The entire body is replaced almost every year through the natural process of cell death and replacement. Muscles, internal organs, enzymes, hormones, antibodies and red blood cells are all made of protein, which the body must derive wholly from the diet in order to rebuild. Just like inferior lumber makes an inferior house, a soda and chocolate bar diet makes a soda and chocolate bar body. The quantity and quality of protein you eat is very important to ensure healthy cell formation.
Proteins are made up of amino acids, and each amino acid has a nitrogen molecule in it–something that neither fats nor carbohydrates have. When protein is used as fuel, or when muscle or some other functional protein comes to the end of its useful lifespan, its nitrogen is flushed out through the kidneys in the form of urea.
How much protein are you consuming? Biochemists refer to this calculation in general terms as a positive or negative nitrogen balance. By comparing the amount of nitrogen consumed by a given person to the amount flushed out during excretion, a scientist can determine whether the person’s nitrogen (protein) level drops, increases or stays the same.
Evaluating Protein Intake
A negative nitrogen balance means that you are not getting enough protein. If you are in negative balance, your body cannibalizes your muscle tissue to provide the protein necessary to manufacture blood, enzymes and hormones. If this starvation continueslong enough and severely enough, eventually the protein-forming internal organs is cannibalized to the point of organ malfunction and death.
Fortunately our bodies are ingenious at making do with insufficient and inferior protein sources and irreparable damage generally occurs only under the most extreme conditions. But getting too much protein can also cause problems. In this case, the nitrogen from the excess protein is converted to toxic ammonia. Blood poisoning can occur if the kidneys are overloaded and cannot clean the blood fast enough. This condition is also rare and generally occurs only in weight trainers who are under the misguided notion that infinite protein provides unlimited gains in muscle size and strength.
How much protein is enough for you? If you are consuming your optimal amount, muscle mass is gained with strength training and not lost with endurance training. You should also feel energetic. The official recommended daily intake of protein is 0.8 grams per kilogram of body weight. A 200-pound man (91 kilograms) should require only 73 grams of protein per day. (That’s less than the amount of protein in a can of tuna fish!)
A few good studies now indicate that even a moderate amount of exercise dramatically increases your need for protein, especially if you are doing resistance exercises like weight training. In fact, a number of prominent sports nutritionists recommend 1.5 grams of protein per kilogram of body weight for those who are training daily. Of course, there is quite a bit of individual variation, depending on lifestyle and individual metabolism.
Healthy Protein Sources
Of the 20 or so essential amino acids that the body uses to build proteins, there are eight we cannot make ourselves and must get from the diet. Another two we frequently can’t produce during times of stress.
Fish, shellfish, eggs, milk and some nuts provide highly digestible protein with plenty of essential amino acids. Plant protein sources are usually incomplete, with two or more amino acids missing, but that does not mean that you cannot obtain enough high quality protein from purely plant sources–you just have to eat a variety of vegetables. Soy is an exception–fermented soy foods are a particularly good source of complete proteins.
Another bonus for vegetarians is the fact that protein from beef comes with too much unhealthy fat. Those relying on vegetable sources of protein must make sure to eat fresh, whole grains and beans, since processing strips most of the protein and other nutrients from food sources.
A common belief is that plant proteins must be carefully planned at every meal to achieve the right combination of amino acids. However, the body is quite adaptable. When large quantities of one or two amino acids are taken at a meal, they are stored in the spaces between the cells of our muscles until they are needed to balance the lack in a subsequent meal. So as long as you get sufficient amounts of the essential amino acids over about 24 hours, your body can compensate. The needs of children are more demanding; they should consume correct combinations of essential amino acids within about six hours.
Overall, you must make your protein choice based on individual requirements. Combine a good source of protein with sufficient complex carbohydrates, fresh-pressed, unrefined seed and nut oils and regular exercise. The result will be a body designed for good health.