Discover how isoleucine can help improve your health and wellbeing


The discovery of isoleucine can be traced back to the early 20th century when a German chemist named Felix Ehrlich was studying the composition of hemoglobin, a protein found in red blood cells that is responsible for carrying oxygen throughout the body. At the time, scientists were just beginning to understand the chemical structure of proteins and the role that different amino acids played in their formation.
In 1903, Ehrlich published a paper in which he described a new amino acid that he had isolated from hemoglobin. He called this amino acid “isoleucine,” as it was similar in structure to the leucine amino acid, already discovered. Ehrlich’s discovery was significant because it was the first time that an amino acid had been isolated from a protein in pure form.
Ehrlich’s discovery was met with skepticism by some scientists, who believed that the new amino acid was simply a product of the degradation of other amino acids during the isolation process. However, further research confirmed that isoleucine was indeed a distinct amino acid and that it was an important component of many proteins.
Ehrlich’s discovery of isoleucine was a major step forward in the field of protein chemistry and laid the foundation for further research into the structure and function of proteins and the role of individual amino acids in their formation. Today, isoleucine is considered one of the 20 essential amino acids and is known to play a vital role in muscle growth and repair, blood sugar regulation, and other metabolic processes.

Original By Ben Mills – Own work, Public Domain

Isoleucine Health Benefits

Isoleucine has several important functions in the body.
  • Isoleucine is involved in the production of hemoglobin, the protein found in red blood cells that is responsible for carrying oxygen throughout the body. Hemoglobin is made up of four subunits, each containing a heme group and a protein chain called a globin. The globin chain is made up of a specific sequence of amino acids, including isoleucine.

Hemoglobin must maintain a specific shape in order to effectively bind oxygen and transport it throughout the body. Isoleucine, along with other amino acids, helps to maintain this shape by forming hydrophobic interactions with other molecules.

  • Isoleucine plays a role in the regulation of blood sugar levels by stimulating the release of insulin. Insulin is a hormone produced by the pancreas that helps to regulate the uptake of glucose by cells, thus keeping blood sugar levels within a normal range.

One of the ways in which isoleucine helps to regulate blood sugar levels is through its involvement in the process of gluconeogenesis. Gluconeogenesis is the production of glucose from non-carbohydrate sources such as proteins and fats. During periods of low carbohydrate intake, the body can use isoleucine and other amino acids as a source of glucose to maintain blood sugar levels.


Original By Ben Mills – Own work, Public Domain.

  • Isoleucine also has the ability to stimulate the release of insulin from the pancreas, which helps to lower blood sugar levels by promoting the uptake of glucose by cells. This is a unique property of isoleucine and other branched-chain amino acids (BCAA) like leucine and valine. Studies have shown that consuming a diet high in BCAA can lead to increased insulin sensitivity and a reduction in blood glucose levels.
  • Isoleucine, along with the other two branched-chain amino acids (BCAA) leucine and valine, plays a role in energy metabolism by providing energy to muscles during exercise.
During exercise, muscles use glucose as a primary source of energy, but as the intensity and duration of the exercise increases, the muscle’s ability to use glucose decreases, and muscles start to rely on BCAA for energy. Isoleucine is broken down in the muscles to produce energy, and it can also be converted into glucose through gluconeogenesis, which helps to maintain blood sugar levels during exercise.
  • Isoleucine also plays a role in muscle recovery after exercise. The breakdown of muscle tissue during exercise can lead to muscle damage, which can cause inflammation, pain, and delayed muscle recovery. Isoleucine helps in the repair and growth of muscle tissue by providing the necessary building blocks for protein synthesis. Studies have shown that supplementation with BCAA, including isoleucine, before or after exercise can reduce muscle damage and promote muscle recovery.

Foods rich in Isoleucine

Isoleucine can be found in a variety of foods, including both animal and plant-based sources.
  • Animal sources of isoleucine include meat, fish, poultry, eggs, and dairy products. High-quality sources include lean meats such as chicken, turkey, and lean cuts of beef and fish, as well as eggs and dairy products like cheese, milk, and yogurt.
  • Plant-based sources of isoleucine include legumes such as beans, lentils, and peas, nuts, and seeds such as soybeans, pumpkin seeds, almonds, and sesame seeds, and whole grains like wheat germ, quinoa, and amaranth. Some fruits and vegetables like avocados, spinach, and kale contain isoleucine.
Isoleucine can also be obtained through dietary supplements, such as protein powders and amino acid supplements. These supplements can be useful for people who have difficulty getting enough isoleucine from their diet, such as vegetarians and vegans, and for athletes and bodybuilders who need extra isoleucine for muscle recovery.

