Threonine is one of the 20 amino acids that constitute proteins. It is an essential amino acid and not synthesized by humans. Therefore, threonine has to be obtained from dietary sources. Threonine can exist in four possible forms or two forms of L-threonine. The name L-threonine is mostly used for one single form chemically known as (2S, 3R)-2-amino-3-hydroxybutanoic acid. L-threonine is one of three indispensable amino acids since mammals do not possess the necessary enzymes for the transamination of threonine. Another form, called L-allo-threonine, is rarely present in nature. In plants and microorganisms, threonine is synthesized from aspartic acid via alpha-aspartyl-semialdehyde and homoserine.
Threonine Deficiency:
A study with animals (piglets) has shown that threonine deficiency has caused higher nitrogen excretion and higher blood urea. Histopathological analyses showed lower number of acidic mucin-producing goblet cells in the duodenum and ileum (parts of small intestine) of pigs fed with threonine-deficient diet. Dietary threonine imbalance is known to reduce the growth of the small intestine, liver, and skeletal muscle in young animals. Piglets fed deficient threonine diets had smaller intestinal weights, less mucosal tissue (the absorptive cells of the intestine), and less intestinal mucin (Mucin is mucous that lines the interior surface of the digestive organs like small intestine) compared to control pigs.
Intestinal mucins are important in normal functioning of the intestine. Mucin prevents: digestion of the intestinal wall by digestive enzymes, water loss from the intestinal wall, bacteria from adhering to the intestinal cells and toxins from being absorbed into the body. Without enough threonine in the body, fats could build up in the liver and ultimately cause liver failure.
What is L-Threonine?
Threonine is one of the 20 most common natural amino acids that constitute proteins. It is an essential amino acid and as such it is not synthesized in the human body and because of this, L-Threonine must therefore be supplied by dietary intake of proteins containing L-Threonine or via supplementation. Threonine has four possible forms, and two forms of L-threonine. The name L-threonine is generally used for one single form chemically known as (2S, 3R)-2-amino-3-hydroxybutanoic acid. Another form, known as L-allo-threonine, is rarely present in nature. In plants and microorganisms, threonine is manufactured from aspartic acid via alpha-aspartyl-semialdehyde and homoserine.
Threonine is a main component in forming proteins, collagen, Elastin and tooth enamel. It is also crucial for the production of neurotransmitters and overall health of the nervous system. Meats in general including beef, chicken and turkey are good dietary sources L-Threonine. L-Threonine deficiencies are relative rare among people consuming a balanced diet. However, since vegetables and grains are not particularly good sources for L-Threonine strict vegetarians and vegans may want to consider L-Threonine supplementation.
Symptoms of L-Threonine deficiency included emotional agitation, confusion, fatty liver problems, and digestive problems. L-Threonine is believed by researchers to play an important role in the production of antibodies and overall immune function support. Reasons to supplement with L-Threonine include muscle relaxation, collagen health, increased antibody function, and helping to maintain proper protein physiological balance.
Research done using animals (piglets) as subjects have demonstrated that threonine deficiency can lead to higher nitrogen excretion and higher blood urea. Dietary threonine imbalance is known to reduce the growth of the small intestine, liver, and skeletal muscle in young animals. Piglets fed with threonine deficient diets had smaller intestinal weights, less mucosal tissue (the absorptive cells of the intestine), and less intestinal mucin compared to control pigs. Mucin pertains to mucous that lines the interior surface of the digestive organs like small intestine. Intestinal mucins are vital to ensure the normal functioning of the intestine. Mucin prevents digestion of the intestinal wall by digestive enzymes, retards water loss from the intestinal wall, inhibits bacteria from adhering to the intestinal cells and prevents toxins from being absorbed into the body. Without enough threonine in the body, fats could build up and impede the liver from doing its job, which can ultimately cause liver failure.
In essence, Threonine is a hydroxyl-containing amino acid, also an essential amino acid, which is an important part of many proteins in the body. It is necessary for the formation of tooth enamel and elastin and collagen which are needed for both healthy skin and wound healing, and rich dietary sources include meats and fish, dairy foods, eggs, wheat germ, bananas, carrots, nuts, beans and seeds. Threonine promotes normal growth by helping to maintain the proper protein balance in the body. Threonine also supports cardiovascular, liver, central nervous, and immune system function.
In the United States, L-Threonine is sold as a dietary supplement, and dietary supplements are regulated as foods, not drugs. Therefore, premarket evaluation and approval by the Food and Drug Administration are not required unless claims are made for specific disease prevention or treatment.
Where it is found
Foods high in threonine include cottage cheese, poultry, fish, meat, lentils, and sesame seeds.
Benefits / uses
Threonine is an important component of numerous proteins in the body and is required in forming tooth enamel, elastin and collagen, which are responsible for both healthy skin and wound healing. Threonine has a slight glucose-sparing effect and is beneficial in stabilizing blood sugar because it can be converted into glucose by the liver through the process of gluconeogenesis. Threonine can improve immunity by assisting in the production of agents that combat viral infections. It promotes cell immune defense function as well. Additionally, threonine is used to treat indigestion and intestinal malfunctions.
Threonine bolsters cardiovascular, liver, central nervous, and immune system function. Threonine assists in the manufacture of glycine and serine, two amino acids that aid in the production of collagen, elastin, and muscle tissue. Threonine also plays a huge role in building strong bones and tooth enamel, and helps keep connective tissues and muscles throughout the body strong and elastic, including the heart, where it is found in significant amounts. It also speeds up wound healing or recovery from injury by boosting the immune system. Threonine, in conjunction with the amino acids aspartic acid and methionine, can significantly help the liver in digesting and eliminating fats and fatty acids, thus reducing the accumulation of fat in the liver. A build up of fats in the liver can have adverse effects on its function. Without adequate threonine in the body, fats could accumulate in the liver and ultimately cause liver failure.
Threonine strengthens the immune system by helping in the production of antibodies, and because it is found largely in the central nervous system, it may be beneficial in treating some types of depression as well. Threonine supplementation may also be helpful in managing and treating Lou Gherigs Disease, also known as Amyotrophic Lateral Sclerosis (ALS), because it increases glycine levels in the central nervous system. Administering glycine by itself is ineffective, since it cannot cross into the central nervous system. Research indicates that symptoms of Multiple Sclerosis (MS), another disease that affects the nerve and muscle function, may be mitigated with threonine supplementation.
Doses
Threonine is available in protein supplements such as protein powder and bars, as well as in amino acid capsules and tablets. Recommended dosing for L-Threonine varies between as little as 100 milligrams per day to as much as 8 grams per day, depending upon individual needs. One level teaspoon is approximately 2671 milligrams (2.67 grams) and taken two times per day will yield an approximate daily dose of 5.3 grams.
Possible Side effects / Precautions / Possible Interactions:
Symptoms of threonine deficiency include emotional agitation, confusion, digestion difficulties and fatty liver. Exceeding the recommended doses of threonine, on the other hand, can disrupt liver function, and cause the formation of too much urea, and consequently ammonia toxicity, in your body. People with liver or kidney disease should not take this or any other amino acid supplement without first consulting their physician. Getting too much of any one amino acid can throw the citric acid cycle out of balance, which makes the liver and kidneys work harder to eliminate toxins.
Research studies / References