The reason branched chain amino acids (BCAAs) are a major concern for bodybuilders is because these important building blocks make up a third of muscle protein and have many different functions to assist the bulky breed in their lifetime quest to lift more, grow bigger muscles and get as strong as possible. The interest in branched chain amino acids has a valid foundation because they are extremely important for protein metabolism and overall body support.
There is evidence that taking BCAAs orally seems to reduce muscle breakdown during exercise, increase protein synthesis, regulate blood sugar levels and aid in fat loss. Additionally, BCAAs have been studied for their potential role in delaying central nervous system (CNS) fatigue, especially in athletes. Particularly important for all bodybuilders, BCAAs’ anabolic properties are ranked very high. And it is not just healthy and physically active people who thrive on BCAAs. Clinically, branched chain amino acids are used to treat depression, diabetes, anorexia, irritability and headaches that result from protein deficiency.
So, what is so special about BCAAs? Aren’t all amino acids the same? Not at all! Even though all amino acids are important for the simple fact of their paramount involvement in cellular metabolism, the mechanism by which these work is much more complex.
BCAAs are a group of essential amino acids that are composed of three main amino acids. It’s important to remember this famous trio because these three are crucial for your body, mind and overall immunity. The names of these three branched chain amino acids are leucine, isoleucine and valine. All essential amino acids are needed to maintain a positive nitrogen balance. But when these three essential BCAAs are combined together, they are used differently by the body.
Besides building cells and repairing tissue, proteins form antibodies to combat invading bacteria and viruses. They also comprise the enzyme and hormonal systems, build nucleoproteins (RNA & DNA), carry oxygen throughout the body, and are part of all metabolic processes in the body. But the body cannot directly use proteins found in food and must break these down into smaller units, known as amino acids. Out of 22 amino acids required for proper bodily functioning and optimal health, your body can make 10-12 in sufficient amounts from glucose and other proteins. These are called non-essential amino acids and include alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine, and tryptophan.
The rest of them need to be supplied through your diet since your body is not designed to make them, hence the name “essential amino acids”. These include tryptophan, lysine, methionine, phenylalanine, threonine, valine, leucine, and isoleucine. Their function is to serve as nitrogen donors to make other amino acids and supply the most important structural material for the new cells to develop and replace the old ones.
Semi-essential amino acids are arginine and histidine. The need for these increases if they get depleted during times of stress. Adults can usually make enough of these to maintain normal balance, just like nonessential amino acids. However, growing bodies and tissues may require more of these and treat them as essential. For example, bodies of certain individuals go through additional stress of having to construct more new cells than average. Bodybuilders, athletes, children, those injured, ill, and even the elderly need additional amounts of amino acids to support muscle tissue growth due to higher metabolic demands.
Individually, leucine is used to synthesize enkephalins, natural painkillers similar to endorphins. Furthermore, leucine can be an important source of calories, and is superior as fuel to dextrose, an easily digestible form of sugar. Leucine also stimulates insulin release, stimulating protein synthesis and inhibits protein breakdown.
Isoleucine promotes muscle recovery, regulates blood sugar levels, stimulates growth hormone release, plays a role in wound healing, assists in the formation of hemoglobin and is strongly involved in the formation of blood clots.
Valine produces energy when your body is under severe stress, such as trauma, surgery, liver failure, infection, fever, starvation and when doing resistance training like weight lifting. Similar to the rest of BCAAs, valine is metabolized mainly by muscles and is involved in their preservation and construction.
BCAAs Unique Metabolism – Pushing the Energy Buttons
Branched chain amino acids act as nitrogen carriers assisting the muscles in synthesizing other amino acids needed for building new cells and tissues. If this sounds pretty much the same as for other amino acids, it’s important to understand that BCAAs 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 you may already know, before getting energy to your cells and tissues, any fuel needs to be oxidized, or combined with oxygen. Physiologically, carbohydrates are the easiest to go down that road and form a great team with oxygen which gives you the needed spark to move your body and think. Proteins have some trouble dealing with oxygen, but they can still manage after going through a long metabolic pathway known as the Krebs Cycle. All proteins fist have to be broken down into amino acids in the intestine, absorbed through the tissues into blood, then travel to the liver which converts these to ketones, and only then can amino acids become useful for the body.
What is extremely exciting is that branched chain amino acids (leucine, valine, isoleucine) can bypass the liver 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 you use these more rapidly when you exercise.
More than that, BCAAs are the first amino acids to be oxidized (used for energy), which is not a very typical action of amino acids and proteins. Given the conditions, your muscles can oxidize with at least these amino acids: alanine, asparagine, aspartate, glutamate, isoleucine, leucine, lysine and valine. But during exercise, the BCAA trio of isoleucine, leucine, and valine, are given the priority of oxidation.
Following ingestion, BCAAs are not readily broken down by the liver. BCAAs in the muscle are able to transfer pyruvate to form the amino acid alanine, which is then recycled to glucose in the liver via the Cori cycle. If you really want to dig deep down the chemical reactions, I 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. At rest, your body has only 5-8% of BCOAD available, but during exercise this number goes up to 25%! What does this all mean? During exercise you use way more BCAAs than at rest. This is the same for all other amino acids. But the BCAAs are used directly by the muscles, and oxidation is one of the things you need to think about if you doubt the fact that proteins are not the best source of energy (which is true, by the way).
Let’s get back to the point of the specific benefits of branched chain amino acids. If you haven’t forgotten by now, these structural protein components help offset fatigue triggered by exercise. Here is why. BCAAs are not metabolized in the liver like the rest of the nutrients, but they instead circulate and compete for absorption into the blood-brain barrier with the amino acids tryptophan, tyrosine, phenylalanine, and methionine for access to the neural amino acid transport system which allows amino acid entry to the brain.
Your brain governs how tired or energized, hungry or satisfied, rested or fatigued you feel during the day. 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 longer and delay fatigue. It’s like a traffic jam near almost every business or shopping centers 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 to your brain gets crowded.
Neurotransmitters are derived from amino acids. For example, the amino acid tryptophan is a precursor to serotonin (5-hydroxytryptamine, or 5-HT) which 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? The result is fatigue!
More tryptophan means more serotonin and when serotonin levels are up, you are down (fatigued, tired, dizzy). 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. Some researchers speculate that supplementing with BCAAs will lower this ratio and result in improved mental and physical performance.
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 the production of collagen and maintenance of connective tissues. They have shown to stimulate the 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. In other words, the insulin production induced by BCAAs helps muscle cells to take up other amino acids and use these for constructive purposes.
It is recommended to take 5 grams of leucine, 2.5 grams of isoleucine, and 4-5 grams of valine on an empty stomach twice daily (in the morning and before workouts). As a rule of thumb, a 2-1-2 equilibrium in Leucine, Iso-leucine, Valine dosing yields the best results.
Safety of BCAAs
There are mixed reviews regarding the safety of taking BCAA orally. It is probably safe when used appropriately and short term. Side effects include an increase in plasma and muscle accumulation of ammonia, which itself can contribute to fatigue, temporary loss of motor coordination and compromised muscle and brain function. Dietary use of BCAAs in alcoholics has also been associated with hepatic encephalopathy.