Branched-Chain Amino Acids
Uses
The branched-chain amino acids (BCAAs) are leucine, isoleucine, and valine. BCAAs are considered essential amino acids because human beings cannot survive unless these amino acids are present in the diet.
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For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
3 StarsReliable and relatively consistent scientific data showing a substantial health benefit.
2 StarsContradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 StarFor an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
This supplement has been used in connection with the following health conditions:
| Used for | Why |
|---|---|
2 Stars Liver Cirrhosis At least 5 grams daily, up to 0.24 grams per 2.2 lbs (1 kg) body weight per day | Under a doctor’s supervision, supplementing with branched-chain amino acids may correct an imbalance of amino acids and improve cirrhosis symptoms. In addition to protein deficiency, liver cirrhosis is characterized by low blood levels of (BCAAs) in relation to other amino acids. This imbalance may contribute to the development of PSE. BCAA supplementation could be a way to correct this problem, as well as to provide a source of needed protein, but its effectiveness is unclear. BCAAs (isoleucine, leucine, and valine) represent a good protein source for people with cirrhosis because they are less likely to induce PSE. A controlled study of protein-intolerant people with cirrhosis showed that BCAA supplementation corrected abnormal protein metabolism about as well as an equivalent amount of dietary protein without inducing PSE as frequently. In a small double-blind trial, people with liver cirrhosis taking 5 grams per day of BCAAs had significant improvement in their ability to process protein. However, treatment trials using BCAAs alone or in solutions containing other amino acids in people with cirrhosis and PSE have reported conflicting results. It may be that certain people with liver cirrhosis can benefit from supplementation with BCAAs while others cannot, for reasons that are unclear. In a double-blind trial, people with liver cirrhosis and PSE received 0.24 grams per 2.2 pounds body weight (approximately 16–17 grams per day) of BCAAs for 15 days, after which most experienced significant improvement in brain function, mental status, and protein metabolism. Those who continued taking BCAAs for three months also had mild improvement in liver function tests. Therapeutic effects of oral BCAAs have also been shown in children with liver failure and in adults with cirrhosis of the liver without PSE. Overall, it appears that BCAA supplementation does not always help in cirrhosis, but some people with and without PSE may benefit. A qualified doctor must closely supervise such BCAA supplementation. |
2 Stars Phenylketonuria Take under medical supervision: 150 mg daily per 2.2 lbs (1 kg) of body weight each of valine and isoleucine, and 200 mg daily per 2.2 lbs (1 kg) of body weight of leucine | Regular use of branched-chain amino acids (BCAAs) may improve mental functioning. In a double-blind trial, regular use of (BCAAs) (i.e., valine, isoleucine, and leucine) by adolescents and young adults with PKU improved performance on some tests of mental functioning.Participants received either placebo, or 150 mg per 2.2 pounds of body weight each of valine and isoleucine, and 200 mg per 2.2 pounds of body of leucine, taken with meals and at bedtime. Participants received one mixture or the other for four three-month periods, for a total of six months’ supplementation of each regimen over the course of a year. |
1 Star Athletic Performance and Mental Decline During Exercise at Extreme Temperature Refer to label instructions | Some research has shown that branched-chain amino acids help prevent muscle loss at high altitudes, prolong endurance performance in the heat, and improve exercise-induced declines in mental functioning. Some research has shown that supplemental (BCAA) (typically 10 to 20 grams per day) do not result in meaningful changes in body composition, nor do they improve exercise performance or enhance the effects of physical training. However, BCAA supplementation may be useful in special situations, such as preventing muscle loss at high altitudes and prolonging endurance performance in the heat. One controlled study gave triathletes 6 grams per day of BCAA for one month before a competition, then 3 grams per day from the day of competition until a week following. Compared with a placebo, BCAA restored depleted glutamine stores and immune factors that occur in elite athletes, and led to a reported one-third fewer symptoms of infection during the period of supplementation. Studies by one group of researchers suggest that BCAA supplementation may also improve exercise-induced declines in some aspects of mental functioning. |
