Are amino acids proteins? How many amino acids do humans need? What is the difference between animal properties and plant-based protein?

Protein and amino acids

amino acid combinations have different functions such as cells or enzymes

Protein is a substance composed of many amino acids, and is the substance with the largest content of human body except water.

says that there are about five hundred amino acids in nature, of which only twenty amino acids can be constructed in adults. These twenty amino acids can produce 50,000 to 100,000 proteins in humans. In other words, as long as a certain amino acid is missing, the protein required for humans cannot be produced. Among these twenty amino acids, eleven of them can be synthesized in the necessary amounts, called "non-essential amino acids". However, there are nine types of synthesis acids that cannot be synthesized in the body or have poor synthesis efficiency, and there are nine types of synthesis acids that can be synthesized but have insufficient necessary amounts. They must be taken from food as "essential amino acids". Generally speaking, people with normal dietary habits rarely need to worry about lacking these amino acids, but people who often adopt extreme fat loss methods or partial diet should pay special attention.

Protein is repeatedly decomposed and synthesized in the body to sustain life-saving operations. In addition to creating body structures such as muscles or skin, it can also produce anti-grafting materials such as enzymes or immunoglobulins, or hormones that can adjust their function, which is closely related to the physiological function of the human body.

Digestation and absorption of protein

Dissolve into amino acids through digestive enzymes and absorb the proteins in the food. After chewing and shaving to a certain size, it is swallowed and eaten.

The protein entering the stomach is broken down into polypeptides from gastric juice with salt acid as the main component and pepsin in gastric juice.

Next, enter the twelve fingers and decompose it into oligopeptides by digestive enzymes such as trypsin, chymotrypsin, elastic protease, carboxypeptidase, etc. in the pancreatic juice.

Finally, in the kidney, digestive enzymes such as aminopeptidase or dipeptidase secreted by the microporous hairs of epithelial cells are decomposed into the smallest single amino acid, or dipeptides formed by two amino acids. In this way, after being absorbed by the micro hairs of epithelial cells, they are all turned into the smallest single amino acids, and are sent from the microvascular channel to the liver, and then sent to various tissues throughout the body.

Protein

can be used as a biological synthetic component or source of heat, and after food is collected, the amino acids decomposed by digestion and absorption will be mixed and dissolved by the proteins of the body that form muscles or internal organs, and are mixed and dissolved in the liver or blood, etc., called "amino acid reproduction pool". After that, the amino acids are sent to the whole body to synthesize new body proteins or enzymes, hormones, immune anti-body and other substances. The mechanism of repetitive decomposition and synthesis of proteins is called "transformation and update"; its update rate is related to the year, and the larger the year, the slower the update rate. Furthermore, the renewal rate of different organizations is also different. For example, the protein in the blood or liver is about twenty days, and half of the protein will be renewed, and the protein in the muscle will take half a year and half a year before it will be renewed.

The unused amino acids during the synthesis are decomposed and cleaved into amine groups and α-ketoacid (transaminogen reaction). The nitrogen-containing amine groups form ammonia (oxidation of amine groups), which is circulated into urea through urea, becoming excreted from the urine. The remaining α-ketolic acid is not only sent to the citric acid cycle (TCA cycle) as a heat source, but also as a material for synthesizing fatty acids or glucose.

Replacement and update

About 1~2% of the body's protein will be updated every day

Organs in the body must regenerate the organization by replacing the protein. The update rate varies depending on the protein type. For example, red blood cells are about 120 days, liver is about 20 days, muscles are about 180 days, and half of them will be updated.

In addition, protein can also be used as a source of heat, but when the blood sugar in the body is very sufficient and there is no need to break down protein as a heat, sometimes unused residual protein can be cleared from the body.

Animal properties and plant-based protein

Protein quality are different from animal properties and plant-based foods

Protein-rich foods include animal properties such as fish, meat and eggs, as well as plant-based proteins such as beans or grains. The content of these two types of essential amino acids is different. Most animal proteins contain sufficient nine essential amino acids, but the content of essential amino acids in plant proteins is insufficient. The "Amino Acid Rating" below uses a bucket to compare the balance state of these nine essential amino acids. The numerical value of essential amino acids depends on how these amino acids are used in the body.

Among the nine amino acids, as long as one of them has a low value, the number of other eight types that can be used will also be small. This low-value amino acid is called the "first restricted amino acid", but as long as foods rich in other insufficient amino acids are taken, the amino acid score can be improved.

The maximum value of the design score is 100. Even if the value exceeds 100, the amino acid score is still marked as 100.

In addition to this kind of amino acid rating, the latest indicators such as "PDCAAS" (protein digestibility correction amino acid rating, the proportion of actual digestion and absorption in the body can be converted into chemical evaluation), "DIAAS" (digestable essential acine acid rating) and other latest indicators.

Amino acid rating

9 plates framed into buckets are used as 9 amino acids, and only one is not enough, and the water inside cannot be retained. Chart the equilibrium state of these amino acids. We can replenish the lack of amino acids through other ingredients we eat daily, or confirm whether they can become high-quality protein.

Animal protein

Take chicken eggs as an example, the protein content of 100 g of the edible part is 12.3 g.

The protein content of a chicken egg is about 6.2g, which can provide about 10% of the protein intake per day for adults..

Plant protein

In plant-based foods, soybeans have a high protein content, a low fat content, and are rich in dietary fibers. Compared with animal foods, plant-based protein absorption rate is slow and requires more time to digest, which is beneficial to weight loss. In order to balance amino acids, rice and fish can be eaten together to supplement the necessary amounts of soy protein in a limited amount of "thiominic acid" (methiamine, cystic acid).

※ This article is excerpted from "The Nutrition Collection of NHK, Japan, to Create a Healthy Daily".

"Collection of Nutrition from NHK, Japan to Create a Healthy Day"

Author: Kaminichihiro, Fujii Yoshida Sohiro

Translator: Gao Shuzhen

Publisher: Ark Culture

Publication date: 2023/09/20

Responsible editor: Gu Zihuan