Leucine is a branched-chain amino acid (BCAA) that is critical for muscle repair and protein synthesis.
In fact, leucine may be considered the most important of the three BCAAs.
The other two branched-chain amino acids are valine and isoleucine. Leucines’ importance is due to it being the primary amino acid involved in the building of muscle tissue.
As an amino acid, Leucine is one of the “building blocks” of protein and muscle tissue.
As you consume protein your body breaks it down into amino acids. Those amino acids help build muscle and help the body function properly.
It has been noted in studies that leucine helps wounds heal, regulates blood sugar levels, and produces growth hormones.
Leucine is one of the nine essential amino acids that the body needs to grow and function properly.
Unlike nonessential amino acids, essential amino acids cannot be created by the body. Therefore, the essential amino acids need to be digested through foods or supplements.
The greatest natural sources of leucine through the diet are animal proteins such as poultry, eggs, and meat.
Leucine can also be ingested through other sources such as beans and legumes.
In supplements you will see “L-Leucine” and “Leucine” as ingredients. These two terms refer to the same active ingredient.
Leucine has many potential benefits, but most studies are centered around its effects on muscle growth and athletic performance.
Leucine Uses
There are many potential uses for leucine supplements, some of which are more proven than others.
Some of these potential benefits include:
* Strength performance: In one study, researchers had participants supplement with 4 grams of leucine each day during a 12-week resistance training program. This documented study showed that L-leucine supplementation resulted in a significant increase in strength performance. Leucine may be used as a nutritional supplement to enhance strength performance – either on its own or combined with other BCAAs.
* Muscle recovery: A study where participants supplemented before doing squats suggest that leucine may be useful for muscle recovery following exercise. Ultimately, leucine strongly promotes protein synthesis in skeletal muscles, and protein synthesis is vital for proper post-workout recovery.
* Muscle loss: In a two week study the researchers supplemented meals of older adults with 4 grams of leucine per meal, three times a day. Researchers in this study found leucine supplementation may improve muscle protein synthesis in response to lower protein meals in older adults. This may be beneficial for slowing muscle loss in older populations, but more research is needed.
* Muscle gain: It is thought that leucine supplementation may be beneficial for muscle growth, when combined with strength training. Results have shown that low levels of leucine signals mechanistic Target of Rapamycin (mTor) to be disabled. When leucine levels reach sufficient levels, mTor is increased and muscle building can begin.
There are more claimed benefits of leucine supplementation, but they may not have adequate clinical evidence supporting them.
As a whole, leucine supplements need more clinical research in order to fully realize its potential benefits.
It’s also worth noting that there are many documented benefits of branched chain amino acids, as BCAAs in general are very well-studied.
There have been fewer studies looking specifically at Leucine by itself.
How to Take Leucine
Leucine is known to be bitter tasting as a powder, so you may want to consider capsules if you cannot stomach bitter tastes.
If you want to consume the powder, it can be mixed with protein shakes, smoothies, etc.
There are also flavored powders available, which help to mask the bitter taste of leucine.
There is not an established daily dose for leucine, but most studies above consisted of 4,000 – 5,000 mg per day.
Examine.com notes that leucine is typically supplemented in the 2,000 – 5,000 mg per day range.
Depending on your personal goals, manufacturers recommend taking leucine before and after workouts. It may also be beneficial to take before bed to help recovery during sleep.
Side Effects and Precautions
There are no known harmful side effects for taking branched-chain amino acid (BCAA) supplements such as Leucine.
There may be some potential interactions with pharmaceuticals, however.
For instance, leucine supplements combined with diabetic medications can drop blood sugar levels. Therefore, patients with hypoglycemia should not take leucine supplements.
Be sure to ask your doctor or physician before taking supplements. That way, your doctor can check to see if there are any side effects or interactions with medications or foods.
Leucine supplements should not be used by infants, or women who are pregnant or breastfeeding.