When it comes to protein, not all sources are the same. While some proteins are more easily absorbed by the body than others, the amino acid profile and bioavailability of proteins from any food source you consume will determine how much nutrition you actually get from it. Legumes, particularly soy, are the best vegetable sources of protein in terms of quantity, amino acid profile and bioavailability. Bioavailability is the percentage of protein that is absorbed from certain sources.
Our bodies and digestive systems absorb some proteins better than others and certain sources also provide a higher amino acid profile. Many people, including myself when I first started out, have the impression that a protein is a protein, period. On the one hand, you would need to consume a massive intake of those food sources to get your daily protein needs and even if you could, you would overconsume total calories, which would inevitably lead to an increase in fat. A protein with high bioavailability is easily absorbed after digestion and a high percentage of amino acids can be used by the body. Depending on the type of protein ingested, the bioavailability of proteins can change dramatically.
By refining sources such as whey or pea protein, the bioavailability of that protein can be improved to a greater or lesser extent, depending on the technology used. The amino acid profile and the bioavailability of proteins from any food source you consume will determine how much nutrition you actually get from it. Another commonly used metric to measure protein quality is the PDCAAS (score of amino acids corrected for protein digestibility). Egg protein powder is generally made from egg whites rather than whole eggs, and while protein quality is considered good, whey protein powder is considered superior due to the higher volume of leucine. Many plant-based proteins (but not all) are low in several amino acids, especially leucine EAA. Secondly, proteins are made up of essential amino acids and non-essential amino acids, but most of the proteins that can be found in the foods mentioned above are not “complete” proteins and lack one or more essential amino acids that the body needs.
The next time you see a food product on the shelf boasting about its protein content, think twice about its source. In conclusion, when it comes to getting enough nutrition from your diet, it's important to consider not only the quantity but also the quality of your protein sources. Different types of proteins have different levels of bioavailability and amino acid profiles. Refined sources such as whey or pea protein can improve bioavailability while egg or soy proteins may provide a higher amino acid profile. Ultimately, it's important to consider both factors when selecting your protein sources.