Branched-chain amino acids (BCAAs) are now one of the most popular supplements around, earning a place in millions of homes and gyms, worldwide. Numerous studies show a direct link between BCAA intake and improved strength and recovery, fuelling sales growth which shows no sign of slowing.
Whether you are a keen runner, professional tennis player, amateur weightlifter or an Olympic gold medallist, you could certainly benefit from adding more BCAAs to your diet.
Evidence supports the use of BCAA supplementation for strength and recovery during exercise but also recognizes their role in some diseases, such as cancer. Other studies have also linked bloodstream levels of BCAAs to insulin resistance and type-2 diabetes.
In this article, we’ll go over the main benefits of BCAAs for strength and recovery and why you should consider adding them to your diet.
Table of Contents
- What are BCAAs?
- Benefits of BCAAs
- Dangers, Side Effects & Toxicity
- Take Home Advice: Take BCAAs
What are BCAAs?
When we talk about protein, we are referring to amino acid residue – which is what protein is made from. BCAAs are essential amino acids because the body is unable to synthesize them on its own, therefore, they must be consumed in our diet. Of the nine essential amino acids, three of them fall into the BCAA category. They are:
- Leucine – boosts protein synthesis, helping build and repair muscle. It also assists with insulin to regulate blood sugars and is one of only two amino acids which cannot be converted into sugar.
- Isoleucine – enables energy to be stored in muscle cells rather than fat cells by regulating glucose uptake.
- Valine – improves mental functioning, reduces fatigue and prevents muscle breakdown.
Other essential amino acids are oxidized (broken down to release energy) in the liver, however, BCAAs are unique in that they can be metabolized in muscle. Why is this important? Well, the body needs BCAAs in the bloodstream to maintain normal bodily functions. If none are available, the body will break down muscle cells to release them.  
The supplement industry does a great job convincing us to invest in BCAA supplements to get optimal results. However, for the most part, you will get all you need from everyday foods.
The recommended intake of BCAAs is around 15-20 grams per day, so getting enough from your diet is not all that difficult. You should aim for around five grams per meal (assuming three square meals per day).
Here are some common foods with examples of their BCAA content, per 3oz serving, cooked.
- Cheddar Cheese – 4.7g
- Ground turkey – 4.2g
- Ground Beef (95% lean) – 4.0g
- Peanuts – 3.1g
- Cashew Nuts – 2.8g
- Whole eggs – 2.2g
- Chicken breast – 2.1g
- Lentils – 1.3g
- Black Beans – 1.3g
Lentils, black beans and kidney beans contain all three branched-chain amino acids; however, some plant-based foods are not “complete” proteins. For a food to be a complete protein source, it must contain all nine essential amino acids. While kidney beans and black beans are complete, lentils lack enough methionine.
You can overcome this problem by combining lentils with other foods high in methionine (such as rice) to form complete proteins. Peanuts suffer a similar problem because they lack the essential amino acid, lysine. To make it complete, simply spread it on bread or toast.
If you’re unsure what foods contain complete proteins, head over to nutritiondata.self.com. This fantastic site lists the protein and nutritional profiles of thousands of foods. If a protein is not complete, simply click the “find foods with complementary profile” link to find sources containing the missing essential amino acids.
The 2:1:1 Ratio
When you look at BCAA supplement packaging, you will nearly always find reference to the BCAA ratio. The most common is 2:1:1, made up of two-parts leucine, one-part isoleucine, and one-part valine. While 2:1:1 is the most common, you will sometimes see products with ratios of 4:1:1, 8:1:1 and even 10:1:1.
These higher ratio BCAA supplements all contain more leucine. If you take time to read the packaging or the manufacturer’s marketing materials, they usually reference the muscle-building power of leucine. In reality, they are just cheaper to produce, so you will rarely find them citing existing research to back up their claims.
Scientists have used the 2:1:1 ratio in studies based on the levels found in natural food sources. Historically, there has been little need to investigate other ratios. Nevertheless, the role of leucine in protein synthesis has caught some interest. While current evidence is limited, a ratio of 4:1:1 has shown promise in one study, where results found it to increase protein synthesis by over 30%.
Benefits of BCAAs
1. You’ll Build Major Muscle Mass
When looking to improve strength, or to build muscle (hypertrophy), you need to activate protein synthesis. For this to happen, leucine is the single most important dietary requirement. Chemical signals tell your body to build and repair muscle, and leucine effectively amplifies that signal – especially following resistance exercise. 
As leucine is the main amino associated with muscle growth, you might be wondering why this is not recommended as a standalone supplement for muscle growth. As it happens, studies have been conducted to investigate. One such study compared three groups: one took a placebo, the other a leucine supplement, while the third group consumed a regular BCAA drink with a ratio of 2:1:1. While leucine performed better than the placebo, it did not do as well as BCAA group.
The reason for this is simple: all amino acids are required for muscle growth. So, while leucine stimulates the process, other forms of protein are needed to build muscle. Without the other amino acids, leucine is like a motivational building site manager with no workers to do the job. 
2. You’ll Be Far Less Exhausted
Getting tired during a workout can be a real drag. You will be glad to hear that branched-chain amino acids – particularly valine – can help with this.
When you exercise, the level of tryptophan (another essential amino acid) rises. When tryptophan reaches the brain, it is used to make serotonin – a hormone been linked to our feeling of fatigue. All amino acids are transported to the brain on the same bus, yet not all are allowed entry to the brain. With limited accommodation available, valine competes with tryptophan and overpowers it. Less tryptophan in the brain means less serotonin, and less serotonin means lower fatigue. 
