Editing Essential amino acid (section)

==Effects of deficiency==
{{Main|Protein-energy malnutrition}}
If one of the essential amino acids is not available in the required quantities, protein synthesis will be inhibited, irrespective of the availability of the other amino acids.<ref name="DRI" /> Protein deficiency has been shown to affect all of the body's organs and many of its systems, for example affecting brain development in infants and young children; inhibiting upkeep of the immune system, increasing risk of infection; affecting gut [[mucosal]] function and permeability, thereby reducing absorption and increasing vulnerability to [[systemic disease]]; and impacting kidney function.<ref name="DRI" /> The physical signs of protein deficiency include [[edema]], [[failure to thrive]] in infants and children, poor musculature, dull skin, and thin and fragile hair. Biochemical changes reflecting protein deficiency include low [[serum albumin]] and low [[serum transferrin]].<ref name="DRI" />

The amino acids that are essential in the human diet were established in a series of experiments led by [[William Cumming Rose]]. The experiments involved elemental diets to healthy male graduate students. These diets consisted of [[corn starch]], [[sucrose]], [[butterfat]] without protein, [[corn oil]], inorganic salts, the known [[vitamin]]s, a large brown "candy" made of liver extract flavored with [[peppermint oil]] (to supply any unknown vitamins), and mixtures of highly purified individual amino acids. The main outcome measure was [[nitrogen balance]]. Rose noted that the symptoms of nervousness, exhaustion, and dizziness were encountered to a greater or lesser extent whenever human subjects were deprived of an essential amino acid.<ref name=RoseIsoleucine>{{Cite journal |last1=Rose |first1=WC |last2=Haines |first2=WJ |last3=Warner |first3=DT |title=The amino acid requirements of man. III. The role of isoleucine; additional evidence concerning histidine |journal=J Biol Chem |year=1951 |volume=193 |issue=2 |pages=605–612 |doi=10.1016/S0021-9258(18)50916-9 |url=http://www.jbc.org/content/193/2/605.full.pdf |archive-url=https://web.archive.org/web/20160615233640/http://www.jbc.org/content/193/2/605.full.pdf |archive-date=2016-06-15 |url-status=live |access-date=15 December 2012 |pmid=14907749|doi-access=free }}</ref>

Essential amino [[acid]] deficiency should be distinguished from [[protein-energy malnutrition]], which can manifest as [[marasmus]] or [[kwashiorkor]]. [[Kwashiorkor]] was once attributed to pure protein deficiency in individuals who were consuming enough [[calorie]]s ("sugar baby syndrome"). However, this theory has been challenged by the finding that there is no difference in the diets of children developing [[marasmus]] as opposed to kwashiorkor.<ref>{{cite journal |vauthors=Ahmed T, Rahman S, Cravioto A |title=Oedematous malnutrition |journal=The Indian Journal of Medical Research |volume=130 |issue=5 |pages=651–4 |pmid=20090122 |year=2009}}</ref> Still, for instance in [[Dietary Reference Intake]]s (DRI) maintained by the [[USDA]], lack of one or more of the essential amino acids is described as [[protein-energy malnutrition]].<ref name="DRI" />