In recent years, thanks to emerging research, diet books and popular articles, the general public is starting to become aware of something that many athletes (especially bodybuilders) have been saying for a while: higher protein diets are better for weight/fat loss and improved health. In addition, athletes have long been on the search for nutrients or foods that can improve their performance or their adaptation to the training they put themselves through.
Between those two groups, a question that often comes up is “What are good sources of protein?”
Many websites offer simple answers to that question, generally revolving around whatever protein they happen to sell; the answer, as always, is far more complicated than that. A large number of variables go into the declaration of what a good source of protein is and, as always, what is good in one context may not be good in another.
That is to say, the decision over what a good source of protein happens to be is entirely context dependent.
So, in my usual way, I’m going to dissect the question and look at all of the factors that go into determining what constitutes a good source of protein. In this first part of this article series, I’m simply going to introduce and define some terms, I’ll look at each in detail in forthcoming parts of this series (over the next few days).
Before continuing, I’d mention that this topic was of sufficient interest to me that I wrote an entire book on the topic, The Protein Book. Much of what I’ll be presenting will be excerpted from that project.
I’d also note before continuing that there is still a lot of very outdated information about the ‘dangers’ of high-protein diets. I address them in detail in the article Protein Controversies, on this site. And with that out of the way, let me start answering the question “What are good sources of protein?”
The topics I’m going to discuss in each of the following articles, relating to what makes a protein source good (or bad, or middling) are the following:
Digestibility: Before a protein can be used by the body, it has to be digested and absorbed into the bloodstream for use by the body. Proteins vary in their digestibility and, logically, a protein that is poorly digested will be a poor source simply because less of what’s being eaten is being made available to the body. A topic related to digestibility is the speed of digestion and there has been interest since about the late 90’s in how a given protein’s digestion speed affects how it is used by the body.
Protein Quality: In one sense, the topic of protein quality could be used as an overall look at many of the other topics I’m going to discuss. In general, protein quality is a measure of how well or poorly a given protein is used by the body. I’d note that how you define the word ‘use’ here depends also on context. Are we talking about a protein’s ability to sustain life, build muscle, improve performance, improve health? Some measures of protein quality take into account digestion while others do not (which is why I’ll discuss digestion separately), the amino acid profile of the protein tends to be one of the biggest determinants of quality.
Amino Acid Profile: Again, tying in with the issue of protein quality, there is the issue of the amino acid profile of a given protein. For background, amino acids are simply the building blocks of protein, and there are 18-22 distinct amino acids depending on who you talk to (not all sources recognize all of the amino acids). Each one is found in differing proportions in different food protein sources and, under certain circumstances, that profile will affect how it is used in the body or how it functions.
Presence or Absence of Other Nutrients: While often ignored, the presence or absence of other nutrients in a given protein source also impacts on how good of a protein it may be. For example, some protein sources contain high levels of iron, B12 and zinc while others do not; the presence of absence of the omega-3 fatty acids (fish oils) may also be relevant. Calcium is also a consideration.
Other Factors: There are a number of other potential factors surrounding protein that might determine which is a good or bad source under a given context. For example, proteins may show different effects on appetite, or blood sugar control, or what have you. There is also the issue of cost and availability along with the amount of protein in a given amount of whole food proteins. I’ll cover those as a catch-all final category in this series before summing up and looking at a variety of whole food proteins and how they rank on each category.
So those are the major topics I’m going to cover in this series of articles. While it will take a bit of time to cover all of the information I want to cover, by the end of the series you’ll know the answer to the question “What are good sources of protein?”