3. You’ll Recover Way Quicker
The body can take a real beating during intensive exercise. Recovering after such a session can take a few days or more.
One study, looking into the effects of BCAA supplementation in experienced resistance-trained athletes, showed positive results. The rate of recovery improved for strength, countermovement jump height and muscle soreness. BCAAs can also speed up recovery time following endurance sports and intensive cardio sessions.4. No More Muscle Catabolism
Our priority, when exercising – whether it’s to lose weight, tone up, or get healthier in general – is usually to improve our body composition; after all, better body composition makes you look more toned, and the health benefits are well documented.
While exercising, we need more BCAAs to function properly.  
When bloodstream levels are too low, the body looks for somewhere to get them. At this stage, it begins breaking down (catabolizing) muscle tissue to access the branched-chain amino acids it needs.
Consuming BCAAs ensures an adequate level is available in the bloodstream, reducing the chances of muscle breakdown. During and following intensive exercise sessions, it is important to consume slightly higher levels. This is the reason why some athletes will sip on a BCAA supplement drink during a workout.
Intermittent fasting has risen in popularity in recent years, with millions of people finding success with this form of dieting. As you can imagine, while in the fasted state, the bloodstream is low on BCAAs. Knocking back a very low-calorie BCAA drink during the fasted helps combat this.
Following a workout, a meal or meal replacement high in protein is typically consumed to further replenish BCAA levels. If the aim of the workout was to build muscle, this is the best time to give protein synthesis a boost with some muscle-building leucine. Fast acting carbs are also a good idea at this time, as the energy can be stored in the muscles as glycogen.
5. Massive Muscle Energy Storage
When you eat, the energy you consume is either used or stored. You could be forgiven for thinking that excess energy is stored in fat cells, but it’s not.
Once digested, carbohydrates are converted to glucose, which supplies your cells with energy. The hormone, insulin, helps regulate blood sugar. One of the ways it does this is by helping glucose move through cell walls to be stored.
Unused glucose is converted to glycogen and stored in the liver and muscle tissue. Any excess glucose which cannot be deposited as glycogen is finally stored in fat cells.
The fantastic thing about glycogen stored in muscle cells is this: once stored in the muscle, it cannot return to the bloodstream to be used anywhere else. It can be used only by the muscle. For this reason, encouraging glucose to be stored in muscle cells is preferable to it being stored as fat.
Glycogen stored in muscles is a readily available energy source. So, when blood sugars are too low, contracting muscles will use the fuel stored within them to get the job done. This is where the branched-chain amino acid, isoleucine, shines by promoting glucose uptake by muscles. Greater uptake means less energy is stored as fat resulting in quicker energy access for the muscle. 
Dangers, Side Effects & Toxicity
Is There a Risk of Toxicity
It is safe to say that consuming high levels of BCAAs is not toxic. Studies looked at toxicity in mice and rats, concluding there to be no observed-adverse-effect level. 
However, if you’re looking to maximize your training efforts, research shows that excessive levels of BCAAs can actually hinder performance. 
Inclusive Ties to Type-2 Diabetes
Maybe the largest concern for some people is that there is a direct link between high levels of BCAAs in the blood and type-2 diabetes.  On initial inspection, this looks to be bad news for branched-chain amino acids. However, further research suggests it is poor insulin sensitivity which drives higher circulating BCAA levels. 
Negative Effects on Insulin Sensitivity in Vegans
During a 2017 study, when supplementing with BCAAs, vegans became more resistant to insulin. 
During this study, they consumed an extra 20 grams of branched-chain amino acids per day for three months. Considering the lack of research on the subject, it is difficult to ascertain why this happened. Evidence shows that switching to a plant-based diet lowers the BCAA plasma levels associated with insulin resistance. 
The vegan subjects also had much better insulin sensitivity at the start of the study.
Increased Spread of Cancer & Disease
Inside our cells, a series of chemical reactions are constantly taking place. This series of events, known as a biological pathway, is what we refer to as our metabolism. These interactions produce new molecules such as fat or protein and can trigger changes in our cells.
The mTOR pathway forms part of this process. In simple terms, the mTOR pathway regulates cell growth. The branched-chain amino acid, leucine, stimulates the mTOR pathway, which is great for muscle growth, but not so great for some forms of cancer. Many cancers rely on mTOR activity for the growth and spread of cancerous cells. For this reason, much research is taking place regarding BCAAs and their link with diseases. 
Take Home Advice: Take BCAAs
It’s easy to see, given the evidence, why BCAAs are such a popular supplement for people engaging in exercise. Faster recovery, increased muscle growth, and reduced fatigue benefit all kinds of athletes, from beginners through to seasoned Olympians.
For those lifting weights, BCAAs will help you get bigger and stronger; marathon runners might delay hitting the wall, and if you’re playing competitive football week in week out, you can recover faster. In contrast, if you are not exercising regularly, there really is no need: just ensure you’re eating enough complete, plant-based proteins such as lentils, black beans, nuts and grains, some fish and meat a few times per week and you’ll be fine.
However, if you are vegan, your family has a history of diabetes, or have been recently diagnosed with a disease such as cancer, you should certainly consult with your doctor before adding BCAA supplements to your diet.
Featured photo credit: Brad Neathery via unsplash.com