Amino Acids In Food: Daily Value, Signs Of Deficiency

Amino acids: general characteristics, their classification and effect on the body

Amino acids are organic compounds whose molecules consist of amine and carboxyl groups. Amino acids are usually crystalline substances with a sweet taste, which can be obtained as a result of certain chemical reactions. Most amino acids come in two forms: L-isomers and D-isomers. Amino acids of the first type are found in nature and are extremely important for the health of the body. D-substances, in turn, are found in bacteria, play the role of neurotransmitters in the body of some mammals.

The human body is approximately 20% composed of proteins that perform many functions:

1. They are the main building material in the body - it is from proteins that muscles are built, proteins are necessary for the normal growth of hair, nails, and for skin regeneration.

2. They are carriers of vitamins, hormones, fatty acids, and other substances - the most striking example is the protein transferrin, which is a carrier of iron to the site of hemoglobin synthesis.

3. Proteins ensure the normal functioning of the immune system - without a sufficient level of protein in the body, there will be no strong immunity, since antibody proteins are actively involved in neutralizing foreign antigens of microorganisms.

4. They are catalysts for all biochemical metabolic reactions of the body - proteins accelerate the processes of synthesis and decay.

Amino acids are involved in almost all life processes, they are the very building blocks from which protein is built.

Interestingly, in nature, only plants and some microorganisms are able to synthesize all types of amino acids. But people (and animals) can only get some essential amino acids from food. Based on the ability to synthesize, these useful substances are divided into 2 groups:

• irreplaceable (the body receives only from food);

• interchangeable (synthesized in the human body due to metabolic transformations with the participation of intestinal bacteria).

Essential amino acids are: arginine, valine, histidine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, phenylalanine. Non-essential amino acids: alanine, asparagine, aspartate, glycine, glutamine, glutamate, proline, serine, tyrosine, cysteine. Despite the fact that the body is able to synthesize arginine and histidine, these amino acids are also among the essential ones, as there is often a need to supplement their reserves from food. Often these two amino acids are separated into a separate group of conditionally essential amino acids. The same can be said about tyrosine and cysteine, which can move from their group of essentials to the list of essentials if the body feels a lack of phenylalanine.

Let us consider in more detail each of the amino acids and its effect on the human body. Let's start with essential amino acids:

1. Leucine - is involved in the production of insulin, and is also a building material for muscles. In our body, leucine is found in the blood, glands and organs, it is indicated for muscle tissue dystrophy, it works well in the treatment of sarcopenia, exhaustion of the nervous system, and a decrease in hemoglobin.

2. Isoleucine - activates the growth of muscle tissue to a lesser extent, supplies them with glucose to a greater extent, participates in the synthesis of hemoglobin, biotin (vitamin B7) is needed for the absorption of isoleucine and leucine. Isoleucine also has the ability to increase exercise endurance.

3. Methionine - improves digestion and liver function. It is also necessary for the synthesis of taurine, serotonin, and is involved in the production of collagen. An excellent helper in the processing of fats. According to some reports, it alleviates the state of toxicosis in pregnant women. Methionine also promotes the removal of heavy metals from the body and reduces the effects of radiation exposure.

1. Phenylalanine - our brain uses it to synthesize norepinephrine, which in turn helps transmit signals from nerve cells to the brain. Important properties of this amino acid are: mood stabilization, suppression of unhealthy appetite, memory improvement, increased susceptibility. Phenylalanine helps relieve pain. However, there is one thing - an excess of this amino acid has a negative effect on the nervous system.

2. Tryptophan is the protector of our emotional well-being. The production of serotonin (the hormone of joy) directly depends on the intake of tryptophan. In addition, tryptophan acts as a relaxant on us: it normalizes sleep due to the fact that tryptophan is converted into melatonin (sleep hormone), helps to feel better, uplifting. Stabilizes appetite, positively affects the work of the heart and the condition of the arteries.

3. Threonine - helps the digestive system and gastrointestinal tract to function normally. Stimulates the protective functions of the body (immunity), helps in the formation of elastin and collagen. For the liver - this is an indispensable assistant, it does not allow fat to be deposited in the liver. However, excess threonine can lead to the accumulation of uric acid.

4. Lysine is an essential amino acid for us. Without it, normal absorption of calcium does not occur, it is involved in the synthesis of collagen, improves the condition of the hair. Men love lysine for its anabolic effect - an increase in muscle mass. Also, without lysine, the normal functioning of the immune system, the synthesis of many hormones and enzymes is impossible.

5. Valine - takes part in the protection of the myelin sheaths of nerves, saves from stress, is a kind of antidepressant, is effective in stimulating the growth of tissues and muscles, levels out sudden temperature changes in the environment.

