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Protein / Amino acid review

Nine Essential amino acids

Essential amino acids cannot be synthesized by the body and therefore it is 'essential' to include them in  the diet.

histidine,  leucine,  isoleucine,  lysine, methionine, phenylalanine, threonine,  tryptophan,  valine.

histidine leucine isoleucine lysinemethionine
phenyalaninethreoninetryptophanvaline

Estimated daily requirements for an adult based on the World Health Organization (WHO) guidelines:

Amino acid mg/kilogram 70 kg adult
Histidine 10 700 mg
Isoleucine 20 1400 mg
Leucine 39 2730 mg
Lysine 30 2100 mg
Methionine + Cysteine 10.4 + 4.1 (15 mg/kg total) 1050 mg
Phenylalanine + Tyrosine 25 mg/kg total 1750 mg
Threonine 15 1050 mg
Tryptophan 4 280 mg
Valine 26 1820 mg

Non-essential amino acids

Generally, these amino acids are considered non-essential because they can be synthesized from other amino acids.
 
alanine,
asparagine,
aspartic acid,
glutamic acid,
Selenocysteine

alanine asparagine aspartic acid  glutamic acid selenocysteine

Conditional  amino acids

Conditionally essential amino acids are usually not required in the diet, however, some individuals do not synthesize some of these amino acids in sufficient amounts and therefore must be included in the diet.  An example would be a patient with phenylketonuria who must drastically restrict phenylalanine intake in order to prevent severe metabolic disturbances.  The reduction in the available phenylalanine causes a profound reduction in tyrosine production which is normally synthesized by  the conversion of phenylalanine. Therefore tyrosine becomes an essential amino acid.

arginine,
cysteine,
glutamine,
glycine,
proline,
serine,
tyrosine



arginine cysteine glutamineglycineproline
serinetyrosine

Note: glycine is the simplest amino acid. Note its basic structure.....
Special cases - Sulfur-containing amino acids
Sulfur-containing amino acids
cysteine methionine
Special cases - Aromatic amino acids
Aromatic amino acids - Each of these amino acids contain a ring structure.

phenyalanine    tyrosine tryptophan
Special cases - Branched Chain Amino Acids

Branched-chain Amino Acids:
leucine,
isoleucine and
valine


isoleucine    leucine valine

The branched chain amino acids (BCAA) are all essential.   Each BCAA has a bulky nonpolar aliphatic side chain (open-chain hydrocarbon - carbon atom bound to more than two other carbon atoms).

Other:

  • The branched-chain amino acids are the most common essential amino acids.
  • BCAA's are metabolized mainly in skeletal muscle unlike the other 17 amino acids. Other amino acids must first pass through the liver before they are available to muscle tissue.
  • All three BCAA follow the same catalytic pathway initially: BCAA aminotransferase > Branched-chain ketoacid dehydrogenase > and acyl CoA dehydrogenase.
  • Protein powders that contain higher concentrations of branched-chain amino acids have a much higher bioavailability.
  • The BCAA's are thought to be highly beneficial for athletes because they help to increase carbohydrate bioavailability in the muscles and help prevent muscle protein breakdown during rigorous exercise.
  •  Branched-chain amino acids may reduce fatigue in both anaerobic and endurance sports
  • BCAA's account  for ~35% of the essential amino acids in muscle proteins.
Daily requirements
Amino acid mg/kilogram 70 kg adult
Histidine 10 700 mg
Isoleucine 20 1400 mg
Leucine 39 2730 mg
Lysine 30 2100 mg
Methionine + Cysteine 10.4 + 4.1 (15 mg/kg total) 1050 mg
Phenylalanine + Tyrosine 25 mg/kg total 1750 mg
Threonine 15 1050 mg
Tryptophan 4 280 mg
Valine 26 1820 mg

Disclaimer

The authors make no claims of the accuracy of the information contained herein; and these suggested doses are not a substitute for clinical judgment. Neither GlobalRPh Inc. nor any other party involved in the preparation of this program shall be liable for any special, consequential, or exemplary damages resulting in whole or part from any user's use of or reliance upon this material.PLEASE READ THE DISCLAIMER CAREFULLY BEFORE ACCESSING OR USING THIS SITE. BY ACCESSING OR USING THIS SITE, YOU AGREE TO BE BOUND BY THE TERMS AND CONDITIONS SET FORTH IN THE DISCLAIMER.   Read the disclaimer
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