Recommended daily intake

The recommended daily intake of isoleucine can vary depending on factors such as age, sex, and level of physical activity.
The recommended daily intake of isoleucine for adult men and women is 12 mg per kg of body weight per day, according to the World Health Organization (WHO).
For example, a sedentary adult man with a body weight of 70 kg should consume about 840 mg per day, for a sedentary adult woman weighing 60 kg should consume about 720 mg per day.
The recommended intake may be higher for people who are pregnant or breastfeeding, as well as for athletes and bodybuilders who need extra isoleucine for muscle recovery.

Isoleucine deficiency

A deficiency of isoleucine is relatively rare since this amino acid is found in a wide variety of foods and is usually easy to obtain through a balanced diet. However, in some cases, it may be necessary to pay special attention to ensuring that enough isoleucine is consumed, particularly for vegetarians and vegans who may not consume enough from animal sources.
Some possible symptoms of an isoleucine deficiency include fatigue, muscle weakness, and decreased endurance. People with a deficiency may also have a reduced ability to repair damaged tissues and a weaker immune system.
A deficiency can occur in certain medical conditions, like maple syrup urine disease. It’s an inherited disorder of amino acid metabolism where there’s a deficiency in enzymes that break down certain amino acids, causing an accumulation of these amino acids in the blood and urine, leading to symptoms like vomiting, difficulty breathing, and intellectual disability.
A deficiency is usually treated by increasing the intake of foods rich in isoleucine. Some people may also need to take dietary supplements if they are not able to get enough isoleucine through their diet. It’s important to consult a medical professional if you suspect you may have an isoleucine deficiency or have any concerns about your nutrient intake.

Isoleucine excess

Consuming too much isoleucine is not common, but it is possible to consume too much of any nutrient if large doses of dietary supplements are taken. The safe upper limit for isoleucine has not been established, however, excessive consumption of any amino acid can cause imbalances in the body which can lead to negative effects.
Some possible symptoms of excessive isoleucine intake include nausea, diarrhea, and abdominal cramps. High levels of isoleucine can also disrupt the balance of other amino acids, leading to muscle tissue breakdown, which may increase the risk of kidney stones and gout. Excessive consumption can also lead to an imbalance in other branched-chain amino acids, leading to hyperammonemia, which can cause neurological symptoms like confusion, drowsiness, and even seizures.
It’s important to consume amino acids in appropriate amounts, a balanced diet usually provides enough isoleucine and other essential amino acids. It’s not recommended to consume high doses of isoleucine or other amino acids in the form of supplements unless advised by a healthcare professional and under close monitoring.

Fun facts

  • Isoleucine is named after the Greek word “isos” meaning “equal” and “Leucos” meaning “white”, referring to the fact that this amino acid is chemically similar to leucine.
  • Isoleucine is one of the three branched-chain amino acids (BCAAs) along with leucine and valine. BCAAs are unique in that they are metabolized in the muscle, rather than in the liver.
  • Isoleucine’s ability to form hydrophobic interactions with other molecules helps to stabilize the three-dimensional structure of proteins, making them more resistant to changes in temperature and pH.
  • Isoleucine has been used in some studies as a treatment for some diseases such as Phenylketonuria, which is a genetic disorder that causes an amino acid called phenylalanine to build up in the body.
  • Isoleucine is also important for bodybuilders, isoleucine supplement has been found to be beneficial for muscle strength and endurance.

Why is Isoleucine important for sports performance?

Isoleucine is an important amino acid for sports performance for several reasons.
As one of the branched-chain amino acids (BCAAs), isoleucine plays a critical role in muscle recovery and repair.
During intense physical activity, muscles undergo microtrauma, small tears, and damage, isoleucine helps in the repair process, by providing the body with the necessary building blocks to repair and rebuild the muscle tissue. This can help to reduce muscle soreness, fatigue, and injury.
Isoleucine also plays a role in energy metabolism, which can help to provide energy to muscles during exercise. During exercise, muscles use glucose as the primary energy source. However, when glucose is low, the body can use isoleucine as an alternative source of energy. This can help to improve athletic performance and delay fatigue.
Isoleucine can help in the regulation of blood sugar levels by stimulating the release of insulin. Insulin is a hormone that helps to regulate the amount of sugar in the blood, which is important for maintaining energy levels during exercise.
Isoleucine supplementation has been found to be beneficial for muscle strength and endurance in athletes, bodybuilders, and other people involved in intense physical training, by helping to reduce muscle soreness, fatigue, and injury. As a result, isoleucine is an essential nutrient for sports performance, recovery, and maintaining a healthy muscle mass, but as always, it’s important to make sure that it’s consumed in appropriate amounts and not to rely on supplements alone, a balanced diet should be the first source.

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