Threonine: An Essential Amino Acid for the Liver System

Threonine is an amino acid capable of intervening in the metabolism of fatty acids, as well as in the Krebs cycle. We are going to explain its importance in the human organism.

Written and verified by el nutricionista Saúl Sánchez.

Last update: 28 March, 2021

Threonine is considered to be an essential amino acid. This means that the human body isn’t capable of synthesizing it by itself. For this reason, it must appear in the diet on a regular basis. However, through the consumption of proteins of animal origin, the needs of the nutrient can be satisfied.

Before starting, it should be noted that proteins of animal origin have a higher biological value than those of plant origin. This means that they aren’t lacking in any of the essential amino acids, in addition to having a good score in terms of digestibility.

How is threonine obtained?

As we have commented, threonine can be found in proteins, and these are an element that forms them. It’s usually obtained in a laboratory through a fermentation mechanism, mediated by microorganisms such as yeasts.

However, it can also be isolated by hydrolysis techniques, although this is a method that is usually only carried out for pharmaceutical purposes.

In nature, threonine is generated from the action of certain enzymes that convert aspartic acid. The main function of this amino acid is to participate in the metabolism of fats that will be deposited in organs for their reserve, such as the liver. This is evidenced by a study published in the journal Biochemistry.

Threonine sources

Threonine can’t be synthesized in the body, and so it must be introduced through the diet. Otherwise, there would be a deficit that would put a person’s health at risk.

Almost all foods of animal origin have threonine in their composition, as a protein-forming element. For example, fish, eggs, dairy, and meat contain a more than optimal contribution of the nutrient.

If these foods appear in the diet frequently, then it wouldn’t be necessary to worry about the presence of this nutrient in the body, as the requirements would be more than met.

Even many plant-based proteins also have threonine in them. Fruit is a good source of this nutrient, which can also be found in nuts and seeds.

Since both animal and vegetable products contain significant amounts of this amino acid, there’s no risk of suffering from a deficiency in the context of a restrictive diet, such as a vegan diet.

Threonine functions

Threonine performs various functions within the human body. It stands out for being able to be transformed into glucose and glycogen in the liver, through various metabolic pathways. This process is known as gluconeogenesis, and it allows the human body not to run out of fuel in situations where the dietary intake of sugars is insufficient.

On the other hand, threonine plays a decisive role in limiting the risk of developing fatty liver disease, as evidenced by research published in Hepatology Communications.

However, it must be taken into account that the study was carried out in mice and that it didn’t conclude that an increase in the supply of this nutrient reduces the incidence of the disease.

This amino acid could decrease the prevalence of certain degenerative diseases such as arthritis. In this sense, its contribution may represent a turning point in the treatment of problems such as sprains or tendinitis, although protocols and more research into its use do need to be established.

Among the pathologies that occur with tissue degeneration, the nutrients that have been shown to be most effective are those that can modulate inflammatory processes, such as curcumin. This is confirmed by a study published in the Journal of Medicinal Food.

Of course, in this scientific literature, it’s possible to find tests carried out in animals that suggest that high doses of threonine could be beneficial for problems related to the mucous membranes and organs of the digestive system.

It could even exert a protective effect against the development of certain inflammatory processes mediated through tumor necrosis factor.

Threonine and liver health

It’s clear that a good part of threonine metabolism takes place in the liver. This is where it can be transformed into glucose for use as a substrate, but it’s also the place where the physiological processes of energy creation are set in motion, and this is where threonine is actively involved.

In fact, experts affirm that this amino acid is an important element in the Krebs cycle, necessary for the production of energy, and also in the detoxification of the liver tissue itself, through the synthesis of collagen and the physiological processes that have to do with the creation of fat.

A deficit of the nutrient in the body could increase the risk of developing pathologies such as nonalcoholic fatty liver, which is generally difficult to manage, leaving sequelae or conditioning lifestyle habits.

It should be noted that there are several foods or nutrients capable of promoting liver function. For example, milk thistle is used frequently to improve the management of liver problems caused by drugs, as evidenced by a study published in Medicine.

Threonine and microbiota

Threonine is not only capable of causing benefits for the liver. Certain recent studies, although carried out in animals, suggest the importance of this amino acid in ensuring a correct composition of the intestinal microbiota.

In fact, an adequate consumption of the nutrient is related to a lower risk of developing problems associated with the digestive tract.

However, human studies are needed to confirm this theory, as most of those carried out to date have been carried out in rodents or birds. Even so, it’s possible that guaranteeing a correct and continuous supply of threonine is a key factor in avoiding alterations in the bacteria that inhabit the intestine.

In any case, the composition of the microbiota is a parameter that depends on many different factors at the dietary level. The intake of fermented foods or fiber can have a much more decisive impact than the contribution of an amino acid in isolation.

Other important amino acids

Not only is threonine important in the body, but many other amino acids also have essential functions that can prevent the development of complex conditions that can affect our health. In this sense, we can highlight glutamine. This nutrient is capable of improving intestinal function, and is essential for the repair of the digestive tract tissue.

Likewise, leucine is another of the amino acids that performs vital functions in the human body. It’s a key element when it comes to carrying out the mechanisms related to the repair or growth of muscle tissue. In athletes, the requirements are increased.

However, one of the differences of threonine when compared to the two amino acids mentioned is that its supplementation isn’t thought to be beneficial. However, it is common to find products on the market with glutamine or leucine, especially for use in sports or hospitals.

However, there’s no such thing as a threonine supplement, as a greater intake of this element hasn’t been shown to be beneficial.

The importance of guaranteeing protein intake

You’ve probably already heard on more than one occasion that it’s essential to meet your daily protein requirements. These nutrients are broken down into amino acids within the human body, which are used for various functions.

Current nutrition guidelines are committed to guaranteeing a contribution of at least 1.2 grams of protein per kilo of body weight per day, and this amount can be increased in the case of regular physical exercise.

It’s also important for at least half of these nutrients to come from foods of animal origin. As we’ve already indicated, these proteins have a higher biological value, and so they’re not lacking in any essential amino acids. They also have optimal digestibility levels.

Even so, we mustn’t neglect vegetable intake, as they also provide good protein content, as well as important phytonutrients for the prevention of chronic and complex diseases.

If you have any questions about whether the protein intake in your diet is correct, then it’s best to consult a nutritionist. They may make adjustments to your diet in order to maximize your protein content. In addition, they can also recommend a protein supplement if necessary.

Threonine, an important amino acid for the liver

As you’ve seen, threonine is an essential amino acid that plays an important role in metabolism and liver health. However, there are still certain questions regarding the role it plays in specific physiological mechanisms. This is why several investigations are underway that will clarify these processes.

It’s a nutrient that has been extensively studied in animal metabolisms, but not so much in humans. What’s clear is that an inadequate intake of this amino acid in the diet can negatively impact liver health, increasing the risk of becoming ill.

Fortunately, this element can be found in many foods, both of animal and vegetable origin. In this sense, it’s difficult to experience an amino acid deficiency if you have a varied diet.