Branched-chain amino acids (BCAAs) and protein are popular supplements. While BCAAs and proteins are relatively similar to each other from a macronutrient point of view, there are subtle differences between the two supplements.
The primary purpose of supplementary protein and BCAAs is to provide the body with building blocks (amino acids) upon which muscle can be repaired and developed. While supplementary protein is made up of almost all amino acids, supplementary BCAAs only contain the amino acids that are primarily used for muscle growth (leucine, isoleucine, and valine).
What is Protein?
Protein is one of the major macronutrients, along with carbohydrates and fats. As a macronutrient, it provides the body with energy in the form of calories. Protein provides the body with the building blocks to create the thousands of different proteins and enzymes that the body needs to function properly.
Protein is a complex structure composed of simple building blocks; These are called amino acids. There are twenty different amino acids and while the body can naturally produce 11 of these (called nonessential amino acids), the other nine can only be obtained through diet (called essential amino acids).
The nonessential amino acids include alanine, arginine, asparagine, aspartic acid, cystine, glutamic acid, glycine, ornithine, proline, serine, and tyrosine. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.
Protein can be naturally found in foods such as meat, fish, legumes, and dairy. However, different food sources can have different quality proteins. These qualities can be in the form of amino acid availability, absorption, and bioavailability.
In fitness, supplementary protein is typically in the form of whey protein. Whey is one of the proteins in milk (the other being casein) and it is a byproduct of the cheese-making process as it is the liquid that remains after straining curdled milk.
Whey is an excellent protein source as it is a complete protein, or a protein source that contains all essential amino acids. Compared to food sources that are incomplete proteins because they only contain some of the essential amino acids.
Aside from containing all of the essential amino acids, whey also has among the highest bioavailability and digestibility making it extremely readily available for the body to utilize.
Benefits of Protein Supplements
As mentioned, protein can naturally be found in the diet, but there have been numerous benefits associated with protein supplements.
A review paper published in 2015 in the Journal of Food Science briefly summarizes the benefits of supplemental protein and high-protein diets in general. These benefits include (1) promoting muscle gain, (2) sparing muscle loss during weight loss, (3) slowing down muscle loss that comes with aging.
In terms of muscle growth, a 2014 paper published in the Scandinavian Journal of Medicine and Science in Sports compared the muscle growth (in terms of cross-sectional area of the quadriceps and the patellar tendon) between volunteers subjected to a protein supplement treatment and a carbohydrate placebo. Accompanied with resistance training, the study lasted for 12 weeks and concluded that resistance training with protein supplements increased muscular growth.
For sparing muscle loss in weight loss, a 2008 paper published in Nutrition and Metabolism showed researchers conduct an experiment where obese people were given a whey-protein supplement in addition to their diets. The study found that the treatment group and the control group lost relatively the same amount of weight. However, the treatment group tended to lose more body fat and retain more lean muscle. This study shows that protein supplements can encourage the body to retain muscle while losing fat in weight loss regimens.
Lastly, protein supplementation has also been studied to battle sarcopenia – age-related decrease in muscle mass and performance. A 2019 paper published in Aging and Disease neatly summarizes how whey protein and resistance training can prevent and treat sarcopenia. Protein supplements and resistance training have been shown time and time again to induce muscle protein synthesis in mammals and have also been studied to do so in the elderly.
What are BCAAs?
As their name suggests, BCAAs are amino acids classified due to their chemical structure. There are only three amino acids that are considered to be BCAAs: leucine, isoleucine, and valine.
In terms of promoting muscle mass gain, leucine is very important. Leucine acts as a signal that plays a role in protein synthesis. Muscle protein synthesis is a product of numerous enzymes signaling one another in an enzymatic cascade with leucine as one of the integral activators.
Benefits of BCAAs
There is no reason to believe that BCAAs will not confer the same benefits as stated for protein supplements since BCAAs are simply amino acids themselves. Especially since the three BCAAs have been observed to make up a significant portion of muscle proteins – up to 35%. However, BCAAs can provide a specific set of advantages.
Unlike most amino acids, these three BCAAs have been observed to break down in the skeletal muscles, and not in the liver. This is catalyzed by the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex. This phenomenon leads scientists to believe that these BCAAs are possibly involved in energy production in the muscles.
BCAAs also aid in regulating blood sugar levels in the body. These branched-chain amino acids encourage the skeletal muscles to utilize glucose from the blood instead of utilizing carbohydrate reserves in the muscles and the liver in the form of glycogen. This phenomenon is primarily attributed to isoleucine and valine. Meanwhile, leucine is more associated with muscle protein synthesis. This is why BCAAs often come in 2:1:1 ratios (leucine:isoleucine:valine).
Furthermore, supplementary BCAAs are being investigated as treatments for various medical ailments such as hyperammonemic states (liver cirrhosis and urea cycle disorders), traumatic brain injury, heart diseases (ischaemic heart disease and myocardial infarction), and hepatic encephalopathy.
BCAA vs Protein
There are only a handful of differences between BCAAs and protein that an individual has to consider when choosing between the two supplements.
The first difference a person can see is the supplement form. Supplementary protein typically comes in powdered form. This form is intended to be mixed with water or juice and should be consumed within the day.
However, BCAAs are already concentrated and are simply composed of the three amino acids so their form differs. These supplements typically come in the form of capsules/pills as well as powders.
Second, the price value of BCAAs and protein supplements differ. BCAAs are relatively more difficult to synthesize and manufacture and as a result, they cost more; BCAAs can cost almost twice the amount of protein powder. While $20 can be used to get a kilogram of protein powder, the same amount of money can also be used for only around 500 grams of BCAAs.
Deciding between BCAAs and protein highly depends on the fitness goal of the individual. For most people, protein should be more than enough as it is cheaper and already contains all the amino acids that the body needs. BCAAs are ideal for people with calorie-restricted diets because they will be consuming the amino acids necessary for muscle growth without any additional calories that can be typically found in protein supplements.