrates, proteins are essential macronutrients for the body.
C-reactive protein, a marker of inflammation
C-reactive protein (or CRP) is a protein synthesized by the liver during inflammation.
The CRP assay is very common during a blood test, it allows you to see if the body is facing an attack.
Sources of essential amino acids
There are more than 20 natural amino acids found in dietary proteins.
Nine are important amino acids that the body cannot manufacture. They must therefore be obtained through food.
The other amino acids are non-essential because the body can produce them.
Proteins participate in cell renewal, particularly in muscle tissue, skin and bone tissue.
Proteins play many different roles in metabolism.
Some proteins are digestive enzymes allowing the assimilation of food molecules, others form antibodies and allow the body to defend itself against external aggressions.
Finally, proteins also enter into the composition of hemoglobin and certain hormones.
20 High Protein Foods
The main sources of protein are products of animal origin (meat, fish, eggs and dairy products).
Certain foods such as legumes, nuts and seeds, and grain products are excellent sources of plant-based protein.
Finally, some protein-rich vegetables also help cover the body’s needs.
|Chicken breast, cooked, skinless||100g||31g|
|Ground beef, lean, cooked||100g||30g|
|Pork, chop, cooked||100g||29g|
|Game meat, horse, cooked||100g||28g|
|White fish (cod, sole, cod)||100g||23-26g|
|Oily fish (salmon, trout, mackerel, etc.)||100g||23-25g|
|Firm cheddar-type cheese||50g||11-12g|
|Sliced ham/turkey breast||2 slices (50g)||9g|
|Milk 0, 1, 2 % mg||1 cup (250ml)||9g|
|Fortified soy beverage, all flavors||1 cup (250ml)||6-8g|
|large eggs||1 (50g)||7g|
|Natural Peanut/Almond Butter||2 tbsp. soup||5-7g|
|Whole wheat bread||1 slice/30g||4-6g|
|Yogurt 0 to 2% mg||100g||4g|
How to use protein well?
Use of proteins
|Population||ANC = Recommended Dietary Intake (in g/kg/day)|
|Babies 0-6 months||1.52*|
|Babies 7-12 months||1.2|
|Babies 1-3 years old||1.05|
|Children 4-8 years old||0.95|
|Boys 9-13 years old||0.95|
|Girls 9-13 years old||0.95|
|Boys 14-18 years old||0.85|
|Girls 14-18 years old||0.85|
|Men 19-50 years old||0.80|
|Women 19-50 years old||0.80|
|Men 50 and over||0.80|
|Women 50 and over||0.80|
*Insufficient data to calculate an ANC, therefore an adequate intake (AI) was determined.
There is not enough scientific data to support a higher ANC in physically active people.
On the other hand, since the type of exercise, its intensity, its duration and its frequency affect the use of proteins by the body, a protein intake above the ANC is often recommended for very active athletes (intense training every day ).
Here are the recommended amounts:
- Endurance athletes: 1.2 to 1.4 g/kg/day;
- Strength athletes: 1.2 to 1.7 g/kg/day;
Healthy adults can safely consume up to 25% of their total calories as protein.
In France, individuals consume on average about 17% of their calories in the form of protein.
Animal proteins (meat, dairy products, eggs) are complete proteins, that is, they contain all the amino acids essential for growth and maintaining the integrity of the body.
Vegetable proteins, on the other hand, do not contain all the amino acids in sufficient quantity to make them complete proteins. However, soy is an exception to this rule and contains all the essential amino acids.
In order to supplement vegetable proteins, there are several options:
- Combining a vegetable protein with an animal protein (for example, chili con carne);
- combine legumes (beans, lentils, chickpeas) with cereal products (for example, a couscous and chickpea salad);
- combine legumes and oilseeds (for example, a salad of lentils and almonds).
It was long believed that it was necessary to make these associations within the same meal to ensure complementarity.
Recently, it has been shown that if complementary foods are consumed within a 24 hour period, the benefits of complete protein are present.
However, pregnant women must make these food combinations within the same meal.
There are many protein diets and their indications are multiple.
Increasing the protein intake can be particularly recommended to fight against undernutrition or against malabsorption phenomena.
Similarly, for athletes, it may be recommended to consume protein around bodybuilding sessions to promote the development of muscle mass.
This supplementation can be done naturally through food or with the help of protein powders and other specialized supplements.
There are also protein diets for weight loss. However, they have never yet proven their worth in the long term.
Whatever your situation and before increasing your protein intake, it is recommended to consult a nutrition professional. Indeed, this is not without consequences.
Adverse Effects of Proteins
Consequences of a protein deficiency
An adequate amount of protein each day must be present in order to prevent protein-energy malnutrition.
Protein deficiency is very rare in industrialized countries, but can occur in hospitals in people with a disease as well as in the elderly.
On the other hand, in developing countries, marasmus like kwashiorkor, two forms of protein-energy malnutrition are very present and cause the death of approximately 6 million children each year.
A protein deficiency has negative impacts on all organs and body systems such as the brain, cerebral function, immune system and kidney function.
Signs related to protein deficiency are edema (fluid retention or swelling), reduced muscle mass, dull skin and fine, brittle hair.
The risk of having excessive protein intake from food is slim.
However, some scientific studies carried out with high protein diets have shown an increase in gastrointestinal disorders or a higher risk of osteoporosis or kidney stones.
On the other hand, the most recent data suggest that protein intake is not linked to the loss of calcium from the bones or to other negative effects on bone health.
Some high protein diets are often very high in animal protein and therefore high in saturated fat as well. It is therefore not surprising to see in the literature the correlation between the consumption of red meat and high-fat dairy products and cardiovascular diseases as well as certain types of cancer.
People with chronic kidney disease and certain genetic disorders should continually assess their protein intake and should work with a dietitian to achieve this.
Protein interactions with other nutrients
Interactions between proteins and other nutrients are extremely numerous.
For example, they are responsible for transporting the smallest nutrients into and out of the body’s cells. In this sense, it can be said that an optimal nutritional state is essential for the proper functioning of the whole organism.
Chemical Properties of Proteins
Proteins are the basic macro nutrients of all living organisms. Amino acids linked together by peptide bonds form polypeptide chains. These polypeptide chains arranged together form, in turn, proteins.
The protein chains are synthesized inside the cell itself, in the ribosomes. The sequence of amino acids, called sequence, will determine their structure and function. All amino acids (except proline) consist of a carboxylic acid, a primary amine and a side chain.
There are 22 protein ogenic amino acids, 9 of which are called essential, which the body cannot synthesize.
Protein electrophoresis is a method of protein analysis mainly used in medicine for the study of blood plasma. It allows to analyze from a simple blood test, the level of different proteins contained in the body.
Thus, it is possible to measure albumin, the rate of which indicates malnutrition or certain pathologies of the liver or kidney.
Proteins were discovered in 1835 in the Netherlands by chemist GJ Mulder.
The name protein comes from the Greek word “protos” which means first, in the essential sense.
Since then and over the centuries, the multiple roles of proteins in the human body have not ceased to be highlighted by scientists.