October 17th, 2018
leucine valine isoleucine

The BCAA Leucine: Benefits, Uses and Side Effects

BCAA supplements are incredibly popular. They deliver great muscular energy, help build muscle and help expedite your recovery from a hard workout. If you’ve ever taken a one of these supplements, you’ve experienced the benefits of leucine, one of three branched chain amino acids that make up the active ingredients of BCAA products.

What is it?

Leucine is one of three branched chain amino acids. Often on BCAA supplement labels, you see a ratio such as “2:1:1″ or “3:1:1″. This indicates the ratio of the three BCAAs in that product: leucine, isoleucine, and valine.

It is an essential amino acid and must therefore be ingested, as it is not naturally synthesized in our bodies. It can be found naturally in most dietary protein sources.


By stimulating protein synthesis in muscles, leucine supplementation helps promote muscle growth (hypertrophy).

It also helps reduce and prevent muscle damaged by resistance training. decrease your recovery time caused by delayed onset muscle soreness (DOMS), which is why it is such a popular product for weightlifters.

How it works

You workout hard and are sore the next day. Resistance training and other forms of exercise increase the rate of protein degradation and tissue damage in your muscles. A side effect of this is a negative protein balance in your muscles and muscle soreness.

Here comes leucine.

In your body, you have what is called the mammalian target of rapamycin (mTOR), which is a protein synthesis regulator. mTOR helps regulate cell growth, proliferation, survival, protein synthesis and transcription.

Post workout, your serum levels of protein, specifically leucine are down. These low levels cause mTOR to deactivate because essentially there is not enough protein in your system to synthesize skeletal muscle protein and muscle growth.

However, when leucine concentrations are positive, mTOR is activated and the anabolic process to build new skeletal muscle begins (hypertrophy).

Therefore, by having higher concentrations available, your body recovers faster and skeletal muscle growth (hypertrophy) is stimulated.

How to Use It/Dosage

Most studies show that around 16mg of Leucine per kilogram of bodyweight is adequate, while others show that up to 45mg per kilogram of bodyweight is necessary for those participating in high intensity exercise. Most BCAA featured products have anywhere from 1,500mg to 4000mg of leucine.

It is recommended to take leucine in combination with the other two BCAAs isoleucine and valine. As leucine has the highest potential to stimulate muscle growth and recovery, most BCAA/recovery/protein products contain a 2:1:1 leucine to isoleucine to valine ratio or higher.

Potential Side Effects

Taken in moderation, there are limited side effects. However, in high dosages, potential side effects can be hypoglycemia, ammonia accumulation and pellagra.

As with all nutritional supplementation, we recommend consulting with a physician before taking any products.


Leucine is an amazing supplement. It has great benefits and can really help weightlifters achieve their goals quicker.

However, is it necessary to take extra through a BCAA supplement? It depends on your goals and cash flow. Often times, protein supplements and natural sources of protein that you eat have high levels of leucine. This means if you get enough protein in your diet through food or protein shakes, it may not be necessary to supplement a BCAA product.

Evan Clark

Evan Clark is a former wildland firefighter turned fitness pro (NSCA CPT). Though he loves his heavy squat and deadlift sessions, he believes that health and fitness extend well beyond the gym and that fitness should be a tool to promote mental health and lifestyle balance.

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