Macronutrients: Proteins

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Proteins

Proteins are large organic molecules consist of carbon, hydrogen, oxygen, nitrogen, and some also by sulphur. They constitute 20% of the human body, being their essential presence for growth in children and in adults, pregnant women and old age maintenance.
The word protein comes from the Greek protos meaning first, since it is a basic component in our agency, being responsible for the formation of muscle.

Need of protein in the diet

People ranging through various stages in its life: childhood, adolescence, adulthood and old age. In addition, in the case of women, you can also pass by one or more pregnancies. That is why, according to the time of our lives, we will need a different protein intake.
The necessary contribution of protein a day to follow a balanced diet is between 12-15% of the total energy.
Children and adolescents need more protein than adults because they are in full development.
Pregnant or breast feeding, women also need a greater intake of protein compared with the woman who is not in the making, since they must meet the needs of the developing baby and make the milk secreting proteins mother.

Function of proteins

The main function of protein is structural or plastic, i.e., we help to produce and regenerate our tissues. I.e., if we compare our body with a House, proteins would be bricks, along with foundations and shingles.
However, in addition to this function, they play others such as:

• Energy: when the intake of carbohydrates and fat from the diet is insufficient to meet the energy needs in the event of a prolonged fasting, the degradation of proteins (amino acids) will cover these shortcomings.
  
• Regulator: there are proteins, e.g. insulin (growth hormone), involved in the regulation of many processes.
  
• Transport: for example, hemoglobin, is responsible for transporting oxygen; or albumin transports fatty acids free.
  
• Defense: this type of protein helps the body's defenses protecting the body from certain foreign agents or exterminating them. An example would be a immunoglobulins.

Protein sources

Then we tell you what are the foods that are the best sources of protein:

Food of animal origin

• Egg: It is a good source of protein since it contains the albumin, of excellent quality, since it includes a high amount of essential amino acids.
  
• Fish (salmon, herring, trout...).
  
• Milk.
  
• Dairy products, cheese, or yogurt.
  
• Lean beef, Turkey and chicken.

These foods contain proteins with a high number of essential amino acids (those who can not be synthesized by the body, so it must be provided through the diet).

Food of plant origin

• Legumes (beans, lentils, chickpeas, beans...), should fill them with other food such as potatoes or rice.
  
• Green leafy vegetables (Kale, spinach...).
  
• Nuts and dried fruits (as long as they are not fried and have little or no salt).
  
• Seitan, tempeh, quinoa, algae.

The proteins that contribute to the organism food of plant origin, such as legumes, are inferior to those of animal origin because they present less essential amino acids, something that is offset with a proper mix of both.
Adult should eat a protein contribution suitable to their way of life, i.e., if you have a higher activity, will need greater contribution than a sedentary adult.
In the third age, still seeming contradictory, don't need a lower protein intake, but it is recommended to increase the amount of them, because at this stage it is very important to regenerate tissues. In addition, should take into account the possible emergence of chronic diseases which can degrade proteins.

Article contributed for educational purposes