Threonine with symbol T or Thr, is an amino acid which is used in biosynthesis of proteins. It encloses a α-amino group, a carboxyl group and a side chain which contains a hydroxyl group making it a polar or uncharged amino acid. It is fundamental in humans which mean the body cannot synthesize it so it should be obtained from the diet. It is synthesized from aspartate in bacteria such as E. coli. It is encrypted by all the codons starting AC (ACT, ACA, ACC and ACG).

It is an amino acid which is common in various proteins and together with serine or tyrosine is one of three proteinogenic amino acids carrying an alcohol group. Similar to serine, threonine in significant amounts in outer regions of soluble proteins being hydrophilic in nature. Accompanying easily removed hydrogen on hydroxyl side chain, threonine is hydrogen donor in enzymes. L-isomer is the only form which is involved in protein synthesis being one of the 20 standard amino acids common in animal proteins and needed for normal functioning in humans. It is also regarded to be essential amino acid as it could not be incorporated by human body from other compounds by chemical reactions and yet should be obtained with diet.

It is an immunostimulant which enhance growth of thymus gland. It could promote cell immune defense function. This amino acid is useful for treating genetic spasticity disorders and multiple sclerosis at one gram regularly. It is high in meat products, wheat germ and cottage cheese. In infant formulas, threonine content is 20% higher than threonine concentration in human milk. With this high content of threonine, the plasma threonine concentrations are twice high in premature infants who fed these formulas than infants who fed human milk. Whey proteins used for infant formulas are sweet whey proteins which result from cheese production. Increase threonine plasma concentrations leads to accumulation of threonine or glycine in brain. This accumulation affects balance of neurotransmitter with consequences for development of brain during early postnatal life. Hence, excessive intake of threonine during infant feeding should be avoided.

History

It was the final of 20 common proteinogenic amino acids which was discovered in 1936 by William Cumming Rose hook up with Curtis Meyer. This amino acid was named as threonine due to its similarity in structure to threonic acid which is a four-carbon monosaccharide having molecular formula C4H8O5.

Threonine Food Sources

Food name	Weight (g)	Threonine (g)	DV%
Turkey	863	11	625%
Spirulina	112	3	170%
Soybeans	186	3	170%
Lupins	180	2	113%
Winged beans	182	2	113%
Kidney beans	184	1	56%
Hyacinth beans	210	1	56%
Tuna	146	1	56%
Whelk	85	1	56%
Mungo beans	207	1	56%
Chicken	140	1	56%
Lima beans	202	1	56%
Goose	143	1	56%
Tilefish	150	1	56%
Yardlong beans	167	1	56%
Salmon	143	1	56%
Parmesan cheese	100	1	56%
Kielbasa	370	1	56%
Navy beans	208	1	56%
Rainbow trout	143	1	56%

Health Benefits of Threonine

Threonine reinforces cardiovascular, central nervous, liver and immune system function. It aids synthesis of glycine or serine which are two amino acids assisting production of elastin, collagen and muscle tissue. It builds strong bones as well as tooth enamel. It speeds recovery process of injury by enhancing immune system. With the amino acids methionine and aspartic acid, it assists liver to digest fats or fatty acids, lowering fat accumulation in the liver. Accumulation of fats in liver negatively affects its function.

Digestive health

L-threonine is involved in upper reaches of small intestines. It protects digestive tract. Threonine is required for producing mucus gel layer which covers digestive tract. This mucus is an obstruction to digestive enzymes which damages intestines. Threonine is used in endogenous secretions. This amino acid is required to support healthy gut function. Study conducted on pigs, chicken and rats resulted that diet low in threonine results digestive problems and lowers immune function. It is due to decline in gut mucus barrier.

Strengthen immune system

L-threonine assists in production of antibodies to enhance immune system. The thymus gland is responsible to make T lymphocytes. It combat infections and thymus uses threonine for making T-cells. It ensures that body has adequate threonine for supporting immune function which is essential to safeguard host of diseases.

Liver function

With amino acids such as aspartic acid and methionine, threonine works together to support liver function. It facilitates lipotropic function. The body digest fats. In body with threonine deficiency, liver becomes overwhelmed by fats.

Supports muscles, bones and connective tissues

Structural proteins such as elastin and collagen need threonine. Amino acid is a precursor for glycine and serine. These amino acids are essential for forming these proteins. Collagen is the most sufficient structural protein in the body. It is an ample structural protein in the body. It is crucial for connective tissue maintenance and formation. It supports elastic muscles or connective tissues in the body. This amino acid helps to accelerate wound healing and bones after injury.

Promote cognition

In central nervous system, threonine is found in high concentrations. Studies are conducted on use of amino acid for treating Amyotrophic Lateral Sclerosis. Research conducted on potential of threonine to assist symptoms of Multiple Sclerosis including reduction in spasticity. More studies found that threonine helps to combat depression and promote mental health.

Treat depression

Supplements of threonine are found to be helpful when depression is related with leaky gut symptoms such as food allergies and celiac disease. Same effect is observed by eliminating offending food from diet but could be easier and faster to improve mucin production with supplements of threonine to improve body energy.

Spastic muscle movements

Glycine restrains transmission of random nerve impulses from brain. Threonine is transformed into glycine. Studies have shown that threonine (1000 mg) a day helps to lower but does not eliminate spastic muscle movements caused by multiple sclerosis or familial spastic paraplegia.

Maintain skin health

It is used for forming two most vital substances for connections in the body- elastin and collagen which plays crucial role to maintain healthy joints and skin. It is essential to maintain proper balance of protein and prevent formation of fat in liver. Basically, this essential amino acid is helpful to build tooth enamel and strong bones.

Sound sleep

According to CDC, more than 1/3 of adults in United States sleep low than 6 hours per night. Its main causes are technology, stress, energy drinks, prescription medications and lack of physical exercise. Research shows that this amino acid helps one to get sound sleep.

Cure celiac disease

Celiac disease is regarded as a long term autoimmune disorder which affects small intestine. People with this condition when consume foods with gluten, their immune system intervenes small intestine. This condition shows common symptoms such as mouth ulcers, constipation, bone or joint pain, fatigue, cramping, diarrhea, abdominal bloating, unexplained weight loss, moodiness and irritability. Intake of foods rich in these amino acid lower symptoms of celiac disease.

Low or High Intake of Threonine

Deficiency of threonine causes symptoms such as confusion, emotional agitation, fatty liver (leading to liver failure) and digestion difficulties. High doses of threonine could mess up with liver function and cause too much formation of urea and ammonia toxicity in the body.