Aid Overall Health / Improve Sports / Increase Energy

L-isoleucine is a common ingredient found in quite a few bodybuilding supplements. It is one of several amino acids used in such supplements to help bodybuilders build muscle mass, strength, and endurance.

It's also included because it has some known properties which help bodybuilders recover faster after strenuous workouts. In most cases, manufactures use L-isoleucine use as part of a proprietary blend. Therefore, it's difficult to say just how much of the substance is in any given product.

L-isoleucine is known scientifically as an essential amino acid. Being classified as "essential" simply means that it is required by the human body but cannot be synthesized from other sources.  It must be directly ingested through foods we eat such as eggs, soy protein, cheese, poultry, and fish. One of the benefits of this amino acid is that while our bodies don't normally produce it, they can store it in large quantities for later use.

Most of us get enough of this amino acid from our normal diets. But for bodybuilders and other athletes involved in strenuous activity, specific diets or supplementation is needed. Without it, the body's catabolic functions kick in, converting molecules in muscle tissue to energy rather than building that muscle tissue. This property of L-isoleucine means it's also categorized as a ketogenic amino acid. 

Not all types of physical activity are suitable for everyone. Users take training advice at their own personal risk.


L-isoleucine Benefits In addition to being a ketogenic amino acid L-isoleucine is also classified as glucogenic. This means that it is functionally necessary to help produce glucose from non-carbohydrate substances in the body. Without this glucogenic synthesis, glucose levels in the blood... more

L-isoleucine Benefits

In addition to being a ketogenic amino acid L-isoleucine is also classified as glucogenic. This means that it is functionally necessary to help produce glucose from non-carbohydrate substances in the body. Without this glucogenic synthesis, glucose levels in the blood would fall to dangerously low levels. This is of special concern during periods of strenuous exercise where energy sources are being used up much more quickly than normal.

According to some in the industry L-isoleucine is most effective as a supplement in terms of boosting energy and increasing endurance. This makes sense when you consider that the synthesis of glucose from non-carbohydrates would accomplish both of those things. That said, there's no clear understanding of how much L-isoleucine is needed before it results in a measurable benefit. It is known that a lack of this amino acid can result in a condition known as hypoglycemia, among other things.

Lastly, researchers and industry experts believe L-isoleucine helps to promote the rebuilding and repair of muscle tissue in the hours immediately after a workout. However, L-isoleucine's catabolic properties mean that it should work in just the opposite way. Nonetheless, supplement makers stand by it as an affective amino acid for muscle rebuilding.

L-isoleucine Side Effects

Because L-isoleucine is an essential amino acid the body normally needs to function properly, it is assumed to be safe in moderate consumption by healthy people. There are no reports of side effects listed in any medical journals or supplement industry papers. This supplement is not regulated by the FDA.

That said, there are certain types of people who should always be cautious when ingesting any amino acid supplements. Those include people suffering from liver and kidney diseases. Excess amino acids could pose significant problems to individuals suffering from these conditions.

Because a proper balance of amino acids in the body is a delicate thing, supplement makers also caution users to follow dosage instructions right down to the letter. In the case of L-isoleucine, it needs to be taken in combination with several other amino acids in order for it to work properly without throwing off the balance of other amino acids. This may be one of the reasons why manufactures include it as part of a proprietary blend rather than as a standalone supplement. These blands might very well contain the right balance of all the amino acids together.

L-isoleucine and Other Uses

L-isoleucine is extensively used in the medical community for the treatment of several conditions, not the least of which is diabetes. Because of its glucogenic properties this amino acid does a great job in regulating blood sugars. Diabetics who use the supplement regularly are usually better able to manage their blood sugar. The substance is also believed to promote at least a minimal production of additional insulin. In combination with dietary restrictions L-isoleucine can be very helpful.

Despite the fact that excess of amino acids can be harmful to those suffering from liver and kidney diseases, it is believed by doctors that proper amounts of L-isoleucine may be good under certain conditions because it helps promote liver protein synthesis. However, only a doctor can determine how much of the substance is suitable for an individual patient.

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  • Side Effects
  • Other Names
  • Uses
Acides Aminés à Chaîne Ramifiée, Aminoacidos Con Cadenas Laterales Ramificadas, BCAA, BCAAs, Branched Chain Amino Acid Therapy, Branched Chain Amino Acids, Isoleucine, Isoleucine Ethyl Ester HCl, Leucine, Leucine Ethyl Ester HCl, Leucine Isovaleric Acid, Leucine Methyl Ester HCl, L-Isoleucine, L-Leucine, L-Leucine Pyroglutamate, L-Valine, N-Acetyl Leucine, Valine, 2-amino-3-methylvaleric acid, 2-amino-4-methylvaleric acid, 2-amino-3-methylbutanoic acid
Blood Sugar Regulation
Increased Endurance
Increased Energy
Muscle Recovery
Muscle Repair