Branched Chain Amino Acids (BCAA)
(BCAA)

General Info

Active Forms
Isoleucine, leucine, and valine.

Absorption
BCAAs are absorbed from the intestinal tract. However, the mucosal cells of the small intestine also metabolize BCAAs for the synthesis of other proteins and amino acids in the intestinal tract.

Dietary Sources
Branched chain amino acids are most commonly found in protein foods from animals.

Dosage Info

Dosage Range Branched chain amino acid products vary widely in their composition, ranging from 200-300mg of each BCAA daily to 2-5 grams of each daily. Most Common Dosage 150mg of each daily. Dosage Forms Tablets, capsules, and powders.		Adult RDI None established Adult ODA None established		RDA None established

Overview

Interactions

Nutrient/Nutrient Interactions
•	phenylalanine
•	tryptophan
•	tyrosine

The BCAAs make up approximately one-third of muscle protein and are important for building and maintaining muscles. The BCAAs have been called the “stress amino acids” because muscles have a greater need for these amino acids during times of physical stress and intense exercise. The primary market for BCAA supplements are body builders and other athletes undergoing intense exercise. There is little indication that additional intake of these amino acids produce significant results in healthy individuals. Some studies have reported that the branched-chain amino acids are effective in the treatment of liver disease,(1) and to help restore muscle mass in patients who have undergone surgery or trauma.

Toxicities & Precautions

BCAAs are absorbed from the intestinal tract. However, the mucosal cells of the small intestine also metabolize BCAAs for the synthesis of other proteins and amino acids in the intestinal tract.

General
There is no known toxicity associated with branched chain amino acids.

BCAAs compete with the aromatic amino acids for entry into the brain. Therefore, people ingesting large doses of BCAAs should be advised that this might result in a decline of brain levels of serotonin and dopamine.(2)

Functions in the Body

Uses

Clinical Applications
	Alcoholic Liver Damage
	Amyotrophic Lateral Sclerosis (ALS)
	Catabolic Stress
	Intense Exercise
	Surgery

Energy:
Metabolism takes place primarily in muscle tissue; the BCAAs can be directly used by skeletal muscles as a source of energy.(3, 4)

Protein Synthesis:
Primary function of the BCAAs is the anabolic role they play in facilitating the synthesis of proteins in the body.

Clinical Applications

Alcoholic Liver Damage
Alcoholics with advanced liver disease have been found to have a deficiency of BCAAs.(5)

Amyotrophic Lateral Sclerosis (ALS)
During a 1-year trial, ALS patients treated with BCAAs exhibited a significant benefit in terms of maintenance of muscle strength and continued ability to walk whereas the condition of control patients continued to decline.(6)

Catabolic Stress
BCAAs facilitate protein synthesis, and they are required in larger amounts than other amino acids during stress. Supplemental BCAAs have therapeutic value in conditions such as trauma, extreme physical stress, renal failure, and burns.(7)

Intense Exercise
BCAA supplementation prior to exercise reportedly helps prevent muscle protein breakdown and improves recovery after periods of intense workouts.(8) In another study, two groups of athletes were tested with either BCAA supplements or a placebo during high altitude trekking. Athletes taking the BCAA supplement had less loss of body mass, greater decrease in fat mass, and greater increase in lean body mass (+1.5 percent vs no change in placebos). Arm muscle mass increased in the BCAA group, whereas the placebo group had a 6.8 percent decrease, and lower limb power decreased less in the BCAA group (-2.4 percent) compared to the placebo group (-7.8 percent).(9)

Surgery
Malnourished surgical patients are frequently given BCAAs as part of intravenous parenteral nutrition. Some physicians report that patients who are treated with BCAAs both pre- and postoperatively recover from surgery more quickly than those not treated.(10)

Symptoms & Causes of Deficiency

A deficiency of valine reportedly causes neurological problems. Individuals with a deficiency of isoleucine develop muscle twitching and tremors. There are no published studies reporting symptoms associated with leucine deficiency. Protein/calorie starvation for a period longer than one week, a condition known as kwashiokor, causes BCAA levels to become deficient.

Footnotes

¹ Poon RT, Yu WC, Fan ST, Wong J. Long-term oral branched chain amino acids in patients undergoing chemoembolization for hepatocellular carcinoma: a randomized trial. Aliment Pharmacol Ther. Apr2004;19(7):779-88.
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² Lucca A, et al. Neutral Amino Acid Availability in Two Major Psychiatric Disorders. Prog Neuropsychopharmacol Biol Psychiatryu. Jul1995;19(4):615-26.
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³ De Lorenzo A, Petroni ML, Masala S, et al. Effect of acute and chronic branched-chain amino acids on energy metabolism and muscle performance. Diabetes Nutr Metab. Oct2003;16(5-6):291-7.
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⁴ Karlsson HK, Nilsson PA, Nilsson J, Chibalin AV, Zierath JR, Blomstrand E. Branched-chain amino acids increase p70S6k phosphorylation in human skeletal muscle after resistance exercise. Am J Physiol Endocrinol Metab. Jul2004;287(1):E1-7.
View Abstract
⁵ Bernardini P, et al. Amino Acid Imbalance and Hepatic Encephalopathy. Annu Rev Nutr. 1982;2:419-54.
⁶ Plaitakis A, et al. Pilot Trial of Branched-chain Aminoacids in Amyotrophic Lateral Sclerosis. Lancet. May1988; 1(8593):1015-18.
View Abstract
⁷ Sax HC, et al. Clinical Use of Branched-chain Amino Acids in Liver Disease, Sepsis, Trauma, and Burns. Arch Surg. Mar1986;121(3):358-66.
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⁸ Carli G, et al. Changes in the Exercise-induced Hormone Response to Branched Chain Amino Acid Administration. European Journal of Applied Physiology. 1992;64:272-77.
View Abstract
⁹ Schena F, et al. Branched-Chain Amino Acid Supplementation During Trekking at High Altitude. European Journal of Applied Physiology. 1992;65:394-98.
View Abstract
¹⁰ Braverman ER. The Healing Nutrients Within. New Canaan, CT: Keats Publishing, Inc. 1997;339.

Branched Chain Amino Acids (BCAA)(BCAA)

Branched Chain Amino Acids (BCAA)
(BCAA)