How to reasonably intake amino acids from food?

Amino acid is a class of organic compounds containing amino and carboxyl groups, and the chemical formula is RCHNH2COOH. Amino Acids are one of the many biologically active macromolecules that constitute the organism, and are the basic materials for building cells and repairing tissues. It is used by the human body to make antibody proteins, hemoglobin, enzymes and hormones to maintain and regulate metabolism.

Types of amino acids

There are more than 100 known amino acids isolated from various natural sources, but there are only more than 20 kinds of amino acids that constitute human protein. In order to meet the needs of human metabolism, people must take the amino acids needed from food.

 Among the more than 20 kinds of amino acids that make up human proteins, most of them can be directly synthesized in the human body or converted from other amino acids, called non-essential amino acids; a few humans cannot synthesize or synthesize slowly, which cannot satisfy the body's metabolism.

The needs of food must be supplied by protein in food. These amino acids are called essential amino acids. There are 8 essential amino acids, namely, Lysine, threonine, leucine, isoleucine, valine, and methionine. Acid (methionine), tryptophan, phenylalanine; in addition, the amount of arginine and histidine synthesized by the human body does not meet its own needs, and some of it needs to be taken from food, which we call the human body semi-essential amino acids.

The role of amino acids

Amino acids are the constituents of protein, which play an important role in human nutrition and physiology. People's demand for protein is actually the need for amino acids. The protein we ingest from food every day is 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 small intestinal mucosa.

Its role is mainly manifested in the following five aspects:

　　One is to synthesize or repair tissue proteins to supplement similar proteins that are broken down in the body's metabolism

The second is to synthesize or convert into other amino acids, such as phenylalanine can be converted into tyrosine, methionine can be synthesized into cysteine, etc.

Three is the catabolic process of amino acids, and the nitrogen-containing part is usually converted into urea

　　Four are nitrogen-containing compounds other than the synthesized protein, such as purine, creatine, etc.

　　Five is used as a heat-generating nutrient, which releases energy during metabolism for the body's needs.

　　Reasonable diet, maintain the proper proportion of amino acids in the diet

The Food and Agriculture Organization of the United Nations stipulates that the proportions of 8 essential amino acids are: leucine 17.2%, isoleucine 12.9%, valine 14.1%, lysine 12.5%, threonine 10%, methionine 10.7%, Phenylalanine 19.5%, tryptophan 3.1%.

In nutrition, proteins with higher nutritional value and amino acid composition in proportion to the requirements of 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, the one essential amino acid with the most insufficiency is called the restricted amino acid of the food. If the content of more than two kinds of amino acids is insufficient, it is called in turn according to the degree of deficiency.

It is the first restricted amino acid, the second restricted amino acid, the third restricted amino acid, etc.

Too much or too little of any kind of essential amino acid in 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. In the long term, it can affect the physiological function of the body and cause Metabolic disorders, decreased body resistance, etc.

For example, lysine can enhance gastric juice secretion, increase protein utilization, enhance hematopoietic function, and enhance disease resistance. Because lysine is the first limiting amino acid of cereal protein, such as long-term simple consumption of cereals, it will inevitably cause The lack of lysine required by the human body leads to loss of appetite, metabolic disorders, decreased activity of various enzymes in the body, impaired hematopoietic function and other symptoms, as well as anemia, edema, muscle atrophy, weight loss, and premature aging.

As a result of menstrual disorders, children will experience poor growth, mental retardation, and decreased disease resistance. Another example is methionine. In addition to forming human protein with other amino acids, methionine has a variety of special functions. If the human body lacks methionine, fatty liver, liver necrosis, and lecithin deficiency will occur; For example, tryptophan, the human body can use it to synthesize niacin, which is VB5, which is needed by the human body, and mangy is often related to VB5. If corn is the staple food for a long time, it is easy to produce mangy. This is because the tryptophan in corn or the content of VB5 is less.

In addition, tryptophan is the premise of the neurotransmitter serotonin, which is related to human sleep, and MILK contains more tryptophan, so drinking a glass of milk before going to bed at night will help you sleep and help treat insomnia. 

　　In the diet, it is necessary to fully consider the composition and balance of amino acids. It is not allowed to eat foods containing certain fortified amino acids in large quantities regularly, nor to eat foods containing certain restricted amino acids. we suggest:

1. Reasonable adjustment of diet

Using the complementary effect of protein, that is, mixing several kinds of foods, combining meat and vegetables, combining thickness, and complementing each other to improve the utilization value of protein. For example, legume protein has higher lysine, but for cereals, it is the first restricted amino acid. If legumes and cereals are mixed and eaten in an appropriate ratio, they can take advantage of their respective advantages. 

2. Eat foods fortified with essential amino acids appropriately

When strengthening, it should be strengthened in the order of the first, second, and third restricted amino acids, otherwise it will be useless and the opposite result will be obtained. For example, adding 0.2% lysine and 0.1% threonine to rice will increase the potency of the protein from 1.5 to 2.6, and the digestibility of the protein from 50% to 70%, which is close to that of animal protein. level. Another example is the addition of 0.5% methionine to soybeans to make the nutritional value of protein equivalent to the level of meat, milk, and eggs.

3. Eat some whole protein foods with high nutritional value in moderation

Because the whole protein food contains all kinds of essential amino acids in a large amount, and the proportion is right, it is suitable for human needs, so it is also called high-quality protein, such as milk, eggs, meat (lean meat), soybeans and fish.