This paper provides the definition of “complete protein” and includes the food sources of complete protein, as well as its functions and benefits in the human body.
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According to the Harvard School of Public Health, protein constitutes “75% of our total bodyweight without the water (2008)”. Protein is a component of almost every tissue in our body. Furthermore, it “makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood (Harvard School of Public Health, 2007)”.
Protein, by definition is composed of several amino acids. Nine of which are called “essential amino acids” while the remaining are called “nonessential” and are “manufactured by the human body (Attwood 1997)”. The amino acids produced by the human body will not transform into protein unless the essential nine amino acids are present. Complete protein contains all nine essential amino acids. The nine amino acids are as follows: “Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan, and Valine. (Nutrition Research, 2008).” Meanwhile the following make up the nonessential amino acids: “Alanine, Arginine, Aspartic acid, Cysteine, Cystine, Glutamic acid, Glutamine, Glycine, Proline, Serine and Tyrosine (Nutrition Research, 2008).”
Animal sources are the best source of complete proteins and are said to have “high biological value. Biological value of a dietary protein is determined by the amount and proportion of essential amino acids it provides (Nutrition Research, 2008).” Examples of animal sources with ample amount of complete proteins are “eggs, fish, meat” and chicken (Kaufman, 2008). “Dairy products such as cheese, yogurt and milk can be good sources of complete proteins as well (Collier, 2008).” Only a few vegetables and other plant sources contain complete proteins. Beans however are said to be rich in the nine essential amino acids. Plant sources, in general, do contain amino acids but lack 1 or 2 essential ones, thus, referred to as incomplete proteins.
Though animal sources such as meat are a source of complete protein, Attwood maintains that “Meat is not necessary to ensure a supply of complete proteins” (1997). He claims that the trend nowadays is that most Americans get their proteins from animal sources and less from vegetables, fruits or grains. He further says that such trend “has been accompanied by a steady increase in heart-disease and cancer deaths” (Attwood, 1997).He states that though most vegetables or proteins lack the essential amino acids, but certain combinations can create complete proteins. Meanwhile, Collier maintains that “fish was a substantial source of complete proteins” and suggests eating red meats no more than one time per week and fish and poultry three or more times per week” (2008). In addition to this, Fernstrom emphasizes the importance of protein as one of the “three macronutrients together with carbohydrates and fat (2006).” She reminds that all there three should be maintained otherwise will result to imbalance.
Moreover, Julian Kaufman maintains that one can combine incomplete proteins into one’s diet in order to provide the body complete protein (2008). He says that it does not necessarily have to come in one meal, “as long as it is taken within a one or two day period (Kaufman, 2008)”. For instance, one can combine vegetables and a chicken viand to ensure consumption of complete protein. Also, when one source of incomplete protein is combined with another incomplete protein, it can make up as complete protein. Furthermore, he says that “the top five sources of complete proteins are fresh wild fish, all-natural yogurt, free range eggs, almonds, and soybeans (Kaufman, 2008).”
Benefits of Complete Protein
The human body is made up different cells and tissue. The “blood, muscle, bone, organs, arteries, veins, skin, hair (Kaufman, 2008)” are made up of these tissues. Protein acts to repair and maintain body tissues and cells. Therefore, intake of complete protein is particularly important to ensure that protein is sufficiently absorbed by the body. Recent studies show the health benefits of protein-rich diets to the heart. Lawrence Appel, together with the researchers of the John Hopkins University, said that “Overall, the protein-rich diet, derived from plant and animal sources, decreased cardiovascular disease risk by 21 percent.”
Meanwhile, according to Madelyn Fernstrom, protein is “necessary for maintaining the body’s normal growth and its muscle mass (which is mostly protein), its immune system, and heart and respiratory functions (2006).” Additionally, she says that the ideal amount of one’s daily protein intake should be 10 to a quarter percent of the calories you take per day.
One the one hand, excessive intake of proteins is safe as these are not stored in the body and are generally secreted. It can only be harmful if one has liver or kidneys diseases.
On the other hand, protein deficiency which usually stems from malnutrition can lead to death. As protein help build tissues and muscles in the body, protein deficiency can cause “muscle loss including heart muscles” (cited in Hansen et al 2000). Other cases that lead to protein deficiency are “under conditions of metabolic stress, such as infection, trauma, burns, AIDS and surgery (Nutrition Research, 2008).”
Basing from the information learned from various sources regarding complete proteins, it appears that such is essential for the human body to supply and optimize protein in the body. As it is important for the required daily allowance for protein is observed, complete protein containing all essential amino acids must be consumed.
However, one should not limit one’s source of protein from pork, beef or other animal meat. Fruits and vegetables, on right combinations can be complete proteins, and can also sufficiently supply daily needed protein. In essence, balance in food and nutrient absorption is still the key to good health.
Attwood, C. R. (1997).”Complete” proteins? Charles Attwood, M.D.Website. Retrieved March 18, 2008 from http://www.vegsource.com/attwood/complete_protein.htm.
Collier, C. (2008). Complete proteins. Fitness Together Website. Retrieved March 18, 2008 from http://ftchattanooga.com/complete_proteins.pdf.
Fernstrom, M. (2006). Protein 101: How much do you need?MSNBC Website. Retrieved March 18, 2008 from
Hansen R.D., Raja C., & Allen B.J.(2000) Total body protein in chronic diseases and in ageing. Annals of the New York Academy of Sciences, 904, 345–52.
Harvard School of Public Health (2007). Harvard School of Public Health Website. Protein: Moving closer to center. Retrieved March 18, 2008 from
Kaufman, J. (2008) Complete proteins. Fitness Together Website. Retrieved March 18, 2008 from http://ftchattanooga.com/complete_proteins.pdf.
Nutrition Research.(2008). Factsheet on protein. Northwestern University Website. Retrieved March 18, 2008 from http://www.feinberg.northwestern.edu/nutrition/factsheets/protein.pdf.