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Supplement Facts & Directions

Supplement Facts

Serving Size: 1000 milligrams
Servings Per Container: Varies
Amount Per Serving % Daily Value*
L-Isoleucine 1000 mg

* Percent Daily Values are based on a 2,000 calorie diet.
† Daily Value Not Established
‡ These supplement facts may vary from the product you receive. Please call for exact numbers.

Other Ingredients: None


Free of: Soy, Dairy, Yeast, Gluten & Additives.

Directions: As a dietary supplement, take 1000 mg up to twice daily, or as directed by a physician. Accurate gram weight scale recommended.

Warning: If you are pregnant, nursing, taking any medications or have any medical condition consult your physician before use. Keep out of reach of children.

Product Details

What is L-Isoleucine?

L-Isoleucine, or simply isoleucine, is one of the nine essential amino acids required to sustain life. The body can’t synthesize it, so individuals must obtain isoleucine from dietary sources. Some food sources of isoleucine include eggs, cheese, chicken, turkey, lamb, fish, seaweed, and soy protein.

Isoleucine serves numerous biological functions, such as producing energy, detoxifying nitrogenous wastes like ammonia, stimulating the immune system, forming hemoglobin, regulating blood sugar, and much more. It’s a proteinogenic amino acid, meaning the body uses it to make proteins. Muscle tissues contain the highest concentrations of isoleucine, as it’s necessary for muscle metabolism. Isoleucine is also one of the three branched-chain amino acids (BCAAs), along with l-leucine and l-valine.

What Are BCAAs (Branched-Chain Amino Acids)?

BCAAs are the most anabolic of the essential amino acids, as they promote protein synthesis for better muscle growth. BCAAs make up 35% of all amino acids found in proteins and represent 40% of the total amino acids humans need to live. BCAAs are popular amongst athletes and fitness enthusiasts as they help produce energy and synthesize muscle protein. They also play a role in muscle recovery after exercise. All three BCAAs have a sidechain made up of one carbon atom and three hydrogen atoms, hence the name branched-chain.

Potential Isoleucine BCAA Benefits

Isoleucine is among the best amino acids for muscle growth. BCAAs like isoleucine help form hemoglobin and red blood cells. Researchers have also found that BCAAs help improve red blood cells’ oxygen-carrying capacity in athletes. Good blood flow is essential to deliver nutrients to muscles during exercise. Isoleucine is also the most effective BCAA for boosting muscle energy, as it is the most effective at facilitating glucose uptake into cells.

Isoleucine plays a role in protein metabolism, too. It has anabolic properties, as it stimulates muscle protein synthesis while simultaneously inhibiting the breakdown of proteins. Additionally, BCAAs like isoleucine allow muscles to recover faster from fatigue and decrease exercise-induced muscle damage. Isoleucine plays a role in ammonia detoxification by providing the carbon framework for glutamate and glutamine synthesis. These amino acids are essential for the citric acid cycle to generate and release stored energy.

Potential Isoleucine BCAA Side Effects

Most individuals can take BCAAs without experiencing adverse effects. However, BCAAs work best for muscle protein synthesis when taken together. Some individuals may experience gastrointestinal side effects while taking BCAA amino acids, including nausea, vomiting, bloating, and diarrhea. Individuals with certain medical conditions should consult a physician before taking BCAA supplements. These include individuals with ALS (Lou Gehrig’s disease), branched-chain ketoaciduria (maple syrup urine disease), and individuals with liver or kidney conditions. BCAAs may affect certain medications, including those for diabetes, thyroid conditions, Parkinson’s, and steroids. Individuals preparing for surgery should cease taking BCAA supplements two weeks prior, as it may affect blood sugar control during the procedure.


Tested by Accredited 3rd Party Labs

PureBulk's supplements are tested by accredited third party labs in the USA to ensure their identity, purity and potency. To receive a copy of these test results or any other PureBulk supplement please fill out the COA request form found here.

*NOTE: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

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