Isoleucine is an essential amino acid that is part of a branched chain amino acid group with leucine and valine. These three should always be taken together. It is one of several essential amino acids needed in the diet and humans cannot synthesize it from simpler metabolites. Young adults require about 20 mg of this isoleucine per day per kg (or about 8 mg per lb) of body weight. It can be degraded into simpler compounds by enzymes. In a rare, inherited disorder called maple syrup urine disease, an enzyme that is not functioning in the common pathway of isoleucine, leucine and valine causes the buildup of certain metabolites in the urine, resulting in the characteristic odor from which the disease gets its name.
It is needed to form of hemoglobin and regulates blood sugar levels. Therefore, if there is an imbalance, hypoglycemia could develop. It gets metabolized in the muscles and has to be taken with leucine and valine.
Almonds, beef, cashews, chicken, cottage cheese, eggs, fish, soy, lentils, liver, milk, and seeds.