Carnivores and Herbivores Alike, Listen up!
By: Jared Miller
Protein… the buzzword of the fitness community. Protein gets a lot of attention these days. Product labels tout their ‘high protein’ contents as if high protein content is synonymous with being ‘healthier’ food choices, such as high protein breads, pitas, tortillas etc. ‘Greek yogurt’, seemed to be promoted as a female fitness fad for about a year or so, with all the commercials and pictures of women enjoying low fat, high protein Greek yogurt. I am somewhat cynical about some industrial food companies, their products and their use of wording to promote their products that may sometimes resemble the foods that sustained our ancestors, but have very different chemical balances. Let us take a more objective examination of what protein actually is, and then it will be possible to form an opinion that is more complete and fact based, and less based on diet folklore.
What is Protein?
Proteins, also known as peptides, are a classification of molecules commonly found in biological (living) materials. Proteins exist in nature outside of living organisms, but for the sake of this article, we will focus on protein as it relates to human nutrition and physiology.
Many structural and functional components of the human body are composed of protein. For instance, structural components such as bone are made from a combination of inorganic salts, such as calcium phosphate, and a matrix (web) of protein to hold it together. Functional components of the human body such as the hormone insulin are also made of protein. There are literally countless numbers of examples of protein being vital to human function, and there are upwards of 10,000 known, unique proteins in the human body, each with a particular function.
Proteins are made of subunits called amino acids, and proteins can be made of as few as two amino acids linked together by a peptide bond, or thousands of amino acids, known as a polypeptide. The body does not have any designated storage compartment for protein. Unlike glycogen contained in the liver and muscle, or fat contained in the adipose tissue, all protein in the body is functional. The muscles, bones and other structures are abundant in protein, and they are serve a function.. Similarly, enzymes, cellular receptors and some hormones are made of protein and are all over the body at any given time performing their functions. This means that proteins of various kinds are constantly being cycled through the body.
Protein Metabolism ‘In a Nut Shell’
Recall the concepts of anabolism and catabolism from the article on carbohydrate requirements. When protein is ingested, it is catabolized into individual amino acids by enzymes (made of protein themselves) in the gastrointestinal tract so that amino acids will be absorbed into the intestines, and transported to the liver for processing. Amino acids travel around the body, and provide components for cells to make proteins. When cells create protein from amino acids, these are anabolic processes. Eventually, proteins will be cycled through the body, performing their many different functions and ultimately being catabolized, with some components being excreted in the urine and some components being recycled by the body. Similarly to carbohydrates, the concept of balance is important when it comes to understanding protein in the body. The simple way to view protein requirements is to consider the concept of nitrogen balance. Since proteins contain nitrogen, and nitrogen is constantly being excreted in the urine in proportion to how much nitrogen is being cycled through the body (excreted as urea, the substance that gives urine its colour). This contributes to a negative nitrogen balance (a loss of nitrogen). In contrary, ingesting proteins, which contain nitrogen, contributes to a positive nitrogen balance (a gain of nitrogen). Therefore, people who are growing would be in a positive nitrogen balance, people who are maintaining would be in a neutral nitrogen balance, people who are undernourished and consequently, deteriorating, would be in a negative protein balance. Unfortunately, there are many people within our communities who spend long periods of time in a negative nitrogen balance, due to circumstances such as poverty or poor food supply. This leads to protein malnutrition, which can lead to many complications. Since the body is a transient being, it will naturally fluctuate between positive and negative nitrogen balances throughout the day, but that is primarily influenced by protein intake in the diet, and metabolic rate.
There are basically 20 amino acids in the human body. There are 9 amino acids that are known as ‘essential’ amino acids because it is essential that they be consumed in the diet under all circumstances. There are 6 amino acids that are considered to be ‘conditionally essential’, because they may become essential in the diet under specific conditions, such as after very strenuous exercise. There are 5 amino acids that are referred to as ‘non essential’ amino acids because they are produced by the human body naturally, and their production is coded for in our DNA.
