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L-isoleucine is an essential branched-chain amino acid (BCAA), which aids the production of protein in the body.

What are its health benefits?

L-isoleucine is one of three proteinogenic amino acids, the others being L-leucine and L-valine. The body does not produce these essential amino acids, so we have to obtain them from dietary or supplement sources.

Because BCAAs assist in protein production in the body, they may reduce muscle breakdown associated with certain conditions. They also appear to prevent faulty message transmission in the brain cells related to certain conditions.

L-isoleucine taken in supplement form with L-leucine and L-valine may have the following benefits:

  • There is evidence to suggest that taking BCAAs assists in the improvement of liver and brain function in patients with a liver disease and those diagnosed with poor brain function.
  • Taken in liquid form, BCAAs seem to provide relief of symptoms associated with mania (a mental illness).
  • Provides relief of symptoms of tardive dyskinesia, a movement disorder.
  • Improves appetite in anorexia patients, and in elderly kidney-failure and cancer patients.
  • Assists in reducing muscle and protein breakdown during exercise, and aid muscle repair afterwards.
  • Used to assist in the management in slowing down muscle wasting in bed-bound individuals.
  • Used to help prevent fatigue and improve concentration.

Do you have a deficiency?

BCAAs are essential components of the human body, and are particularly involved in muscle and energy metabolism. A deficiency may result in weakness, dizziness, neurological and memory problems, and even depression. An L-isoleucine deficiency particularly may cause muscle tremors.

Find it in these food sources

BCAAs are found in the following food sources:

  • Meat: beef, pork, chicken, turkey
  • Dairy products: milk and cheese
  • Eggs
  • Nuts and seeds: peanuts, almonds and sunflower seeds
  • Legumes
  • Grains: wheat germ, oats, corn and rice

Recommended dietary allowance (RDA)

It is recommended that the three branched chain amino acids are taken together as a supplement, and are usually to be found in this format as a unit, where the ratios of each BCAA are worked out.

The dosage depends on the condition being treated. Speak to your Clicks pharmacist or doctor for guidance on dosage.


There is not enough information on the safe use of BCAAs during pregnancy or breastfeeding, so it’s best to avoid taking them.

BCAAs may affect blood sugar levels, which could interfere with blood sugar control during surgery, it is advised to stop using them two weeks before a scheduled surgery.

Do not use L-isoleucine if you have been diagnosed with one of the following conditions:

  • Amyotropic lateral sclerosis (ALS) or Lou Gehrig’s disease
  • Branched-chain ketoaciduria
  • Chronic alcoholism
  • Idiopathic hypoglycaemia in children

Avoid when taking the following medication:

Possible side effects

Side effects could include:

  • Electrolyte imbalance
  • A build-up of the amino acid in the bloodstream can potentially lead to branched chain ketoaciduria (maple syrup urine disease)

Ensure you discuss dietary supplementation with your Clicks pharmacist to avoid the potential for side effects and adverse interactions with medications.

This medicine has not been evaluated by the Medicines Control Council. This medicine is not intended to diagnose, treat, cure or prevent any disease.

The accuracy of this information was checked and approved by Clicks' pharmacist Waheed Abdurahman in September 2015