Threonine — one of the essential amino acids that is not synthesized in the body and must be obtained from food.
It is involved in protein synthesis, the formation of collagen and elastin, supports skin and connective tissue health, contributes to the formation of antibodies necessary for the immune system, and also plays an important role in the metabolism of fats and carbohydrates.
To maintain optimal threonine levels, it is important to consider its dietary sources and adhere to the recommended intake. Both a deficiency and an excess of threonine can lead to various disorders in the body’s functioning.
Health Benefits
Threonine is involved in several vital processes:
- it is a component of structural proteins such as collagen and elastin;
- it contributes to the production of antibodies and supports immunity;
- it participates in the synthesis of neurotransmitters and supports the nervous system;
- it regulates fat and carbohydrate metabolism;
- it supports liver health and normal digestion.
Daily Requirement and Sources
The recommended daily intake of threonine is:
- for adults — 20–30 mg per kg of body weight;
- for children and adolescents — up to 30 mg per kg of body weight;
- in conditions of stress or increased physical activity — the requirement may increase.
The main sources of threonine are:
- meat (beef, chicken, pork);
- dairy products (cheese, yogurt, milk);
- eggs;
- fish (salmon, tuna);
- legumes (beans, lentils, soy);
- nuts and seeds;
- some grains (buckwheat, corn).
Possible forms and their learnability
Nutrient forms are listed from best to worst:
Symptoms and Consequences of Deficiency
A deficiency of threonine can lead to disorders in various body systems:
- deterioration of skin, hair, and connective tissue condition;
- decreased immunity and frequent infections;
- slowed metabolism and digestive issues;
- muscle weakness and dystrophy;
- increased fatigue, anxiety, and depressive states.
Possible Risks of Excess and Their Manifestations
Excessive threonine intake, especially from supplements, can cause:
- amino acid imbalance (e.g., decreased levels of methionine and leucine);
- digestive disorders (nausea, diarrhea);
- overload of the liver and kidneys;
- allergic reactions;
- metabolic disorders.
Consuming threonine up to 30 mg per kg of body weight per day is considered safe.
Where threonine matters most
Threonine is used to build proteins and is part of compounds important for mucous membranes, immune defense, and connective tissue. It is often mentioned alongside mucins, the mucus proteins that help maintain a protective layer in the gut and airways. This does not mean threonine treats the gut on its own, but adequate protein is genuinely needed for normal tissue renewal.
In keto and LCHF, threonine comes from complete protein foods: meat, fish, poultry, eggs, dairy products, and some plant sources. If the diet is too restricted in protein or calories, the issue is not one amino acid but the whole amino acid profile. With poor recovery, hair fragility, loss of muscle, or persistent fatigue, total diet quality should be assessed first.
How to use this information
Separate threonine is rarely needed for a person eating a normal diet. It is more practical to build meals so that each main meal contains a clear protein source. Collagen supplements may be useful for some goals, but they do not replace complete protein and do not cover the full set of essential amino acids.
In kidney or liver disease, serious digestive disorders, pregnancy, or complex medication use, individual amino acids should be discussed with a clinician. In these situations, both potential benefit and metabolic load matter.