Branch chain amino acids, or BCAA’s for short, are claimed to stimulate muscle protein synthesis, help with recovery, and provide energy during a workout. BCAA’s are probably one of the most popular supplements in the fitness industry, but are they all that they claim to be?
What Are BCAA’s?
There are 20 amino acids, 9 of which are essential in adults - meaning the body can’t make them and they must be obtained through the diet. All amino acids have similar characteristics in their molecular structure but don’t worry, I’ll spare you the boring details. Valine, Leucine, and Isoleucine contain a chain of one central carbon atom attached to three or more carbon atoms - hence the name branch chain amino acids.
To build a protein, single units of amino acids join to form polymers that include dipeptides, tripeptides, oligopeptides, polypeptides, and proteins. When you eat protein, it is eventually broken down into small polypeptides and free amino acids. These free amino acids can be absorbed through a number of different transporters by intestinal cells and multiple amino acids can be absorbed by the same transporter.
Muscle Protein Synthesis
When you exercise, there is muscle protein breakdown occurring. In order for muscle growth/repair to occur, muscle protein synthesis must exceed muscle protein breakdown. It is thought that taking BCAA’s stimulates muscle protein synthesis. Consuming high amounts of competing amino acids can lead to decreased absorption rates. Amino acids that use the same carrier compete for absorption and this results in impaired or imbalanced absorption. This implies that supplementing with BCAA’s will result in fewer amino acids being absorbed which means a decrease in muscle protein synthesis - the exact opposite of what you’re taking the supplement for! Valine, Leucine, and Isoleucine are 3 of the 9 essential amino acids and these 3 alone do not appear to increase muscle protein synthesis; all of the essential amino acids must be present if not all 20 amino acids. Also of interest, is the fact that absorption of peptides obtained from digestion is more rapid than absorption of an equivalent mixture of free amino acids aka BCAA supplements. There is actually some evidence that BCAA’s negatively affect muscle protein synthesis. It’s not looking too good for BCAA’s.
Energy During A Workout
Do BCAA’s help reduce fatigue? It is postulated that BCAA’s decrease serotonin release by competitively inhibiting tryptophan (one of the 9 essential amino acids) transport into the brain. Serotonin is correlated with sleepiness and fatigue. Tryptophan and BCAA’s use the same transporter at the blood brain barrier so by taking a BCAA supplement, you are affecting tryptophan transportation efficacy which would mean serotonin levels decrease which would mean decreased fatigue. Unfortunately, there are no studies to back this hypothesis. In fact, there is evidence to show the contrary. Not only do BCAA’s diminish tryptophan uptake, but they diminish tyrosine uptake as well. Tyrosine is a precursor to the chatecholamine neurotransmitters dopamine and norepinephrine. Chatecholamines are very important to exercise as they regulate fuel sources, muscle contraction, blood pressure, and more. Once again, it’s not looking good for BCAA’s.
A case FOR supplementation: Although BCAA’s seem utterly useless, people who follow a vegan/plant-based diet and the elderly may benefit from BCAA’s. Plant-based protein has an inferior amino acid profile compared to animal sources, so supplementing with BCAA’s may help fill out the incomplete profile. Comparing the older population to the younger population, muscle protein synthesis does not increase to the same degree when exposed to the same protein dose. If you are 60 or older, you may benefit from BCAA’s. My final case in support of BCAA’s is the fact that they may help your water intake. BCAA’s come in many different flavours and can help those who struggle to take in appropriate amounts of water; but this is a really expensive way of increasing your water intake.
BOTTOM LINE: don’t waste your money! The majority of the population that are gym rats are already consuming enough protein with plenty of BCAA’s already and their gainz will be just fine. With the current research findings, you’re better off spending your money at the grocery store than the supplement store.
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