Finding the right training supplements is a challenge. And digging through shelves and shelves hoping to find ones that actually work is a whole other story.

But there are two supplements in particular that, when used correctly, offer a whole slew of benefits in terms of muscle growth, strength, endurance, and performance.

They’re two of the most common and commended fitness add-ins, and while both technically amino acids, they have two unique roles during training.

So, when it comes to choosing between beta-alanine and BCAA, it’s not about which one is better, but rather which one will work to achieve your needs. Maybe one, maybe both.

Let’s explore the ins and outs of beta-alanine and BCAAs, so you can determine which one is best for you.

What Is Beta-Alanine?

Beta-alanine is a non-essential beta-amino acid that occurs naturally within the body, but is also widely found in animal foods as well as supplements.

Unlike the other 20 amino acids, the amino group in beta-amino acids is bonded to the β-carbon rather than the α-carbon, giving it a slightly different function within the body.

Rather than being used towards muscle protein synthesis, beta-alanine joins with L-histidine to produce carnosine, which is stored in skeletal muscle and acts as an intramuscular buffer to maintain proper pH 1.

What Does It Do?

Before we get into the role of beta-alanine in exercise, it’s first important to understand what happens in muscles when you’re training.

Glucose is the primary energy substrate used to fuel muscles during intense exercise. The breakdown of glucose in muscles creates lactate and a buildup of hydrogen ions (H+).

This buildup causes the pH of muscles to increase, forming lactic acid. As lactic acid accumulates, it increases the acidity of muscle tissues to a point where muscles lose their ability to contract, which results in subsequent loss of endurance and power.

Intramuscular acidosis is one of the leading causes of fatigue during intense exercise. But carnosine is shown to play a significant role in muscle pH regulation; carnosine is synthesized in skeletal muscle from the amino acids L-histidine and β-alanine.

As such, the rate-limiting factor of carnosine synthesis is the availability of β-alanine 1. So, to prevent hitting a point where carnosine synthesis stops, you supplement with beta-alanine, which ultimately increases muscle carnosine content and, therefore, total muscle buffering capacity.

Studies on the effects of beta-alanine supplementation on exercise performance have found significant improvements in performance during multiple bouts of high-intensity exercise, as well as single bouts of exercise lasting over 60 seconds 1.

And while it may not improve maximal strength or VO2max, it has shown a positive result on specific aspects of endurance performance, such as anaerobic threshold and time to exhaustion.

One specific study tested three different beta-alanine doses: 40, 20, and 10 mg/kg of body weight 2. The highest dose elicited a peak in serum beta-alanine levels in 60 minutes, but also the most intense and unpleasant symptoms of paresthesia.

They suggested that the maximum tolerable single dose of beta-alanine may be around 800mg. However, symptoms of paresthesia are transient and solely related to the increase in plasma concentration.

CarnoSyn®, the patented beta-alanine present in Performance Lab Pre, is one of the most effective beta-alanine supplements that buffers hydrogen by increasing muscle levels of carnosine, which enables muscles to contract for a longer period and delay the onset of fatigue 3.

What are BCAAs?

The BCAAs, or branched-chain amino acids, comprise three essential amino acids that play a foundational role in muscle protein synthesis (MPS). Leucine, isoleucine, and valine are considered to be the building blocks of functional proteins.

Because the body can’t manufacture them endogenously, they have to be obtained through dietary protein or amino acid supplementation.

What Do They Do?

BCAA supplements are a staple in an athlete’s and bodybuilder’s supplement repertoire, largely because of their role in MPS but also to reduce fatigue onset and improve exercise performance.

The human body can utilize BCAAs as a fuel source during workouts when glycogen stores are depleted, but the prominent role of the BCAAs is to augment training adaptations.

Because muscle tissue repair requires the presence of all 20 amino acids, 9 of which are essential, supplying your body with the three most prominent muscle-building amino acids helps to kickstart that process. And of those nine amino acids, leucine plays a significant role in muscle protein synthesis.

