What is protein?
Protein is a biological compound found throughout the earth consisting of amino acids held together by chemical bonds in specific patterns. In terms of human biology, protein is one of the 3 main sources of nutrients (called macronutrients) used as a building block for tissue bone and plasma, it is also used for energy in certain cases, lastly protein can also be used to create enzymes that facilitate chemical reactions in the body.
Different types of dietary protein important to humans
There are many amino acids, but there are 20 that are vital to humans and required for proper nutrition and health. Of these 20 there are 8 amino acids that cannot be synthesized from base components already in the body. These 8 amino acids are called essential amino acids, and must be acquired through diet and/or supplementation. Aside from the amino acids, different nutritional elements provide different “types” of protein (whey, soy, casein, hydrolysate …). Some proteins are delivered faster to the systems that need them than others, and some proteins are closer to a usable state and require less break down from digestion, the less time and energy required to break down proteins and rebuild them, the quicker they can be used in the body for things such as muscle building, enzyme creation, and muscle contraction.
How we use protein
Generally speaking, protein metabolism consists of ingestion of protein from a plant or animal source, breakdown of the protein into component amino acids in the digestive system, transport of the component amino acids to their desired location, and rebuilding of the right protein structures in the cells at the site needed. When protein levels are sufficient and of the right type, extra protein is used as an energy source, either through Gluconeogenesis or the Krebs cycle, and eventually either being used for energy creation or storage (storage meaning after the breakdown of the protein it is then passed further along the metabolic process and participates in lipogenesis and fat storage similar to excess carbohydrates).
It is important to note that the human body does not see protein as a primary fuel source, rather carbohydrates, and in the absence of carbohydrates, fats are both considered better fuel sources than protein. In general there are two main situations where protein will be tapped as a primary fuel. The first being lack of incoming calories, and the inability of the body to make up the fuel shortage with fat. Our body can only draw so much fat at any one time; chemical limitations mean there’s a cap, if the deficit seen is greater than that amount, then protein can be tapped as a reserve fuel source. Please note that this reaction will also trigger other, less beneficial changes in the body if allowed to continue for extended periods. The second situation where proteins are used as energy is when more than enough protein is being consumed. The body will not store extra protein in its main form. Any amino acids that have no immediate use will be broken down by the processes stated above and used as either energy if necessary, or stored as fat.
Benefits of protein
Protein as a nutrient is important because it helps keep muscles healthy, is required to have adequate muscle contraction, and important for many body functions. When we exercise our muscles beyond their normal capacity, the body recognizes the need to increase work capacity of muscles, this means growth. Muscle growth requires amino acids to build current muscles, and repair muscles that have been overworked, this is a slow process, and you don’t gain pounds of muscle in weeks (in fact, 1 pound per month of muscle growth is considered aggressive over the long term). A complex series of chemical reactions need to occur in the body in order to facilitate wide range muscle growth, while the body will always attempt (and prioritize) repair of existing muscle, building new muscle will only happen if there is both need and available resources. This is why persons in a prolonged, significant caloric deficit will generally not build new muscle mass. While there are very specialized situations where it CAN happen, it is not the normal process.
Drawbacks of protein
The breakdown of dietary protein can have adverse effects on the body. Protein that is not used for muscle growth, repair, or other direct amino acid uses is broken down into component carbon chains. This breakdown releases chemicals into the body that need to be flushed and removed because the body considers them poisons. Much of the breakdown and rebuilding of amino acids is done in the liver and Kidneys. Eating large amounts of protein, over and above the requirements of the body for building blocks will trigger the liver and the kidneys to “work” harder. Because these two organ sets are the main filters for un-wanted chemicals in the blood, they are the primary concern when ingesting large amounts of protein for long periods. For those with blood disorders, family history of liver and/or kidney problems, and other filtration related issues, protein consumption should be very closely monitored.
Suggestions and conclusions
Over the last 20 or so years, there’s been a large push to increase protein intake, especially among high intensity athletes (body building, strength related sports, weight lifting), but in most industrialized nations, protein consumption is well within requirements to maintain optimal health. Most nutrition organizations recommend approximately between 1 and 2 grams per kilogram of protein (about .4 to .9 grams per pound). There’s very little credible evidence that any amount above that is used for muscle growth and other amino acid direct delivery. The range is generally determined by age, sex, activity level, and exercise types and level. Please note that these levels apply to fully developed adults, teens and children and people of advanced age require different quantities of macronutrients.
Vegetarians are especially susceptible to protein deficiencies and need to make sure they “complete” their protein intake (by taking in foods with all the essential amino acids required by the body for protein synthesis). Vegetable sources of protein quite often only deliver some of the essential amino acids required to build specific proteins. While many times the body will have the remainder of those amino acids available to combine with them and complete the proteins, with vegetarians, this is not always the case. For vegetarians, research into which amino acids a protein source has and what other plant based sources to combine with them is vital to remaining healthy. While the sources are not difficult to find and combine, often vegetarians fail to do so, and thus can develop problems as a result.