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hc8meifmdc|20005939267D|healthm_live|health_library|health_library_details|0xfdff5510090000001805000001000700
| Overview |
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The branched-chain amino acids (BCAAs) comprise the three essential amino acids L-leucine, L-isoleucine and L-valine. These amino acids are found in proteins of all life forms. Dietary sources of the branched-chain amino acids are principally derived from animal and vegetable proteins. Vegetables and juices contain small amounts of the free amino acids, which are also found in fermented foods like yogurt.
Although amino acids are generally not considered important energy sources, BCAAs serve as important fuel sources for skeletal muscle during periods of metabolic stress, such as during an intensive weight-training workout. Under such conditions, BCAAs may promote protein synthesis, suppress protein catabolism and serve as substrates for gluconeogenesis. BCAAs are mainly catabolized in skeletal muscle, stimulating the production of, among other substances, L-alanine and L-glutamine.
BCAA's are particularly important for weight training because they make up one third of muscle protein. BCAA's are essential for excessively stressed muscle to supply energy, promote healing and decrease recovery times, as well as preventing unwanted muscle tissue breakdown.
BCAA supplements have been proven in studies to increase muscle mass, lifting capacity, energy levels and immune function, while decreasing fatigue and muscle breakdown following intensive exercise. They are therefore shown to be of particular benefit to weight trainers, who need to push their muscles hard every session in order to build lean muscle mass, and cannot afford to wait forever for damaged tissue to regenerate.
The body requires a positive nitrogen balance to create an anabolic environment, which is optimal for muscle building. Positive nitrogen balance occurs when the amount of nitrogen entering a person's body is higher than the amount leaving it. Nitrogen cannot be obtained from carbohydrates or fats, only protein. So you must consume protein or amino acids in order to create a positive nitrogen balance. Branched chain amino acids are an excellent nitrogen source, in addition to their numerous other benefits.
Additionally, research has shown that increased amounts of amino acids in the bloodstream can increase the production of an anabolic hormone IGF-1, which stimulates cell growth and in particular muscle cells. This is an addition to the natural function of branched chain amino acids in preventing muscle tissue breakdown. They can even be used directly as an extra energy source in a pinch, so it is definitely a good idea to always maintain a high level of amino acids, including BCAAs if you are serious about maximizing the potential benefits of your weight training.
Professional bodybuilders find that taking amino acids before their workout helps them stay alert and focused throughout, and research suggests that this is because branched chain amino acids and the essential amino acid Tyrosine have been shown to manipulate neurotransmitter precursors with the result that the onset of fatigue is delayed. It is crucial to maintain focus during a workout in order to push your muscles hard and stimulate the transformation reaction that causes new lean muscle tissue to be synthesized.
BCAA supplements are usually supplied in capsule form for precise dosage, and the optimum time to take them is directly before, during and after a workout, when your body is most in need of the extra amino acids.
What is BCAA ?
BCAAs are a group of essential amino acids comprised of three essential amino acids. We have to memorize this famous trio as remembering to get these in sufficient amounts may do your body, mind and overall immunity a lot of good. The names of Branched-Chain Amino Acids are leucine, isoleucine and valine. All essential amino acids are needed to maintain a positive nitrogen balance. But when the three essential ones in focus, Leucine, Isoleucine and Valine, are combined together, they are used differently by the body.
Branched-Chain Amino Acids act as nitrogen carriers assisting the muscles in synthesizing other amino acids needed for building new cells and tissues. BCAA have been studied for their unique metabolism and ability to reduce or delay the onset of 'central fatigue', also known as fatigue of the Central Nervous System rather than the muscle.
As we may already know, before getting energy to our cells and tissues, any fuel needs to be oxidized, or combined with Oxygen. Physiologically, carbohydrates are the easiest ones to go down that road and form a great team with Oxygen giving us the needed spark to move and think. Proteins have some trouble dealing with Oxygen, but they can still manage after going through a long metabolic pathway known as Krebs cycle. All proteins first have to be broken down to amino acids in the intestine, absorbed through the tissues into blood, then travel to the liver which converts these to ketones, and only then amino acids may become useful for the body.