The following group of amino acids are conditionally essential:

1. Arginine is an amino acid that is produced by the body of a healthy adult on its own, but in infants and the elderly, the synthesis of this substance is significantly reduced. Arginine acts as a growth stimulant in children and adolescents, and can also be indicated during pregnancy with a low fetal weight. The main function of arginine is its ability to increase the level of nitric oxide, i.e. it provides the flexibility of blood vessels, maintains their tone, improves blood circulation, which leads to a better supply of tissues and organs.

2. Histidine promotes the restoration of damaged tissues, the formation of leukocytes and erythrocytes, the construction of myelin sheaths of cells. This amino acid is necessary from birth to twenty-one years, as well as during periods of recovery after serious illnesses and injuries. Deficiency of histidine can provoke hearing problems, and excess - the development of neurosis and even psychosis.

Conditionally replaceable amino acids - cysteine ​​and tyrosine - are distinguished into a separate group, their synthesis is carried out in the presence of essential amino acids.

1. Cysteine ​​is produced in the body from the essential amino acid methionine and, if deficient, can also become an essential amino acid. Cysteine ​​is needed by the body to produce taurine, which regulates the functioning of the nervous system, and glutathione, which is responsible for the antioxidant defense of the body. Cysteine ​​is part of collagen, keratin, insulin, if necessary, can be transformed into glucose, filling the body with energy, regulates blood pressure, lowers cholesterol in the blood, and removes toxic substances from the body.

2. Tyrosine is produced in a healthy body from the essential amino acid phenylalanine. It regulates the synthesis of hormones of the thyroid gland, adrenal glands, pituitary gland. It improves thought processes, memory, helps to withstand stressful situations, and also maintains a good mood. Responsible for the production of melanin pigment, thanks to which we have one or another color of hair and skin. For athletes, it is also important that tyrosine, participating in protein synthesis, promotes the growth of muscle tissue, accelerates recovery after heavy physical exertion.

The content of essential amino acids in food

The best sources of essential amino acids are animal proteins. Scientists have long believed that only animal products contain the components necessary for humans to form protein. There was an opinion that only animal proteins can build the human body. But protein of plant origin cannot be as complete for a person. This claim has now been refuted. Studies by Swiss and German scientists gave the following results - plant foods also have a lot of protein, which is absorbed by the body. That is, if a person is a vegetarian, the diet can be made complete. To do this, you need to consume different types of protein plant foods daily. Thus, the absence of an amino acid in one product will be compensated by its presence in another.

What and who to eat is a personal choice for everyone. Below is a list of foods to look for essential amino acids.

1. Valine - this amino acid is found in animal products, dairy products, sour milk. There is a lot of valine in soy, in almost all grains, mushrooms and nuts, wheat germ, sesame seeds, hemp, chia. Valine is also found in fruits and vegetables such as spinach, broccoli, figs, avocados, apples, blueberries, cranberries, oranges, and apricots.

2. Histidine - found in cereals, rice, nuts (especially raw), soy and legumes. Eat animal foods, wheat germ, and you won't be deficient in histidine.

3. Isoleucine - any meat, fish and seafood, chicken eggs, milk and dairy products. From plant foods, isoleucine can be found in nuts - cashews and almonds, soybeans, most seeds, rye, lentils, wheat germ.

4. Leucine is found in meat, fish, dairy products, nuts, brown rice, peas, wheat germ, and sunflower seeds. Plant Sources: Watercress, pumpkin, seaweed, turnips, figs, avocados, raisins, dates, apples, blueberries, olives, and bananas.

    

5. Lysine - there is a lot of it in cheese, especially hard varieties. It is also found in all animal foods, in dairy products. From plant sources, it can be found in lentils, chickpeas, watercress, hemp and chia seeds, spirulina, parsley, avocados, almonds, and cashews.

6. Methionine - all dairy and sour-milk products, eggs, meat, cereals, cereals, sesame, nuts are rich in it. The brazil nut is the champion in methionine content. Plant sources: figs, onions, cocoa, kelp, raisins.

7. Threonine - found in all animal products, as well as in peas, pumpkin, greens, hemp seeds, sesame, sunflower and chia seeds, soybeans, almonds, avocados, figs, raisins, quinoa and wheat. Interestingly, spirulina and watercress contain more threonine than meat.

8. Tryptophan - can be found in meat, dairy and dairy products, fish, sesame seeds, dates, bananas and legumes.

9. Phenylalanine - sources are cheese, cottage cheese, milk, dried mushrooms - chanterelles, soy. Phenylalanine can also be found in animal food - this is any meat, chicken egg, fish and seafood.

A few words about conditionally essential amino acids, some of which we still need to get from food. So, tyrosine can be obtained by eating animal products, rice, leafy vegetables and peanuts. Cysteine ​​is found in meat, fish, soybeans, onions, red peppers, egg yolks.

Daily intake of amino acids

The need for amino acids increases in the following situations:

• for people professionally involved in sports, as well as during increased physical activity;

• during intensive mental work;

• during and after an illness;

• the correct balance of amino acids is important for children during the growth period.

