Proteins were named one and a half centuries
ago after the late greek world “πρωτεῖος” (Proteios), which means, ‘of primary importance’.
The name is well-deserved because proteins are capable of accomplishing truly amazing
things in our body. No wonder that for many people, proteins are the “king” of nutrients.
But this idea of primacy has also created some die-hard misconceptions that still lay
in the back of the mind of many consumers. And I’d like to start our discussion of
proteins by pointing out three of these common misconceptions. The first one is that “protein is the good
stuff”, sort of the reason why you eat, what you really should be looking for in food,
to grow and stay strong. This idea dates back to the origins of the science of nutrition,
in the nineteenth century, when many scientists indeed believed that the reason we need to
eat is to get protein. But at this point in the course, you already know better. You know
for example that carbs and fats are equally as important. We can’t survive without the
essential fatty acids. We need many vitamins and minerals. Without fiber and other non-nutrient
bioactives our health would be suboptimal. Proteins are of primary importance, but they
are not the “only” important thing. Another common idea is that “protein is
animal”, meaning that animal food is the only source of high quality, bioavailable
proteins. Animal food is indeed an excellent source of protein, but it’s not the only
one. We can get all the proteins we need also from vegetable food, which is the reason why
so many people can perfectly thrive on vegan diets without any problem of protein deficiency. The last misconception is that protein “makes
muscle”. Well, protein does not. Exercise makes muscle. We do need a little bit more
protein to sustain muscle growth, but protein by itself does not have any anabolizing effect.
It doesn’t stimulate muscle growth. Just like we need bricks to build a new house,
but if we just throw there a bunch of bricks and do nothing else, we are not building anything.
If we eat more proteins and do nothing else, our body will just take those extra proteins,
convert them to fat and store them into our adipose tissue, which will make us fat, but
certainly not athletic. So now that we have clarified what’s false
about proteins, let’s move on and see what’s true.
Proteins are the molecules through which the cells in our body are able to express the
genetic information contained in our DNA. DNA is the blueprint of life: it contains
all the instructions to build our entire body and to make it work smoothly. But DNA only
provides the instructions. What executes these instructions is proteins. By synthesizing
proteins our body is able to translate the coded information contained in our DNA, into
actual working material to accomplish structural and regulatory roles. Proteins are the main structural material
in our body. Almost 20% of our body weight is accounted for by proteins. Our muscles,
our bones, our skin, all of our organs, our hair, our nails, protein is the stuff all
these things are made of. But there’s much more than that. Proteins
also have countless regulatory functions in our body. All the enzymes, carriers, transporters,
many hormones, signaling molecules, antibodies, all these regulatory molecules in our body,
are proteins. We need them to fight off infections, to contract our muscles, to digest and metabolize
what we eat, to detoxify toxic substances, and hundreds of other things. Proteins are
vital to virtually all of our metabolic processes, they not only give us structure, but they
also make all of these structures work. And then, proteins can also be used for energy.
We already know that they provide about 4 kilocalories per gram, just like carbs. However,
using proteins for energy is kind of a waste, because they are can be used for much more
‘noble’ structural and regulatory purposes. As we will learn, our body doesn’t really
like to use proteins for energy and unless it’s strictly necessary, it will spare them
for other more important structural and regulatory uses.