Branched Chain Amino Acids, the leucine, valine and isoleucine, can by-pass the liver stop and be used by the body as fuel in tissues other than the liver. Particularly, these are metabolized in the skeletal muscle tissue, so it makes sense that we use these more rapidly when we exercise.
The BCAA trio of isoleucine, leucine, and valine, are given the priority of oxidation.
BCAAs are not readily broken down by the liver. BCAAs in the muscle are able to transaminate Pyruvate to form amino acid Alanine, which is then recycled to glucose in the liver via the Cori cycle. If we really want to dig deep down the chemical reactions, we will try to simplify it as much as possible. BCAAs are broken down to their keto-acid analogues by very specific enzymes Branched-Chain Aminotransferase (BCAAT) and Branched-Chain oxo-acid dehydrogenase (BCOAD). Interestingly, the enzyme concentration increases with exercise. If at rest your body has only 5-8% of BCOAD available, during exercise this number goes up to 25%! What does this all mean? That during exercise you use more BCAAs than at rest.
Your brain governs how tired or energized, hungry or satisfied, rested or fatigued you feel. Essentially, several neurotransmitters in the brain, such as serotonin, GABA, dopamine, affect your sensations of mood, drive, pain, weariness and fatigue. Because the mechanism where the Branched Chain Amino Acids are involved is centered in the brain, BCAAs may help your entire system to go on for longer and delay fatigue. Remember a traffic jam near almost every business or shopping center during peak hours? For some reason, the road is empty at all other times, but when you need it the most, you wish that there were more lanes, right? Same thing with neurotransmitters. When you are at rest, happy and content, sitting on the couch in front of a TV set, all your neurotransmitters are in balance. But when the stress comes, the road by which these travel in your brain gets crowded.
Neurotransmitters are derived from amino acids. For example, amino acid tryptophan is a precursor to serotonin (5-hydroxytryptamine, or 5-HT), is known to depress the Central Nervous System and produce symptoms of fatigue. Research has shown that exercise reduces plasma BCAA levels while increasing the levels of tryptophan. This translates into a higher ratio of free tryptophan/BCAA. What does this all mean? Fatigue. More tryptophan means more serotonin. And when serotonin levels are up, you are down. But BCAAs may help turn the tables on fatigue and change the picture. Raising levels of BCAAs lowers the tryptophan/BCAA ratio bringing serotonin down and you don't even think about getting tired.
BCAAs also help maintain and repair muscles and tendons after exercise, injury, chronic illness, and even surgery because in combination, leucine, isoleucine and valine are involved in production of collagen and maintenance of connective tissue. They have shown to stimulate production of insulin, the main function of which is to allow circulating blood sugar to be taken up by the muscle cells and used as a source of energy.
Where it is found
Dairy and red meat are good sources of BCAA's, as well as whey, protein and eggs.
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Benefits / uses
Stimulate Protein Synthesis -- BCAAs by themselves have been shown to independently stimulate muscle protein synthesis. In other words, they have shown the ability to induce muscle gains, even in the absence of weight training! Studies have shown that BCAA supplementation increases the hormones: testosterone, growth hormone, and insulin. All of these are highly anabolic hormones. Research also shows that under conditions of extreme stress, such as hiking for 21 days at high altitude, BCAA supplementation (10 grams per day) was shown to increase muscle mass while subjects ingesting a placebo had no such change. The important thing here is these people gained muscle under extreme conditions without any anabolic stimulus such as weight training.
Stimulate Fat Loss -- Supplementation of BCAAs has been shown to trigger significant and preferential losses of visceral body fat. Located in the deeper layers of the body under the subcutaneous fat, this visceral fat tends to be resistant to dieting and is hard to lose. In one study, 25 competitive wrestlers were divided into 1 of 3 diet groups: a diet high in BCAAs, a diet low in BCAAs, and a control diet. The wrestlers stayed on the diets for 19 days. The results showed that the high BCAA group lost the most body fat, 17.3% on average. Much of the fat lost was in the abdominal region. This may give credence to BCAAs effectiveness at “spot reducing†the abs. In another study 2 groups of climbers were divided into a BCAA supplemented group and a control group. Both groups lost weight but the BCAA group actually gained muscle mass while losing fat and the other group lost muscle mass.