The recommended daily intake of essential amino acids for an adult of the World Health Organization (mg per 1 kg of body weight):

• histidine - 10 mg;

• isoleucine - 20 mg;

• leucine - 39 mg;

• lysine - 30 mg;

• methionine - 15 mg;

• phenylalanine - 25 mg;

• tryptophan - 4 mg;

• valine - 26 mg.

At the same time, there are situations in which it is necessary to limit the intake of amino acids, for example, people with genetic diseases (in which the absorption of amino acids is impaired) should not exceed the recommended daily doses. Otherwise, protein foods can cause a change in the functioning of the gastrointestinal tract, allergies. In addition, diabetics, people with liver disease, or those suffering from certain enzyme deficiencies are at risk of developing an amino acid imbalance.

Signs of deficiency and excess of amino acids in the body

With a lack of amino acids, the body is forced, as it were, to "extract" them from its own reserves. This is especially noticeable and critical for athletes, as they seek to gain muscle mass, not lose it. In the absence of at least one essential amino acid, the process of synthesis of the body's own proteins is suspended. Therefore, there may be: muscle weakness, dysfunction of the nervous system, digestion, sleep, impaired immunity, increased blood sugar levels, depression and other signs of metabolic and energy pathology.

With injuries, stress, age-related changes, infections - a balanced diet is not enough. Additional intake of amino acids is required.

The following are more specific symptoms of a deficiency in some of the amino acids:

• Arginine - increased blood pressure, impaired brain activity, hormonal metabolism disorders, deterioration of sperm, decreased libido, premature aging, obesity.

• Valine - cracks in the mucous membranes, arthritis and arthrosis, memory impairment, weakened immunity, depressive mood, superficial sleep, muscular dystrophy (muscles become flabby, any tension causes pain), dryness of the mucous membranes of the eyes, temperature changes in the external environment cause a feeling of chills or heat ("I'm cold", "I'm hot").

   

• Methionine - liver damage, edema, brittle hair, delayed development of the fetus and newborn, malformations of the nervous system in children, severe mental disorders, the development of atherosclerosis.

• Phenylalanine - memory loss, Parkinson's disease, depression, chronic pain, muscle loss and sudden weight loss, hair bleaching, premenstrual syndrome.

• Tyrosine - obesity, fatigue, depression, poor stress resistance, mood swings, premenstrual pain, decreased appetite, decreased brain activity, manifestations of Parkinson's disease, impaired thyroid function, hyperreactivity, disorders of the adrenal glands.

• Isoleucine - severe headaches and dizziness, irritability and fatigue, weakened immunity, depression, muscular dystrophy, hypoglycemia.

An excess of amino acids, in turn, also leads to disturbances in the functioning of the body. Common signs of an excess of amino acids are as follows: thyroid disorders, joint diseases, hypertension.

You should be aware that such problems can arise if the body has a severe deficiency of vitamins A, E, C, group B, as well as a deficiency of selenium. In the case of the norm, the excess of organic compounds will be neutralized.

More specific symptoms of excess amino acids include the following:

• Arginine - urticaria, tremor of the limbs, irritability, turning into aggressiveness, lowering blood pressure.

• Valine - goosebumps, numbness, tingling in the limbs, problems with the gastrointestinal tract, irritability, allergic reactions.

• Methionine - allergic reactions, nausea and vomiting, a feeling of drowsiness. By the way, pregnant women should not take methionine without consulting their doctor, as it increases the production of estrogen.

• Phenylalanine - overexcitation of the nervous system, memory loss and a general disruption of the nervous system.

• Tyrosine - a drop in muscle mass, a manifestation of hypertension, reduced body temperature, increased heart rate.

• Isoleucine - thickening of the blood, an increase in the concentration of ammonia and free radicals in the body, apathy, allergic reactions.

How to get amino acids

From the foregoing, it is clear that it is possible to control the intake of amino acids with the help of nutrition, but sometimes situations still arise when an additional intake of amino acid complexes is necessary. It's about sports. Especially if we are talking about professional sports. Here, athletes often apply for additional complexes, not relying only on food.

For example, for successful muscle building in bodybuilding, amino acid complexes consisting of leucine isoleucine and valine are often used. To maintain energy during training, athletes use methionine, glycine and arginine, or products containing them, as nutritional supplements. But, all this will be useless if you do not eat foods that are rich in amino acids. It is an important part of an active and fulfilling lifestyle. Include quality meats, fish, seafood, dairy products in your diet, provided they are well tolerated, supplement all this with plant sources of amino acids (legumes, cereals, grains, nuts and seeds) and you will never experience problems with deficiency or excess of amino acids.

Summing up, we can say that the content of amino acids in food products can satisfy the need for them for the whole organism. Not counting professional sports, when the muscles are under tremendous stress, and they need additional help.