Isoleucine is one of the nine amino acids essential for the proper functioning of the human body.
It is used by the body in the biosynthesis of proteins.
It can only be obtained from food and is found in meat, fish, cheese, eggs, pulses and nuts.
It has several physiological functions, such as healing wounds, detoxifying nitrogenous waste, stimulating immune function and promoting the secretion of various hormones.
It is necessary for the formation of haemoglobin and the regulation of blood sugar and energy levels.
It is mainly found in human muscle tissue.
Isoleucine is one of the three branched-chain amino acids (BCAAs), along with leucine and valine.
Compared to the other two BCAAs, it induces muscle protein synthesis and can significantly increase glucose uptake and utilisation during exercise.
Properties and virtues
Inflammation and immunology
The production of β-defensin (an antimicrobial peptide produced by the gut, skin and lungs) appears to be increased by isoleucine.
It is possible that defensins and antimicrobial peptides protect against bacterial infections.
Blood sugar
It would increase insulin secretion and promote cellular uptake and use of glucose, especially in the muscles, thus reducing blood glucose levels.
Muscles
Potentially anti-catabolic, preventing cellular breakdown at the amino acid level by reducing the rate of gluconeogenesis.
Different forms
The synthetic form is available as a food supplement in powder, capsule or tablet form. It is most commonly combined with leucine and valine, two other amino acids.
Use and dosage
Isoleucine increases glucose consumption during exercise, so it should be taken before exercise and with a carbohydrate-rich meal.
3.3 to 4.9 g plus food is the recommended dose based on animal studies.
It comes mainly from food, so depending on the amount taken at meals during the day, the additional doses will be smaller.
The total intake of isoleucine from food and supplementation will not exceed 10 grams.
Precautionary measures
It is generally safe to take and has no side effects.
Contraindications
BCAAs, which include isoleucine, are not recommended for people with amyotrophic lateral sclerosis, also known as Charcot's disease, or maple syrup urine disease.
Interactions with other medicines
The effects of mTOR inhibitors (resveratrol) can be compounded by isoleucine supplementation, which can interfere with muscle protein synthesis.
Source in food
It occurs naturally in food and is also synthesised from pyruvate to make food supplements.
In food, it is found in animal products, soya beans, legumes and nuts.
Amount of isoleucine per 100g, in descending order:
- Chick peas: 1656 mg
- Almonds: 1638 mg
- Meat: 1621mg
- Soya beans: 1407mg
- Turkey: 1279mg
- Chicken: 1225mg
- Haddock: 871mg
- Crab: 827mg
- Cod: 821mg
- Fresh cheese: 727mg
- Eggs: 660mg
- Hazelnuts: 627mg
- Brown rice: 622mg
- White rice: 544mg
- Peas: 283mg