One theory as to how BCAAs exert their substantial fat burning and muscle building effects is this: When present in high amounts during exercise, the body senses high levels of BCAA in the bloodstream which is typically a sign of excessive muscle breakdown. So the body stops muscle breakdown and uses more fat for fuel. At the same time the extra BCAAs in the blood stimulate insulin so the BCAAs are driven directly to the muscle. So the result is people lose body fat and gain muscle at the same time. If my hunch is correct, in order to benefit the most from the fat loss aspect of BCAAs you should make sure you limit carbohydrate consumption during the 2 hour window before your workout.
Boosting Immune Function -- Remember if you're sick it's hard to train, much less grow. It's even harder to come back after an illness without losing a ton of strength and size. When you train at high intensity or high volume you risk immune suppression and infections. By supplementing with BCAAs you'll help reverse glutamine loss, which is essential for immune function. In addition to this, the BCAAs help prevent a catabolic state in the body, which in turn can help improve recovery and lessen the damaging effects your exercise sessions may have on the body.
Anti-Catabolic Effects -- BCAAs probably exert most of their anabolic effects through anti-catabolic activity. In short, they suppress the use of muscle proteins for fuel, thereby sparing the breakdown of muscular protein. In part this is because they can sacrifice themselves as fuel. With less muscular protein being broken down by the body during training, the net result is increased protein synthesis and more muscle for you! In a study done on obese people put on a starvation type diet, BCAA supplementation was found to induce anabolism and nitrogen sparing so the subjects burned body fat instead of lean muscle mass, thus sparing muscle protein.
Doses
BY MOUTH:
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For a brain condition due to liver disease (hepatic encephalopathy): 240 mg/kg/day up to 25 grams of branched-chain amino acids. |
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For mania: a 60 gram branched-chain amino acid drink containing valine, isoleucine, and leucine in a ratio of 3:3:4 every morning for 7 days. |
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For tardive dyskinesia: a branched-chain amino acid drink containing valine, isoleucine, and leucine at a dose of 222 mg/kg taken three times daily for 3 weeks. |
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For anorexia and improving overall nutrition in elderly malnourished hemodialysis patients: granules of branched-chain amino acids consisting of valine, leucine, and isoleucine at a dose of 4 grams taken three times daily. | |
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The estimated average requirement (EAR) of branched-chain amino acids is 68 mg/kg/day (leucine 34 mg, isoleucine 15 mg, valine 19 mg) for adults. However, some researchers think earlier testing methods may have underestimated this requirement and that the requirement is really about 144 mg/kg/day. Other researchers think the EARs for children are also low. EARs for branched-chain amino acids for children are: ages 7-12 months, 134 mg/kg/day; 1-3 years, 98 mg/kg/day; 4-8 years, 81 mg/kg/day; boys 9-13 years, 81 mg/kg/day; girls 9-13 years, 77 mg/kg/day; boys 14-18 years, 77 mg/kg/day; girls 14-18 years, 71 mg/kg/day.
INTRAVENOUS (IV):
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Healthcare providers give branched-chain amino acids intravenously (by IV) for brain enlargement due to liver disease (hepatic encephalopathy). | |
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Possible Side effects / Precautions / Possible Interactions:
Branched-chain amino acids appear to be safe for most people when used for up to 6 months. Some side effects are known to occur, such as fatigue and loss of coordination. Branched-chain amino acids should be used cautiously before or during activities where performance depends on motor coordination, such as driving.
Special Precautions & Warnings:
Pregnancy and breast-feeding: Not enough is known about the use of branched-chain amino acids during pregnancy and breast-feeding. Stay on the safe side and avoid use.
Amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease): The use of branched-chain amino acids has been linked with lung failure and higher death rates when used in patients with ALS. If you have ALS, don't use branched-chain amino acids until more is known.
