Proteins are the main building blocks of all cells in the human body. These are chains of amino acids that can be used to composition muscles, skin, nails, hair, blood, etc. These 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:
- Macronutrients essential for life
- Made up of amino acids, necessary or not, which define the quality of the protein
- In the diet, we find animal proteins and vegetable proteins
- They have many roles in the body (enzyme, transport, tissue structure, etc.)
- Protein requirements change throughout life
Proteins: definition and benefits
Energy role
Protein provides energy or four 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 over 20 naturally occurring amino acids found in dietary protein. Nine are essential amino acids that the body cannot make. They must therefore be obtained through food. The other amino acids are nonessential because the body can make them.
Structural role
Proteins participate in cell renewal, particularly in muscle tissue, skin, and bone tissue.
Physiological processes
They play a lot of different roles in metabolism. Some proteins are digestive enzymes allowing the assimilation of food molecules; others form antibodies and enable the body to defend itself against external aggressions. Finally, proteins are also part of the composition of hemoglobin and certain hormones.
20 high protein foods
There are over 20 naturally occurring amino acids found in dietary protein. Nine are essential amino acids that the body cannot make. They must therefore be obtained through food. The other amino acids are nonessential because the body can make them.
|
Food |
Portions |
Quantity (g) |
| Chicken breast, cooked, skinless | 100 g | 31 g |
| Ground beef, lean, cooked | 100 g | 30 g |
| Pork, chop, cooked | 100 g | 29 g |
| Game meat, horse, cooked | 100 g | 28 g |
| Whitefish (cod, sole, cod) | 100 g | 23-26 g |
| Fatty fish (salmon, trout, mackerel, etc.) | 100 g | 23-25 g |
| Firm tofu | 100 g | 14 g |
| Firm cheddar-style cheese | 50 g | 11-12 g |
| Soybeans | 30 g | 10 g |
| Sliced ham/turkey breast | 2 slices (50 g) | 9 g |
| Milk 0, 1, 2% mg | 1 cup (250 ml) | 9 g |
| Almonds | 35 g | 8 g |
| Greek yogurt | 100 g | 8 g |
| Fortified soy beverage, all flavors | 1 cup (250 ml) | 6-8 g |
| Large eggs | 1 (50 g) | 7 g |
| Natural peanut /almond butter | 2 tbsp. soup | 5-7 g |
| Silky tofu | 100 g | 6 g |
| Whole wheat bread | 1 slice / 30 g | 4-6 g |
| Yogurt 0 to 2% mg | 100 g | 4 g |
| Quinoa, cooked | 75 g | 3 g |
How to use proteins well?
Protein requirements
| Population | ANC = Recommended Nutritional Intake (in g / kg / day) |
|---|---|
|
Babies 0-6 months |
1.52 * |
|
Babies 7-12 months |
1.2 |
|
Infants 1-3 years |
1.05 |
|
Children 4-8 years old |
0.95 |
|
Boys 9-13 years old |
0.95 |
|
Girls 9-13 years |
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 |
0.80 |
|
Men 50 years and over |
0.80 |
|
Women 50 years and over |
0.80 |
|
Pregnant women |
1.1 |
| Breastfeeding women |
1.3 |
* Insufficient data to calculate ANC; therefore sufficient intake (AI) was determined.
- 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 from protein. In France, people consume on average around 17% of their calories in the form of protein.
Complementarity of proteins
It is important to note that animal proteins (meats, dairy products, eggs) are complete proteins; they contain all the amino acids essential for the growth and maintenance of the integrity of the body. ‘organization. On the other hand, plant proteins do not contain all the amino acids in sufficient quantities to make them complete proteins. Soy is an exception to this rule, however, and includes all of the essential amino acids. To supplement vegetable proteins, there are several options:
- Combine a vegetable protein with an animal protein (ex: chilli con carne)
- Combine legumes (beans, lentils, chickpeas) with grain products (ex: couscous and chickpea salad)
- Combine legumes and oilseeds (e.g.: lentil and almond salad).
We believed that it was necessary to make these associations within the same meal for a long time to ensure complementarity. Recently, it has been shown that if complementary foods are consumed within 24 hours, the benefits of complete proteins are present. However, pregnant women should make these food combinations within the same meal.
The protein diet
There are many protein diets, and their indications are multiple. Increasing protein intake can be particularly recommended to fight against undernutrition or malabsorption phenomena. Likewise, in athletes, it may be recommended to consume proteins around weight training sessions to promote muscle mass development. This supplementation can be done naturally through the diet 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 validity in the long term.
Adverse effects of proteins
Consequences of a protein deficit
An adequate amount of protein each day must be present to prevent protein-energy malnutrition. Protein deficiency is very rare in industrialized countries but can occur in hospitals in people with a disease and the elderly. On the other hand, in developing countries, marasmus and 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 systems of the body, such as the brain, brain functions, immune system, and kidney function. Signs related to protein deficiency are edema (water retention or swelling), reduced muscle mass.
Excess protein
The risk of having excessive protein intake from food is shallow. However, some scientific studies 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 losing calcium from the bones or other adverse effects on bone health. Some high-protein diets are often very high in animal protein and therefore high in saturated fat. Consequently, it is not surprising to see in the literature the correlation between the consumption of red meat and dairy products high in fat and cardiovascular disease and certain types of cancer.
Necessary: People with chronic kidney disease and certain genetic disorders should continuously assess their protein intake and work with a dietitian to achieve this.
Interactions with other nutrients
The interactions between proteins and other nutrients are incredibly numerous. For example, they are the ones that transport the minor nutrients in and out of the body’s cells. In this sense, we can say that an optimal nutritional state is essential for the proper functioning of the whole organism.
Chemical properties
History of the nutrient
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.
For centuries, the multiple roles of proteins in the human body have continued to be highlighted by scientists.
