Chances are you haven’t heard much about threonine, but this amino acid is involved in a range of biological processes. It’s best known for its role in forming the foundation of connective tissues like collagen and elastin.
It also helps regulate digestion, mood and muscle growth.
Essential amino acids like threonine are the building blocks of proteins. They play a vital role in the structure of our bones, muscles and skin.
When we don’t eat enough foods high in these important compounds, we can experience deficiency symptoms like mood changes, irritability, confusion and digestive problems.
This is just another reason why it’s so important to eat a well-balanced diet that included a range of high-protein foods, ensuring that you get enough essential amino acids.
What Is Threonine?
Threonine is an essential amino acid that plays an important role in regulating protein balance in the body. Because it’s considered an “essential amino acid,” that means the body doesn’t synthesize the amino acid, so we need to eat foods high in threonine to obtain it.
The threonine abbreviation is Thr, and its one letter code is T. The proper threonine pronunciation is “three-uh-need.”
The threonine formula is C4H9NO3, and it contains an a-amino group, a carboxyl group and a side chain containing a hydroxyl group. This makes the threonine structure a polar, uncharged amino acid.
Thr amino acid occurs naturally in the L-form, L-threonine. It’s a conjugate base of L-threoninium and a conjugate acid of L-threoninate.
Here are some common questions about the structure of threonine amino acid:
- How many stereoisomers does threonine have? Thr has four possible stereoisomers: (2S,3R), (2R,3S), (2S,3S) and (2R, 3R).
- Is threonine positively charged? T amino acid is considered to have polar properties.
- Is threonine acidic or basic? Thr is considered polar, while amino acids lysine and arginine are considered basic and charged, and aspartate and glutamate are acidic and negatively charged.
- What is the threonine codon code? The possible threonine codons include ACA, ACC, ACG and ACT.
Amino acid T is a precursor to serine and glycine, two other amino acids that are needed for the body to function properly.
Glycine is a conditionally essential amino acid, which means that it’s made in small amounts by the human body. It’s also available in foods, and many people can benefit from consuming more from their diets.
This is especially true if the person has a medical condition that limits the synthesis of glycine.
1. Supports Digestive Health
Threonine protects the digestive tract by producing a mucus gel layer that covers it and serves as a barrier to damaging digestive enzymes. This important amino acid also supports healthy gut function by promoting the protective effects of the gut mucus barrier.
According to research published in Frontiers in Bioscience, a large proportion of dietary threonine is utilized for intestinal-mucosal protein synthesis. For this reason, consuming Thr foods may help to improve gut health under physiological and pathological conditions in both humans and animals.
2. Boosts Immune System
We need enough Thr to support proper immune function. The thymus gland uses the essential amino acid to make T-cells, or T lymphocytes, that work to fight off infections inside the body.
Research published in Cold Spring Harbor Perspectives in Biology states that “serine/threonine kinases control the epigenetic, transcriptional and metabolic programs that determine T-cell function.” Researchers explain that at a basic level, serine and threonine kinases work as a series of on/off switches that trigger antigen and cytokine receptors that make up the immune system.
3. May Improve Muscle Contractions
Although more research is needed to further understand its role, there is some evidence that Thr may benefit symptoms of ALS, aka Lou Gehrig’s disease. Thr amino acid works to increase glycine levels in the central nervous system.
Glycine is used to treat spasticity, which is why L-threonine has been assessed for its ability to improve spasticity, or contracting muscles, in ALS patients.
In a review conducted in Australia, researchers found that a double-blind, placebo-controlled study of oral L-threonine to treat spinal spasticity indicates a modest antispasmodic effect. However, studies involving ALS patients show no improvements with L-thr treatment.
These mixed reviews suggest that using L-threonine supplements may help reduce muscle contractions but may not be effective for ALS symptoms.
4. Supports Muscle and Bone Strength
Did you know that collagen and elastin proteins need threonine for proper production? You may already know that collagen is the most abundant protein in the body, and it’s found in our muscles, bones, skin, blood vessels, tendons and digestive system.
Because Thr allows for the production of collagen, it plays a vital role in the health of your bones and muscles.
Research conducted Texas A&M University indicates that glycine from threonine, proline and hydroxyproline contributes to 57 percent of total amino acids in collagen. Thr amino acid is a precursor to glycine, which is also used during the biosynthesis of creatine, providing muscles with a direct source of fuel to repair damage.
Threonine also allows for proper elastin function. Elastin is a protein that’s found in connective tissue and lets the skin, tendons and ligaments resume shape after stretching or contracting.
5. Helps Prevent Fatty Liver
Thr amino acid prevents fat buildup in the liver. It does this by regulating fat metabolism and facilitating lipotropic function.
