We know that essential amino acids (indispensable amino acids) need to enter the body via the diet, our bodies lack the ability to make these internally meaning we have to ensure the sources of protein we consume either tick the boxes individually or cumulatively. I will explain shortly…
We therefore base the quality of a protein source on its ability to deliver all 8 of the essential amino acids, namely:
Enter the humble Egg
Eggs deliver every single one of the essential amino acids, and it delivers them in the most readily available form, well apart from whey protein, but we will come to this in a moment.
Such is the quality and completeness of the protein in egg, it became the standard by which all protein sources were compared. This was given what’s known as the biological value (BV) or bioavailability of protein. Egg was considered the complete protein source containing all essential amino acids and readily absorbed by the body giving it a BV of 100, as good as you can get…until whey protein powders came about!
Whey protein is so readily up taken by the body that its BV value had to exceed 100 and was therefore given the respective BV of 104. Odd I know, and underlines the ever evolving field of nutrition science.
However, despite whey protein being a great source of protein, it is little other than protein, whereas the egg delivers 5g fat (which is a good thing), iron, carotenoids and vitamins A, D and B12 to name a few.
So eggs have it all, you could eat no other source of protein and thrive quite nicely on a few eggs a day, but who in their right mind would want to do that. A healthy diet requires variety, so it is nice to get some protein from meat, fish and even plant based sources such as beans, peas, pulses, lentils and so on, only problem is that these are literally limited by certain essential amino acids.
Limiting Amino Acids
Take beans as an example, a useful and legitimate source of protein in its own right, but it isn’t a patch on the humble egg as it is missing Methionine, one of the essential amino acids our body cannot make itself AND needs to enter through the diet!
Nuts and seeds deliver way more than just protein, but with respect to the quality of protein, they do lack the essential amino acid Lysine. Vegetables are another legit source of protein however you could eat a mountain of veg and NEVER actually meet your requirement for all 8 essential amino acids due to them lacking Methionine.
You see the pattern here? But there’s a but, although plant based sources of protein may lack some of the essential amino acids on their own, there is nothing stopping you from getting them in through combinations of plant protein. For example, if you consume beans as a protein source you will lack Methionine, so combine these with a serving of nuts and seeds which DO contain Methionine, then you cover yourself.
I hear you, it is a bit faffy, so if you can, get a combo of protein sources to ensure you cover all bases and don’t fall foul to limiting amino acids. The egg is king because it has you covered in all areas.