What Is Threonine, And Why Is It Important?

Threonine is an essential amino acid that we rely on for the formation of collagen, to help regulate digestion, mood, and the immune system, and for fat metabolism, among other functions.

Amino acids are the building blocks of protein. There are 20 different kinds of amino acids, and they each play their own crucial roles. 

Threonine is one of nine essential amino acids– essential, in this case, meaning that our bodies can’t produce it on their own, and therefore it must be obtained through our diet (or supplements). 

So what is threonine’s role specifically, how do you know if you’re getting enough of it, and when might it make sense to take a threonine supplement? Let’s get into the details. 

Threonine’s Role In The Body

Threonine plays a number of important roles in the body. Remember that amino acids are building blocks. Threonine is required for the synthesis of glycine and serine, two different amino acids that are in turn needed for the production of the proteins collagen and elastin (1). Collagen and elastin are then used to make up the body’s muscles, bones, skin, and connective tissues. 

Beyond collagen and elastin production, threonine helps to maintain liver function, supports a healthy gut and immune system, enhances fat metabolism, helps to support mental health, and may help to improve muscle contractions. 

Threonine deficiency, like most amino acid deficiencies, is uncommon, especially if you eat a balanced diet. However, if you are not getting enough protein (especially from complete protein sources, meaning those that contain all nine amino acids), you may not be taking in enough threonine. 

Symptoms of threonine deficiency may include: 

Digestive issues

Fatty liver disease

Slower wound healing

Brain fog or confusion 

Fatigue

Irritability

Muscle weakness or loss 

Keep in mind that these symptoms may be related to any number of dietary insufficiencies or other imbalances, and threonine deficiency is not necessarily the first place you’ll want to look. However, if you’re experiencing these symptoms and not sure if your protein intake is adequate, it’s worth exploring.

How To Obtain This Essential Amino Acid

The best (and most common) way to obtain threonine is through our diets. Threonine is found in a wide variety of protein-containing foods, and if you’re eating a well-balanced diet, you’re most likely getting enough of this and other amino acids through what you eat. 

But there are some exceptions. When it comes to protein, we often focus on how much is being consumed, but it’s equally (if not more) important to consider what kinds of protein we’re eating. 

All protein foods contain amino acids. But they don’t all contain all of the nine essential amino acids we need to obtain through diet. 

Foods that do contain all nine essential amino acids are referred to as complete proteins. Some of the best known complete protein sources are animal products like beef, poultry, fish, and eggs. 

There are also a number of plant-based complete proteins, including tempeh, natto, hemp, and nutritional yeast. 

Incomplete proteins can also be excellent sources of amino acids (and other nutrients). The trick is just to make sure that you’re eating enough of a spectrum of them to cover all nine of your amino acid bases. 

Here are some of the best food sources of threonine: 

Organic meat and poultry (including chicken, turkey, beef, lamb) 

Wild-caught fish

Eggs

Oats

Cottage cheese

Wheat germ

Peas

Spirulina 

Tofu

Sesame and pumpkin seeds

Kidney beans 

Lentils

Bananas 

Those who don’t consume enough protein (or enough complete protein, or enough variety) may be more at risk of a threonine deficiency. 

If, due to a limited vegan or vegetarian diet, or any other reason, you’re not getting enough threonine through food sources, threonine can also be taken as a supplement. Supplements may be sold as powders or capsules and can be found at health food stores. 

LISTEN: Essential Amino Acids For Longevity + Metabolism (Myths, Plant-Based Vs. Animal Protein, Food Combining) With Angelo Keely 

How It Benefits Your Health

Threonine plays a number of important roles in the body, and may offer additional benefits for some people if taken supplementally or consumed in higher quantities through diet. 

Potential benefits of threonine may include: 

Improving muscle spasticity. Supplemental threonine has been researched for its potential role in improving muscle control, involuntary movements, and spasticity (muscle contractions) for those with amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and related disorders. This is due to threonine’s role in natural glycine synthesis, as glycine is known to reduce spasticity. However, studies on threonine supplements for this purpose have shown mixed results so far (2, 3). 

Helping to produce collagen, elastin, and muscle tissue. Threonine helps to support the strength, health, and recovery of our muscles, bones, skin, and connective tissue through its role in the synthesis of glycine and serine.

Supporting gut health. Threonine helps to form the protective mucus layer that serves as a barrier for the digestive tract (keeping unwanted substances from entering) (4). 

Reducing anxiety and mild depression. Lower levels of glycine and serine have been linked to depression. As threonine is used for the natural production of these amino acids, it may have a role in supporting mood and mental health (5). Glycine also plays a role in reducing anxiety, improving cognition, and promoting a healthy sleep cycle. 

Enhancing immune system function. The immune system uses threonine to help make T-cells, which we use to help fight infections and disease (6). If threonine levels are low, supplements could theoretically help to improve resistance to illness. 

Regulating fat metabolism and liver function. Threonine may help to prevent fatty liver disease by facilitating efficient fat metabolism in the liver (7).

Accelerating wound healing. Threonine is a building block of collagen, which is essential for wound healing. Research has also shown that we use up more threonine than usual after injury or trauma (8). Therefore, supplements or increased dietary intake may help to speed up the healing process during these times.

Side Effects 

Threonine supplements are generally thought to be safe for most people, with most possible side effects being mild. 

Possible side effects may include: 

Nausea or upset stomach

Headache

Skin rash 

One clinical trial looking at threonine for the treatment of muscle spasticity in patients with ALS found that the supplements seemed to worsen lung function within this population (9). This is a possible side effect that should be discussed with your practitioner if you’re looking into supplementation for spasticity or for ALS, or if you have reduced lung function. 

Those who are taking memantine (Namenda), an NMDA antagonist used for Alzheimer’s, should avoid taking threonine as it may interfere with the medication. 

These potential side effects relate to supplemental threonine specifically. When it comes to the threonine we consume naturally through diet, there are no known risks or side effects. 

Take Control Of Your Health Today

Threonine is an essential amino acid that we rely on for numerous important functions, from collagen production and gut lining support to immune system function and fat metabolism. 

To ensure adequate daily intake of threonine and other amino acids, you’ll want to make sure to consume complete proteins, or at minimum a wide variety of incomplete proteins. Make sure to keep in mind quality, not just quantity, when it comes to protein. 

Curious If Threonine Is Right For You?

If you’re curious about what supplements might be best for you, whether you’re getting enough balanced protein in your diet, or how to more generally supercharge your health, consider booking a virtual consultation through our functional medicine practice. We’d love to help.