Macronutrients 101: Protein Function

Throughout times we have gone from low-fat to low-carb to now high-protein fad diets. You hear people saying “I need x grams of protein pre day” or see guys at the gym chugging protein shakes. It seems like the world revolves around “getting enough protein” and “having protein at every meal”. However, what exactly is protein and why do our bodies need it?

Proteins are the final products of our genes. Our DNA is nothing but a series of instructions for our bodies to manufacture proteins. The DNA sequence tells the order in which monomer amino acids are linked up to form a protein. This unique sequence of monomers will determine the overall shape of the protein and in turn its function.

There is a plethora of various protein functions but I though I’d go over some of the most common ones.

1) Structure

Long thin proteins like collagen, elastin, and keratin make up much of our connective tissues such bones, cartilage, and skin.

2) Transport

Proteins can be involved in systemic and cellular transport. Albumin plays a role in systemic transport as a carrier of water insoluble molecules such hormones in a water rich environment like blood. Similarly, hemoglobin is a systemic carrier of oxygen in the body. In terms of cellular transport, some protein are able to embed within the fatty cellular membranes. These proteins can then act as channels to allow certain molecules to pass through them into or out of the cell.

3) Molecular reactions

Enzymes are a type of proteins that allow for specific reactions to occur by reducing the reaction’s threshold energy. You can think of it as enzymes as something that will give molecules a “push over the fence” without which they wouldn’t be able to cross over.

4) Signal transduction

Proteins are involved in signalling pathways both as the signals and the receptors that receive these signals. These signalling pathways are vital for our bodily functions and range from embryonic development to metabolism.

5) Defense

An antibody or immunoglobin is a protein created by out white blood cells.

6) Movement

Of course, who could forget that proteins are important for our muscles.

As you can tell, the functions of proteins are highly diverse. Yet, if proteins are naturally made by our bodies then why do we need to consume them? Well it’s not necessarily the protein that we need but its building blocks, the amino acids. Once our own proteins serve their purpose our body breaks them back down to amino acids. Our kidneys are not perfect and a little bit of amino acids end up in urine. To replenish these amino acids we must get them from dietary protein sources.  All of the excess amino acids will not magically become muscles but will instead be burned for energy. Hence, don’t be fooled by all that whey protein garbage! To build muscle you need excess calories NOT bucket-loads of protein.

There we have it, the function of proteins. Technically, proteins aren’t an efficient energy source and you’re better off burning carbs or fats. In fact, protein metabolism produces a toxic byproduct called uric acid which is hard on our kidneys. However, I’ll save that for a future post 😉


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