Liptropic compounds work to break down fat during metabolism, and without the amino acids threonine, methionine and aspartic acid, this wouldn’t be possible. Threonine deficiency can lead to fatty liver and even liver failure.
An animal study published in the American Journal of Physiology found that Thr-deficient diets increase mitochondrial uncoupling in the liver. This means that diets lacking quality protein foods that provide essential amino acids can lead to cell malfunction and the buildup of fats in the liver.
6. May Alleviate Anxiety and Mild Depression
Studies shows that alternations in serum levels of amino acids, including serine and glycine, which require Thr for production, are linked to major depression. Researchers in Belgium found that changes in levels of threonine, aspartate, asparagine and serine may predict a patient’s response to treatment with antidepressants by modulating amino acid levels in the body.
Because Thr is a precursor to glycine, which helps calm nerves and support cognitive health, it’s often used as a supplement to relieve signs of anxiety and depression. Glycine is also known for its ability to help improve sleep, mental performance, mood and memory.
7. Accelerates Wound Healing
Threonine is needed for the proper production of collagen, which is required for connective tissue formation and wound healing.
Research shows that after experiencing burns or trauma, individuals have greater urinary spill of threonine. This indicates that the amino acid is metabolized from body tissues after an injury.
Increasing your intake of Thr through amino acid T foods or supplements may help speed healing of wounds, burns and other forms of trauma.
Deficiency Symptoms and Causes
Threonine deficiency is rare, as most people get enough of the amino acid in the foods they eat. However, people with an unbalanced diet, vegans and vegetarians, may not consume enough threonine foods, which can cause low levels of the amino acid.
Thr deficiency may cause the following symptoms:
- digestive problems
- irritability or emotional agitation
- increased liver fat
- poor nutrient absorption
Foods and Supplements
What is threonine found in?
Amino acid T is found in nature in L-threonine form. A well-balanced diet that includes high-quality protein foods will provide the body with enough to maintain normal levels.
The top threonine foods include:
- Organic meat (including chicken, lamb, beef and turkey)
- Wild-caught fish (including wild salmon)
- Dairy products
- Cottage cheese
- Sesame seeds
- Pumpkin seeds
- Kidney beans
Thr deficiency is rare for people who eat a well-balanced, high-protein diet. For vegans and vegetarians, eating beans, seeds and peas will help maintain normal levels.
L-threonine powder and capsules are available online or in most health food stores. You may also find that elastin supplements contain L-threonine.
How to Take and Dosage
You’ll likely find threonine supplements as 500-milligram capsules that can be taken up to three times daily, depending on your health needs and level of T amino acid deficiency.
The most common L-threonine dose is 500–1,000 milligrams daily. Research suggests that doses up to four grams per day for 12 months are likely safe.
If you use L-threonine to reverse a deficiency or improve symptoms of any health condition, do it under the care of a doctor or health care professional.
There are so many ways to incorporate Thr into your diet. Focus on getting enough protein in your meals.
You can do this with organic meats, wild-caught fish, eggs, beans, nuts and seeds. Here are some healthy and delicious recipes to get you started:
- Pecorino Mushroom Chicken Recipe: This is a low-carb, gluten-free and keto-friendly chicken recipe that also includes mushrooms, ghee, cloves and pecorino cheese.
- Heart-Healthy Eggs Benedict Recipe: This healthy version of eggs Benedict is made with anti-inflammatory foods like avocado, asparagus and tomato.
- Turkey Chili with Adzuki Beans Recipe: This combination of turkey and beans is high in this amino acid. In addition to protein, this recipe is also high in healthy fats and iron.
Risks and Side Effects
Although supplementing with threonine in appropriate amounts is generally considered safe, some people may experience minor side effects, such as headache, nausea, upset stomach and skin rash.
There is not enough evidence to recommend that women who are pregnant or breastfeeding should take threonine supplements. Instead, it’s best to get enough of the amino acid from a well-balanced diet.
People taking NMDA antagonists called memantine (Namenda), which are a type of medication for Alzheimer’s disease, should avoid using this supplement. The amino acid may reduce how well these medications work.
- What is the function of threonine? The threonine definition is an essential amino acid that plays an important role in regulating protein balance in the body.
- Benefits of this amino acid include its ability to support digestive health, boost the immune system, improve muscle strength, reduce muscle spasms, relieve anxiety and mild depression, and speed wound healing.
- What foods are high in threonine? High-quality protein foods, including organic meats, wild-caught fish, eggs, organic dairy products, seeds and beans are high in the Thr amino acid.
- For those who aren’t getting enough Thr in their diets, supplementing with it may help to maintain normal levels. Capsules and powders are available online and in health food stores.