Fundamentals of Human Nutrition/Dietary intake

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5.5 Dietary Intake:PROTEINEdit

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5.5.1 ExcessEdit

The recommended dietary allowance (RDA) for an average person is 0.8g/kg, but some groups may need a higher amount (such as children, women during pregnancy and lactation, or athletes). An upper level has been set at 30% of the total calorie intake. [1]

There are three main risks associated with high protein diets: dehydration, kidney damage and bone damage.

- Dehydration occurs by the need to excrete large amounts of urea and other nitrogenous wastes from protein catabolism. It can be prevented by increasing fluid consumption. [1]

- Kidney damage has been proved in people with prior renal problems. Kidneys would not be able to eliminate all the waste products of protein metabolism. However, no studies have shown significant proof of this link in healthy individuals. [1] [2]

- Bone damage has been a controversial topic over the last years. Some studies claim catabolic effect and others claim anabolic effect. Those that claim catabolic effect (lose of bone density) blame the acids generated by the oxidation of aminoacids. These acids would destabilize the acid-base balance. In order to excrete the excess acid load, the bone will release calcium, magnesium and other compounds to serve as the buffers. Studies claiming anabolic effect point at the intake of fruits, vegetables and dietary calcium to balance out the excess of acid. [1] [3-7]


[1] Sareen Grooper, Jack Smith (2009). Advanced Nutrition and Human Metabolism.

[2] William Martin, Lawrence Armstrong and Nancy Rodriguez (2005). Dietary protein intake and renal function. Retrieved from

[3] Uriel Barzel, Linda Massey (1998). Excess dietary protein can adversely affect bone. Retrieved from

[4] Robert Heaney (1998). Excess dietary protein may not adversely affect bone. Retrieved from

[5] Bess Dawson-Hughes (2003). Interaction of dietary calcium and protein in bone health in humans. Retrieved from

[6] Robert Heany and Donald Layman (2008). Amount and type of protein influences bone health. Retrieved from

[7] Robert McLean et al. (2011). Dietary acid load is not associated with lower bone mineral density except in older men. Retrieved from

5.5.2 DeficiencyEdit

In the United States, protein deficiencies are not as common as protein excess is. This is because almost all of our food has a significant amount of protein in it. Protein-rich foods provide us with essential amino acids that are needed for daily function. Foods that supply us with essential amino acids include, but are not limited to, meat, dairy products, and eggs. (Tuso, Ismail, Ha, Bartolotto, 2013)

Essential amino acids also come from various combinations of plant-based foods such as quinoa. (Tuso, Ismail, Ha, Bartolotto, 2013) While protein deficiency is not a rampant issue within the United States, it can be detrimental for those who suffer from it. Those who suffer from protein deficiencies are unable to perform daily tasks properly and suffer from many harmful symptoms.

Here are different types of protein deficiencies according to Protein Deficiencies Diseases:

  • Protein S deficiency
  • Protein C deficiency
  • Marasmus
  • Kwashiorkor
  • Protein S and C deficiencies are not a result of malnutrition but are instead inherited disorders. (Chen, 2014) In contrast to this, marasmus and kwashiorkor are both results of extreme malnourishment and deficiencies of protein.

Protein S and CEdit

People who are deficient in protein S and C are lacking the proteins that are present in the fluid of the blood. Protein S and C deficiencies are rare congenital disorders that cause abnormal blood clotting. (Chen, 2014) Protein C deficiencies are more common than protein S deficiencies and affect 1 out of 300 people. (Chen, 2014) Protein S deficiencies are found in every 1 out of 20,000 people – making it a much more rare deficiency. (Chen, 2014) These deficiencies make themselves present and are “characterized by pain, redness, swelling, and tenderness in the affected areas.” (Protein Deficiencies Diseases) Complications as a result of these deficiencies may occur as childhood strokes, recurring miscarriages, recurrent clots in veins, and pulmonary embolism. (Chen, 2014) It is crucial for people who suffer from these protein deficiencies to avoid activities that can cause blood clotting or seek professional help by potentially going on a blood thinner.


Marasmus is a devastating and common deficiency seen in young, malnourished children. Marasmus is the “most common form of acute malnutrition in nutritional emergencies” and it can often lead to fatality. (Types of Undernutrition) Young children and infants who suffer from this deficiency try to conserve energy by reducing physical activity and their bodies reduce growth. (Types of Undernutrition) Because these children are not getting the nutrients or protein that they need, their bodies’ organs will begin to limit their function, which puts the children at extreme risk.


Malnourishment can also take on the form of extreme bloating and stomach swelling which is known as kwashiorkor. The swollen stomach is a result of fluid retention within the individual. (“Med-Health”) This form of malnourishment comes from a lack of proteins from carbohydrate sources and is more common in older children. (“Med-Health”) Clinical signs of kwashiorkor include (Types of Undernutrition):

  • Loss of appetite
  • Apathy and irritability
  • Changes in hair color
  • Dermatosis

Chen, Yi-Bin. "Congenital Protein C or S Deficiency: MedlinePlus Medical Encyclopedia." U.S National Library of Medicine. U.S. National Library of Medicine, 26 Nov. 2014. Web. 02 Nov. 2015. (Links to an external site.)

Tuso, Philip J., Mohamed H. Ismail, Benjamin P. Ha, and Carole Bartolotto. "Nutritional Update for Physicians: Plant-Based Diets." The Permanente Journal. The Permanente Journal, n.d. Web. 02 Nov. 2015. (Links to an external site.)

"" Protein Deficiency Diseases. N.p., n.d. Web. 02 Nov. 2015. (Links to an external site.)

"Clinical Forms of Acute Malnutrition." Types of Undernutrition: Growth Failure -. UNICEF, n.d. Web. 02 Nov. 2015. (Links to an external site.)