What are proteins and why are they so important? Here’s everything you need to know.
WHY THEY ARE SO IMPORTANT
Alongside carbohydrates and lipids, proteins are one of the three macronutrients that make up all cells and tissues in the animal body.
But proteins don’t only have a structural function. In fact, theseare also essential for the animals’ immune system, for example, antibodies are proteins (gamma globulins).
Another key function is transport. The two main transport proteins are hemoglobin, which carries oxygen in the blood, and albumin, which acts as the “transport company” in the blood.In our animals, it works like a carton which many hormones, fats, minerals, and medications are loaded and transported.
HOW ARE PROTEINS MADE?
There are thousands of different types of proteins. To give a simple example, it’slike Lego builds where the small pieces that make them up are called amino acids. There are thousands of proteins, but most are built from just over 20 amino acids. Some of these can be produced by the animal body (for example, in the liver), while others must be obtained through diet. The latter are called “essential.” There are 10 in dogs and 11 in cats.
For example, in dogs and cats, essential amino acids include arginine, methionine, tryptophan, and lysine (found in both animal and plant proteins). In cats, we also have taurine, which must be obtained through diet and is only found in animal-derived proteins (one of the reasons cats are obligate carnivores)
So when animals eat protein through their diet, digestion breaks it down into amino acids, which are then used to build the proteins they need. If there are extra amino acids, they aren’t used for building proteins—instead, they’re used to produce energy.
WHAT ARE THE BEST PROTEIN SOURCES FOR DOGS AND CATS?
At this point, we need to introduce the concept of“biological value” of proteins. As a general rule, proteins with the highest biological value are those most similar to the proteins found in the bodies of the animals that eat them. It’s easy to see howanimal-derived proteins (in meat, fish, eggs, milk, and dairy products), unlike those from plant sources (grains, legumes, fruits, and vegetables), can be considered“high-quality proteins” (with higher biological value).
These proteins contain all amino acids (including the essential ones) in optimal proportions for the synthesis of new proteins. Plant-based proteins, on the other hand, have an amino acid pool with less ideal proportions for the synthesis of new animal proteins. Essential amino acids may be deficient or completely absent, as is the case with taurine.
Thetaurine deficiencyleads to several consequences:
- disruptions to reproductive function, especially in females
- Reduced absorption of vitamins and fats.
- Vision problems, as it is essential for the retina.
- It is important for heart muscle; a deficiency could lead to dilated cardiomyopathy and subsequent heart failure.
Dr. Simone Falci
Veterinarian, expert in nutrition