Branched-chain ketoaciduria: Seizures and severe mental and physical retardation can result if intake of branched-chain amino acids is increased. Don't use branched-chain amino acids if you have this condition.
Chronic alcoholism: Dietary use of branched-chain amino acids in alcoholics has been associated with liver disease leading to brain damage (hepatic encephalopathy).
Low blood sugar in infants: Intake of one of the branched-chain amino acids, leucine, has been reported to lower blood sugar in infants with a condition called idiopathic hypoglycemia. This term means they have low blood sugar, but the cause is unknown. Some research suggests leucine causes the pancreas to release insulin, and this lowers blood sugar.
Surgery: Branched-chain amino acids might affect blood sugar levels, and this might interfere with blood sugar control during and after surgery. Stop using branched-chain amino acids at least 2 weeks before a scheduled surgery.
Interaction:
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Levodopa interacts with BRANCHED-CHAIN AMINO ACIDS
Branched-chain amino acids might decrease how much levodopa the body absorbs. By decreasing how much levodopa the body absorbs, branched-chain amino acids might decrease the effectiveness of levodopa. Do not take branched-chain amino acids and levodopa at the same time. |
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Medications for diabetes (Antidiabetes drugs) interacts with BRANCHED-CHAIN AMINO ACIDS
Branched-chain amino acids might decrease blood sugar. Diabetes medications are also used to lower blood sugar. Taking branched-chain amino acids along with diabetes medications might cause your blood sugar to go too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.
Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others |
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Diazoxide (Hyperstat, Proglycem) interacts with BRANCHED-CHAIN AMINO ACIDS
Branched-chain amino acids are used to help make proteins in the body. Taking Diazoxide along with branched-chain amino acids might decrease the effects of branched-chain amino acids on proteins. More information is needed about this interaction. |
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Medications for inflammation (Corticosteroids) interacts with BRANCHED-CHAIN AMINO ACIDS.
Branched-chain amino acids are used to help make proteins in the body. Taking drugs called glucocorticoids along with branched-chain amino acids might decrease the effects of branched-chain amino acids on proteins. More information is needed about this interaction. |
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Thyroid hormone interacts with BRANCHED-CHAIN AMINO ACIDS
Branched-chain amino acids help the body make proteins. Some thyroid hormone medications can decrease how fast the body breaks down branched-chain amino acids. However, more information is needed to know the significance of this interaction. | |
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| Research studies / References |
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Sowers, Strakie. "A Primer On Branched Chain Amino Acids". Huntington College of Health Sciences. http://www.hchs.edu/literature/BCAA.pdf. Retrieved 22 March 2011. |
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"Exercise Promotes BCAA Catabolism: Effects of BCAA Supplementation on Skeletal Muscle during Exercise". J. Nutr. 134 (6): 1583S-1587S. 2004. http://jn.nutrition.org/content/134/6/1583S.full. Retrieved 22 March 2011. |
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"Therapeutic use of branched-chain amino acids in burn, trauma, and sepsis". J. Nutr.. 1 Suppl 136 (30): 8S-13S. 2006. http://jn.nutrition.org/content/136/1/308S.short. Retrieved 22 March 2011. |
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"Nutrition in hepatic encephalopathy". Nutr Clin Pract. 25 (3): 257-64. 2010. doi:10.1177/0884533610368712. http://ncp.sagepub.com/content/25/3/257.abstract. |
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"Differential Metabolic Impact of Gastric Bypass Surgery Versus Dietary Intervention in Obese Diabetic Subjects Despite Identical Weight Loss". Sci Transl Med 3 (80re2). 2011. http://stm.sciencemag.org/content/3/80/80re2. Retrieved 27 April 2011. |
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"Mechanisms of human insulin resistance and thiazolidinedione-mediated insulin sensitization". Proc. Nat. Acad. Sci. USA 106 (44): 18745-18750. 2009. doi:10.1073/pnas.0903032106. http://www.pnas.org/content/106/44/18745.full. Retrieved 22 March 2011. | |
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