Amino Acids in Human Body

by Jeffrey Traister

About Jeffrey Traister

Jeffrey Traister is a writer and filmmaker. For more than 25 years, he has covered nutrition and medicine for health-care companies and publishers, also producing digital video for websites, DVDs and commercials. Trained in digital filmmaking at The New School, Traister also holds a Master of Science in human nutrition and medicine from the Columbia University College of Physicians and Surgeons.


Amino acids are perhaps best known as the building blocks of protein. Your body contains several amino acids, and, while many of these amino acids work together for protein synthesis, some amino acids have other roles in your body. You need to consume amino acids every day from food because your body does not store these nutrients. Consult your doctor about your amino acid requirements.

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Humans require 20 different amino acids to make protein, and nine of them -- the essential amino acids -- must be obtained through food. That's because you can't produce them on your own. The essential amino acids include leucine, isoleucine, valine, tryptophan, phenylalanine, histidine, lysine, methionine and threonine. The other 11 non-essential amino acids that you can produce include alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine.

Branched-Chain Amino Acids

Leucine, isoleucine and valine are called branched-chain amino acids and play a significant role in building and sustaining lean muscle mass. Consuming branched-chain amino acids before heavy weightlifting and other bodybuilding exercises can help you increase your lean muscle mass and reduce muscle soreness and fatigue after your workout. Research done by scientists at the Nagoya Institute of Technology in Nagoya, Japan, and published in the "Journal of Nutrition" in 2006 indicated that supplementing your diet with branched-chain amino acids prior to squat exercises decreases muscle soreness and muscle fatigue that might normally occur for a few days following exercise. The research concludes that branched-chain amino acids might be useful for muscle recovery after exercise.

Neurotransmitter Precursors

Some amino acids also help you make neurotransmitters -- chemicals needed for brain function. The amino acid L-tryptophan helps you make serotonin, a neurotransmitter that regulates appetite, sleep and mood. L-tyrosine aids in producing norepinephrine, an excitatory neurotransmitter that also affects mood and behavior. Eating a carbohydrate meal can increase your blood concentrations of tryptophan and tyrosine relative to other amino acids, enabling these two amino acids to enter your brain to synthesize serotonin and norepinephrine, according to research by scientists at Massachusetts Institute of Technology in Cambridge and published in the "American Journal of Clinical Nutrition" in 2003.


Any food that contains protein provides you with amino acids. Some foods -- including dairy, eggs, meat, soy and quinoa -- are complete proteins, and provide each of the 9 essential amino acids. Other foods -- including most other plant-based foods -- provide some of the amino acids you need from your diet. However, combining plant-based foods allows you to consume all the amino acids you need for good health. Pair rice with beans, whole-grain toast with peanut butter, or hummus with a whole-wheat pita to get the amino acids you need.

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This article reflects the views of the writer and does not necessarily reflect the views of Jillian Michaels or