- Essential Amino Acids must be consumed in the diet in order for the human organism to synthesize (create) proteins that serve vital functions. All of the essential amino acids are found in sources of protein derived from animals. Therefore, dairy products, meat, poultry, fish and eggs are sources of all the essential amino acids. Protein sources containing all of the essential amino acids in adequate quantities are known as complete protein sources. Protein sources derived from plants may also contain all of the essential amino acids on their own, and these include sources like chickpeas, quinoa, cashews, and hemp seeds. However, many plant sources do not contain all of the essential amino acids in sufficient quantities on their own, but combining different plant sources together such as corn and beans can create a full complement of amino acids, and this is of particular importance for vegan and vegetarian eaters who will have to find good sources of essential amino acids from plant matter. Granted a person is eating animal sources of protein, there is very little concern for lack of essential amino acids in the diet, however as mentioned, vegan and vegetarian eaters need to be mindful that they are consuming protein sources containing the essential amino acids. The names of the 9 essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
- Conditionally Essential Amino Acids can be produced by the human body, but under special circumstances, the body may not be able to produce enough to fulfill the needs of the body, and these amino acids become essential under these conditions. Most of these conditions include conditions of metabolic stress in the body, such as after/during very strenuous exercise, during longstanding illness and severe wounds or burns (including sunburn). For the most part, the average person that is free of ailments will be consuming enough of these amino acids in their diet to fulfill their needs. Since there is a difference between eating for health and eating for performance, special consideration may be necessary for individuals participating in advanced or elite training for sport; however, the vast majority of gym-goers simply do not fall under this distinction. In essence, there are few considerations regarding this category of amino acids, since they are not considered essential under normal circumstances. It is likely that a person eating a variety of protein sources will be fulfilling their requirement for these amino acids even if they have above-mentioned conditions. Depending on the source of information, the names of the conditionally essential amino acids are arginine, cysteine, glycine, glutamine, proline and tyrosine.
- Non-Essential Amino Acids can be produced in sufficient quantities by the human body under virtually all circumstances, because they are coded for in the DNA, and are made from available materials. This means that they do not necessarily have to be consumed in the diet. Nonetheless, they are present in many protein sources that are going to be consumed regardless. There are not many things to consider regarding these amino acids. The names of the non-essential amino acids are alanine, aspartic acid, asparagine, glutamic acid and serine.
General Guidelines for Protein Consumption
Proteins are essential nutrients in the diet because they form critical components of the human body. Proteins could be considered the most important macronutrients because they are the only nutrients that can be converted into other substances by the liver to create glucose, fat, hormones, and neurotransmitters among others, in the absence of other macronutrients.
Protein requirements are relatively higher for individuals who are in stages of physical growth in their life. A mother’s milk or infant formula are high protein sources for growing infants, as well, children and adolescents experiencing growth spurts will have relatively higher protein requirements to provide them adequate structural and functional components to reach their growth potential.
Individuals participating in athletics will have higher relative protein requirements than when they are sedentary.
Individuals on a weight-loss diet will have higher relative protein requirements than those on a weight maintaining diet, because of the needs to preserve muscle mass in a potentially Calorie deficient state, accompanied by an appropriate exercise regime.
Individuals on a weight-gain diet will have higher relative protein requirements in order for their weight gain to be more lean mass, and less fat mass, accompanied by weight training centered around hypertrophy (growth) of the muscles and lean tissues.
Vegan and Vegetarian eaters should pay special attention to their protein intake because it is a little more difficult to obtain enough protein, and particularly essential amino acids in their diet.
In all populations, protein requirements will vary between individuals.
*Some individuals participating in resistance training believe in the need for supplemental protein in their diet i.e. protein shakes. But it is completely possible to meet protein requirements with natural foods in the vast majority of people partaking in resistance training. Only objectively advanced and elite athletes can really say that they need protein supplements, and that is still considered debatable among authorities in the field of strength and conditioning. Nonetheless, if you are taking supplemental protein and it seems to make a notable difference, don’t fix it if it isn’t broken.
When it comes to protein recommendations made in a bodybuilding magazine, on a product label or in a ‘nutrition store’, be aware that some of these recommendations are for people who are typically training very frequently and may be taking anabolic agents to increase their muscle mass beyond normal levels.
So then, can a product label tout protein as being a healthy, vital nutrient? Sure, just be aware that a highly processed product with some type of added protein is not necessarily a healthier product than the regular variety. It just has more protein in it. Protein does not promote health all on its own, but also the vitamins and minerals that are abundant in ancient protein sources like good quality dairy, meat, poultry, fish, eggs, nuts and seeds.