In the last Blog post (‘What do you actually know about food?’) I talked about the basic nutritional groups and highlighted the difference between micronutrients (vitamins and minerals) and macronutrients (protein, fat and carbohydrates). I said that I would be delving into each group a little more in later blogs, and so… here we are, discussing protein!
Protein – the building blocks of life!
Honestly it’s hard to overstate the importance of protein in the body. With a diet that lacks protein – even one that is rich in carbohydrates and fats – you will die a slow and painful death as your body will not have the basic materials it needs to repair itself and to fight off infection. Also, every enzyme in the body is a form of a protein. Since we need enzymes to facilitate almost every chemical reaction occurring in our bodies, you can see just how critical enzymes are.
Like carbohydrates and fats, protein can also be utilised for energy for living, not just for cellular repair and function. However, due to the structural nature of protein, it takes energy to actually break the protein down into a form we can use for energy. In other words, lets say you eat a portion of cooked chicken. It can take up to 25% of the energy in that chicken to break down the protein itself. Once the protein has been broken down, your body can use it for either energy to live or as building blocks for cellular repair, or as building blocks to create immune system antibodies or enzymes. However if there is not enough energy in the system, then the body MUST use the protein as energy to live, leaving it short on building blocks it needs elsewhere.
So what exactly is a ‘protein’? A protein is a looooong chain of different amino acids, all bound together with ‘water bonds’ (i.e it takes water to undo the bonds and free the amino acids). Each chain may be over a million amino acid units long and since only the amino acids and not the complete proteins can be absorbed across the gut wall, you can see how the protein chain must be completely dis-assembled in the gut, before the body can use it.
Basically, if you imagine a set of ‘Lego’ blocks, in 20 different colours (there are 20 different amino acids that make up all proteins), then you are half way there. Now imagine that the chicken you just ate was made up of millions of those lego bricks, in all different colours. Now imagine that the lump of blocks has to be completely ‘destroyed’ into its component blocks before anything new can be created, and you have the basic ‘protein amino model’. In other words, protein may be hugely varied in its ability to create new structures, but it can only do so, if it has first been broken down into its most basic units.