1 Star Athletic Performance and Post-Exercise Infection at Extreme Temperature Refer to label instructions | Some research has shown that branched-chain amino acids may support immune fuction and improve infection at high altitudes and prolong endurance performance in the heat. Some research has shown that supplemental (BCAA) (typically 10 to 20 grams per day) do not result in meaningful changes in body composition, nor do they improve exercise performance or enhance the effects of physical training. However, BCAA supplementation may be useful in special situations, such as preventing muscle loss at high altitudes and prolonging endurance performance in the heat. One controlled study gave triathletes 6 grams per day of BCAA for one month before a competition, then 3 grams per day from the day of competition until a week following. Compared with a placebo, BCAA restored depleted glutamine stores and immune factors that occur in elite athletes, and led to a reported one-third fewer symptoms of infection during the period of supplementation. Studies by one group of researchers suggest that BCAA supplementation may also improve exercise-induced declines in some aspects of mental functioning. |
1 Star Tardive Dyskinesia Refer to label instructions | Supplementing with branched-chain amino acids may reduce excess phenylalanine in people with tardive dyskinesia. Preliminary research has linked TD to the inability of the body to metabolize the amino acid phenylalanine. Supplementing with (BCAA), including valine, isoleucine, and leucine, could reduce excess phenylalanine in people with this disorder. In one trial, researchers examined the effects of BCAA supplementation in people with TD (from 150 mg per 2.2 pounds body weight, up to 209 mg per 2.2 pounds body weight) after breakfast and one hour before lunch and dinner for two weeks. The BCAA mixture included equal parts valine and isoleucine plus 33% more leucine than either of the other two amino acids. Of nine people treated, six experienced at least a 58% reduction in symptoms, and all nine had a least a 38% decrease. |
How to Use It
Most diets provide an adequate amount of BCAAs for most people, which is about 25–65 mg per 2.2 pounds of body weight.1, 2 Athletes involved in intense training often take 5 grams of leucine, 4 grams of valine, and 2 grams of isoleucine per day to prevent muscle loss and increase muscle gain, though most research does not support this use of BCAAs.
Where to Find It
Dairy products and red meat contain the greatest amounts of BCAAs, although they are present in all protein-containing foods. Whey protein and egg protein supplements are other sources of BCAAs. BCAA supplements provide the amino acids leucine, isoleucine, and valine.
Possible Deficiencies
Only a person deficient in protein would become deficient in BCAAs, because most foods that are sources of protein supply BCAAs. Few people in Western societies are protein deficient.
Interactions with Supplements, Foods, & Other Compounds
Interactions with Medicines
Side Effects
Side effects have not been reported with the use of BCAAs. Until more research is conducted, people with ALS should avoid taking supplemental BCAAs. In one study, supplementation with a large amount of BCAAs (60 grams) caused alterations in the blood levels of tryptophan, phenylalanine, and tyrosine.3 The changes in the blood levels of these amino acids could, in theory, cause depression in susceptible individuals. Until more is known, individuals with a history of depression should consult a doctor before supplementing with BCAAs. People with kidney or liver disease should not consume high amounts of amino acids without consulting their doctor.
1. Zello GA, Wykes LF, Ball RO, et al. Recent advances in methods of assessing dietary amino acid requirements for adult humans. J Nutr 1995;125:2907-15.
2. Young VR, Bier DM, Pellett PL. A theoretical basis for increasing current estimates of the amino acid requirements in adult man, with experimental support. Am J Clin Nutr 1989;50:80-92.
3. Scarna A, Gijsman HJ, Harmer CJ, et al. Effect of branch chain amino acids supplemented with tryptophan on tyrosine availability and plasma prolactin. Psychopharmacology 2002;159:222-3.
Last Review: 06-01-2015
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