Amino acids (amino acids) are a class of organic compounds containing amino and carboxyl groups, with the chemical formula RCHNH2COOH.Amino acids are one of the many biologically active macromolecules that make up living organisms, and they are the basic materials for building cells and repairing tissues. It is used by the body to make antibody proteins, hemoglobin, enzymes and hormones to maintain and regulate metabolism.

Types of Amino Acids

There are more than 100 kinds of known amino acids isolated from various natural sources, but there are only 20 kinds of amino acids constituting human proteins. In order to adapt to the needs of human metabolism, people must take the amino acids required by the human body from food.

In the composition of human proteins in more than 20 kinds of amino acids, most of which can be synthesized directly in the body or from other amino acid transformation, known as non-essential amino acids;

A small number of the human body can not be synthesized or synthesized at a slower rate to meet the needs of human metabolism, must be supplied by the protein in the food, this type of amino acid is called essential amino acids, essential amino acids, there are eight kinds of amino acids, namely, lysine, threonine, leucine, isoleucine, valine, methionine (methionine), tryptophan, phenylalanine;

In addition, the amount of arginine and histidine synthesized by the human body does not satisfy its own needs, and it is necessary to take some of them from food, which we call semi-essential amino acids.

Role of Amino Acids

Amino acids are the components of proteins, which play an important role in human nutrition and physiology, and people’s demand for proteins is actually the demand for amino acids.

The proteins we take from food every day are finally broken down into amino acids in the gastrointestinal tract through the action of enzymes such as pepsin, trypsin, chymotrypsin and carboxypeptidase, and then absorbed by the epithelial cells of the mucosa of the small intestine.

Its role is mainly manifested in the following five aspects:

One is to synthesize or repair tissue proteins to replenish the same kind of proteins that are broken down in human metabolism;

The second is to synthesize or transform into other amino acids, such as phenylalanine can be transformed into tyrosine, methionine can be synthesized into cysteine and so on;

Third, into the catabolic process of amino acids, the nitrogen-containing part of which is usually converted into urea;

Fourth, it is synthesized into nitrogenous compounds other than proteins, such as purines and creatine;

Fifth, as a thermogenic nutrient, in the metabolic process to release energy for the body needs.

Reasonable diet, maintain the appropriate composition of amino acids in the diet ratio

According to the Food and Agriculture Organization of the United Nations (FAO), the ratio of the eight essential amino acids is as follows: leucine 17.2%, isoleucine 12.9%, valine 14.1%, lysine 12.5%, threonine 10%, methionine 10.7%, phenylalanine 19.5% and tryptophan 3.1%.

In nutritional science, proteins with higher nutritional value and amino acid composition that matches the proportion required by the human body are usually referred to as reference proteins.

If the amino acid composition of a certain food is compared with the reference protein, one of the essential amino acids with the most insufficient content is called the limiting amino acid of the food, and if there are more than two kinds of insufficient content, then the degree of insufficiency is called the first limiting amino acid, the second limiting amino acid, the third limiting amino acid and so on, in the order of magnitude.

Too much or too little of any essential amino acid in the food will cause a new imbalance between the amino acids needed by the human body, and even produce a negative nitrogen balance in the body, which in the long run can affect the physiological functions of the body, lead to metabolic disorders, and decrease the resistance of the body, etc. Lysine, for example, has the function of enhancing the gastric juice.

Lysine, for example, has the effect of enhancing gastric secretion, improving protein utilization, enhancing hematopoietic function, and strengthening the ability to fight diseases. Because lysine is the first limiting amino acid of cereal protein, such as long-term simple consumption of cereal food will inevitably result in a lack of lysine required by the human body, leading to loss of appetite, metabolic disorders, a variety of enzymes in the body to reduce the activity of the hematopoietic function by the obstacles and other symptoms to anemia, swelling, muscle atrophy, and other symptoms of the body. Anemia, swelling, muscle atrophy, weight loss and premature aging, for example, women will cause menstrual disorders, children will be stunted, mental retardation, reduced resistance to disease, and so on.

Another example is methionine, methionine and other amino acids in addition to the composition of human proteins, there are a variety of special functions, the human body lacks methionine, there will be a fatty liver, liver necrosis, lecithin deficiency and other phenomena; another example is tryptophan, the human body can be used to synthesize niacin that is the human body needs VB5, mange is often associated with VB5, long term corn-based food, easy to produce mange, this is because of corn The content of tryptophan or VB5 is less.

In addition, tryptophan is the premise of neurotransmitter 5-hydroxytryptophan, which is related to human sleep, and milk contains more tryptophan, so drink a cup of milk before going to bed at night, which will help you to sleep, and it has the role of assisting in the treatment of insomnia.

The composition and balance of amino acids must be taken into full consideration in the diet, and it is not possible to consume large quantities of food containing a certain kind of fortified amino acids or food containing a certain kind of restricted amino acids. We suggest:

1. Reasonable dietary adjustment

Make use of the complementary effect of protein, i.e., mixing several kinds of food, combining meat and vegetables, and combining coarse and fine food, so as to make up for the shortcomings and improve the utilization value of protein.

For example, the lysine of bean proteins is high, but for cereals, it is the first limiting amino acid. If beans and cereals are mixed and consumed in the right proportion, the respective advantages can be brought into play, and their nutritional value is comparable to that of beef.

2. Appropriate consumption of foods fortified with essential amino acids

When fortifying, it should be done in the order of the first, second and third limiting amino acids, otherwise it will not be beneficial, but will get the opposite result.

For example, if 0.2% lysine and 0.1% threonine are added to rice, the potency of protein is increased from 1.5 to 2.6, and the digestibility of protein is increased from 50% to 70%, which is close to the level of animal protein. Another example is the addition of 0.5% methionine to soybeans, which can make the nutritional value of protein equal to the level of meat, milk and eggs.

3. Moderate consumption of some high nutritional value of the whole protein foods

Because the whole protein food contains essential amino acids all kinds of full, more, the proportion of each other is appropriate, suitable for human needs, so it is also known as high-quality protein, such as dairy, eggs, meat (lean meat), soybeans and fish belong to the whole protein food.