Maintaining health and a good appearance is an integral part of modern life. Intensive exercise, restrictive diets, especially elimination diets, can upset this balance, adversely affecting the body's supply of essential substances such as amino acids.

There are 20 protein amino acids (building blocks of proteins) and approximately 1,000 non-protein amino acids. Proteinogenic amino acids, also known as canonical amino acids, can be divided into 3 groups based on their origin: nonessential amino acids (NEAA), conditional amino acids and essential amino acids (EAA). Nonessential amino acids are compounds that the body can synthesize on its own to meet its needs. The body is also able to synthesise conditional amino acids, but in states of higher demand, these should be supplied additionally with food. Meanwhile, essential amino acids, are compounds that the human body is unable to produce on its own and must be obtained through diet.

Amino acids are the building blocks of proteins but are also involved in a numerous other metabolic pathways. On the one hand, they are the only source of nitrogen, while on the other, their carbon chains are used in gluconeogenesis and lipid synthesis. They serve as precursors and metabolites of hormones, neurotransmitters, porphyrins, purine and pyrimidine bases. They regulate intracellular metabolism, as well as cell proliferation and differentiation processes. They have antioxidant properties and stimulate the burning of adipose tissue. They regulate the immune, nervous, cardiovascular, digestive systems, and gene expression. They improve memory, perceived stress levels, sleep quality, and mood. They are essential for the proper functioning of organs.

Protein-energy malnutrition (PEM) describes nutritional macrodeficiency syndromes, including marasmus (deficiency of calories), kwashiorkor (deficiency of protein), and mixed-type malnutrition associated with hypercatabolism and insufficient protein intake.

Symptoms of protein deficiency include depression, insomnia, anxiety, fatigue, weakness, decreased muscle strength, impaired immunity, hormone secretion disorders, and growth and developmental disorders leading to physical and mental disabilities. Gastrointestinal diseases such as weakened intestinal peristalsis, impaired digestion and absorption may also appear. In severe cases, protein deficiency leads to a reduction in heart muscle mass, coma, and death. Paradoxically, in cases of kwashiorkor, weight gain can be observed due to increased water retention and oedema, mainly ascites and oedema of the lower limbs.

Equally detrimental is too much protein intake, which can result in a number of disorders such as abdominal pain, persistent constipation, increased levels of transaminases and albumin, dehydration, uric acid deposition in the joints, increased urea production, formation of kidney crystals and stones, kidney damage, metabolic acidosis, electrolyte imbalance.

Essential amino acids, in contrast to nonessential amino acids, must be obtained from food. To maintain a proper balance, the daily protein intake for a healthy adult should be 0.8 g/kg of body weight, of which 0.2 g/kg of body weight should be EAA.

It is recognised that malnutrition, including an inadequate supply of complete dietary protein, is a major problem in developing countries.

In the case of residents of Central European countries, inadequate protein supply may result from conditions of increased demand, such as periods of intensive growth, pregnancy, intensive exercise, extensive trauma, post-operative conditions, generalised inflammation with a sudden increase in caloric requirements, high fever, and chronic diseases, including cancer. In addition, the anabolic response of muscles to ingested amounts of essential amino acids decreases with age, so the consumption of higher amounts of EAA (especially leucine) is necessary for their proper functioning.

Equally important for the body's supply of nutrients are states of reduced supply, such as weight loss, anorexia, depression, neurological diseases, mental disorders, malabsorption, diseases with intense vomiting and diarrhoea, as well as states of reduced appetite occurring, for example, in the elderly or in gastrointestinal tumours.

It is also important to consider the quality of consumed protein products. It is recommended to consume so-called complete proteins, which contain all essential amino acids. These are usually proteins of animal origin. Therefore, the use of unbalanced diets, especially based on plant products, can lead to deficiencies of one or more essential amino acids necessary to maintain proper metabolic balance.

A particular group of people at risk of protein-calorie malnutrition are patients with chronic renal disease (CKD). Polish studies have shown that moderate protein-calorie malnutrition was found in 34% and severe malnutrition in 5.8% of dialysis patients. Malnutrition has been shown to be closely associated with a higher incidence of cardiovascular disease, increased hospitalisation rates, poorer quality of life, and a worse prognosis for CKD patients.

On the other hand, increased protein intake, especially of animal origin, has been linked to the development of stomach, colon, rectal, pancreatic, bladder, breast, and ovarian cancers. It also increases the risk of osteoporosis and fractures associated with increased bone resorption. For athletes, branched-chain amino acids (BCAAs), namely leucine, isoleucine, and valine, are particularly important as they improve post-workout regeneration, enhance muscle protein synthesis, and regulate hormone release. However, high BCAA levels have been linked to an increased risk of type 2 diabetes and non-alcoholic fatty liver disease. Moreover, excessive consumption of sulfur-containing amino acids has been linked to increased calcium excretion from the body and the development of bone diseases.

The amino acid profile test performed by Masdiag Laboratory is based on the determination of 26 compounds: 19 proteinogenic amino acids (canonical) and 7 key non-proteinogenic amino acids (non-canonical). The test is performed using the isotope dilution method and high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) technique. The use of LC-MS/MS provides analytical capabilities that are not achievable with other techniques. It allows for high repeatability and accuracy of measurements. An additional advantage is that the test can be performed with different materials: serum, plasma or a dried blood spot.

Masdiag laboratory participates in the international proficiency testing programme - Quality assurance in laboratory testing for IEM (ERNDIM).

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