However, it’s important to keep in mind that MPS stimulation can be achieved by supplying the essential amino acids (EAAs) only, but when you’re just supplementing with the three BCAAs, you forget about the other six required for muscle building.

But some studies suggest that only a few amino acids may be key regulators in MPS rather than a combination of them all 4.

The branched-chain amino acid, leucine, plays a unique role in stimulating MPS because it serves as a substrate for the synthesis of new muscle proteins and as a signal to initiate the rate-limiting translation initiation step of MPS 4.

Stimulation of MPS is accompanied by increased activity of intracellular signaling proteins regulating the translational activity of MPS 5. Specifically, the mammalian target of rapamycin complex-1 (mTORC1) signaling is stimulated by the ingestion of essential amino acids following resistance exercise.

Basically, if you’re looking to maximize your opportunity for muscle growth, supplementing with BCAAs ensures there is substrate available to stimulate it.

But there’s another important role for BCAAs. Like beta-alanine, BCAAs are a promising supplement for reducing fatigue onset because of their role in offsetting 5-HT (serotonin) levels in the brain.

Changes in 5-HT concentration are a mechanism suggested as a potential cause of fatigue during workouts.

Because tryptophan crosses the blood-brain barrier during exercise and is the precursor for serotonin synthesis, higher serotonin levels during exercise signal to the brain that your body is fatigued, which translates directly into reduced endurance capacity and reduced strength.

However, the transport of 5-HT is influenced by tryptophan availability concerning other amino acids because all amino acids compete for the same transport proteins to cross the blood-brain barrier.

Because larger amino acids typically win the battle to get on the transport protein compared to smaller amino acids like tryptophan, the BCAAs help to displace tryptophan from entering the brain, thus reducing conversion to serotonin and delaying the onset of fatigue 6.

That means that supplementing with BCAAs before or during your workout enables less transport of tryptophan, less serotonin synthesis, greater muscular endurance, and less fatigue.

What To Take: Beta-Alanine or BCAAs

Like we said before, it’s not a “one or the other” game when it comes to BCAAs and beta-alanine. They both help to improve muscular endurance and performance, but they both have different mechanisms of doing so.

Since changes in 5-HT concentrations are only one mechanism associated with muscle fatigue, pairing BCAAs and beta-alanine can make a big difference in endurance performance and help fight muscle fatigue.

And because beta-alanine buffers lactic acid threshold in working muscles, they both come together to inhibit fatigue and maximize overall athletic performance.

Thus, it’s not about which one is better; it’s more about where to find the best supplements. 

Final Thoughts

When you have two equally beneficial supplements, it’s hard to choose one of the other. But in this case, you don’t have to. BCAAs and beta-alanine are two of the most commended fitness supplements, and they both offer a different set of strengths.

Despite both improving muscular endurance and training volume, the difference is in how they do so. Beta-alanine buffers the buildup of lactic acid, while BCAAs alter levels of 5-hydroxytryptamine (5-HT) that has been suggested as a potential factor in the onset of fatigue.

So, if you want to minimize your potential for fatigue and maximize your workout capacity, you should probably invest in both, not just one.


  1. GG Artioli, B Gualano, A Smith, J Stout, AH Lancha Jr. Role of beta-alanine supplementation on muscle carnosine and exercise performance. Med Sci Sports Exerc. 2010;42(6):1162-1173.
  2. RC Harris, MJ Tallon, M Dunnett, et al. The absorption of orally supplied A-alanine and its effect on muscle carnosine synthesis in human vastus lateralis. Amino Acids. 2006;30(3):279–89.
  3. ET Trexler, AE Smith-Ryan, JR Stout, et al. International society of sports nutrition position stand: Beta-Alanine. J Int Soc Sports Nutr. 2015;12:30. Published 2015 Jul 15.
  4. SJ Crozier, SR Kimball, SW Emmert, JC Anthony, LS Jefferson. Oral leucine administration stimulates protein synthesis in rat skeletal muscle. J. Nutr. 2005;135: 376–382.
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