compose:
Liu Yaping, Food R&D Engineer, Chongqing Sanpin Functional Food Research Institute
Li Zhong, Chief Health Science Expert of Chongqing Municipality (Medical Nutrition, Food Science, Food Testing) Vice President of Chongqing Natural Health Therapy Research Association
Reviewer: Xiong Dandan, National Senior Dietitian, Registered Nutrition Technician, Director of Nutrition Teaching and Research Office, Chongqing Sanpin Functional Food Research Institute
Proteins are an important material basis for life and the body, and are a major class of substances that express biological genetic traits. It is widely distributed in the human body, with a high content, accounting for about 16%-20% of the total mass of the human body, and is closely related to life activities.
It can be seen that protein is so important, so do you really understand it?
1
What is protein?
Protein is one of the important components that make up the human body, and all cells in the human body contain protein. The vast majority of proteins consist of 20 amino acids. Amino acids are divided into essential amino acids, semi-essential amino acids, non-essential amino acids, essential amino acids refer to amino acids that the human body cannot synthesize or synthesize fast enough, and must be supplied by food. What can be synthesized in the body is called non-essential amino acids. There are 9 kinds of essential amino acids known to the human body, including isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and histidine. And the composition ratio of various essential amino acids is called the amino acid pattern.
2
Physiological role of proteins
Constructs and repairs tissues and organs
Any tissue and organ in the human body is composed of proteins as important substances (including muscle tissue, bones, teeth, nails, liquid blood, etc.). Therefore, the human body needs protein for growth, and metabolism needs protein. The body has 3% of proteins that are metabolically renewed every day. Protein is required for repair after injury, etc. Protein is very important for the growth and development of the human body.
Constitutes a physiologically active substance in the body
Important substances in the human body such as enzymes, hormones, hemoglobin, myoflocoagin, antibodies, etc. are all based on proteins. These substances play an important role in water and salt metabolism, acid-base balance, colloidal penetration, etc. In addition, the formation of vision, the coagulation of blood, and the movement of the human body are all related to proteins.
Supply energy
Supplying energy is a secondary function of proteins. But only when the body's energy supply is severely insufficient, proteins are metabolized and broken down, releasing energy. Each 1g of food protein provides 16.74 KJ (4.0 kcal) of energy, and 10%-15% of the daily energy needed by the human body is provided by protein.
Special physiological functions of peptides
Peptide is an organic compound, made of amino acid dehydration, containing hydroxyl and amino groups, is a sexual compound, more than 50 amino acid residues composed of polypeptide can be called protein. Some active peptides that are absorbed directly from the intestine into the bloodstream have special physiological functions. Participates in the body's immune regulation, promotes mineral absorption, lowers blood pressure, and scaves free radicals.
3
The harm of insufficient and excessive protein intake
Inadequate protein intake:
Protein deficiency is often accompanied by energy deficiency, leading to protein-energy malnutrition (PEM), and clinical features can be divided into dry lean, puffy, and mixed types. Protein deficiency is detrimental to all organs, especially in infants and children PEM can have long-term adverse effects on brain function. Protein deficiency in adults is mainly manifested as tiredness, weight loss, anemia, decreased immunity and stress ability, and memory loss.
Excessive protein intake:
The impact of excessive protein intake on the health of the body has been controversial, resulting in countries that have not yet established the maximum protein tolerable intake. There are some studies that superficially increase the risk of kidney stones by ingesting high animal eggs, but there is no clear conclusion so far. For adults, the WHO considers double the recommended intake to be a safer upper limit, although some people do not experience harmful symptoms when they consume 3 to 4 times the recommended intake of protein, but do not recommend that people consume protein too high for a long time.
4
Recommended Dietary Protein Intake for Chinese Residents (g/d)
<col>
Age (years)/physiological stage
Average demand
Recommended intake
man
woman
0-
-
9(AI)
0.5-
15
20
1-
25
4-
30
7-
40
11-
50
45
60
55
14-
75
18-
65
50-
65-
80-
Pregnant women (medium)
+10
Pregnant women (late)
wet nurse
Note: AI indicates the appropriate intake.
5
The main food source of protein
There is so much protein, but not all proteins can be absorbed and utilized by the human body, so we have to consume high-quality protein to be more conducive to our health.
High-quality protein means that the amino acid pattern is close to the amino acid pattern of the human body, and the utilization rate of essential amino acids in the body is high. The amino acid pattern of egg protein is closest to the amino acid pattern of the human body, which is called the reference protein.
Top 10 High Quality Protein Foods
serial number
food
Protein content g/100g
Amino acid score (representative value)
Egg
13.1
106
Milk
3.3
98
fish
15-22
Shrimp meat
16-23
91
chicken
20.3
6
Duck meat
15.5
90
7
Lean beef
22.6
94
8
Lean lamb
20.5
9
Lean pork
20.7
92
soybean
35
63 (Soy Protein Concentrate 104)
Note: The higher the amino acid score, the better the protein quality, and the easier it is for the body to absorb and utilize.
In addition to the top ten high-quality proteins, there are many foods that are also high in protein, mainly meat, milk and dairy products, fish, shrimp and seafood, and dried legumes and grains, which are less abundant in rhizomes and green leafy vegetables.
Protein content in various foods (g/100g)
Milk and dairy products
Nuts
content
Milk tofu (fresh)
46.2
Peanut kernels (raw)
24.8
Sour egg
40.4
almond
22.5
Qula
39.1
Walnuts (dried)
14.9
cheese
25.7
Walnuts (fresh)
12.8
Milk tablets
13.3
jackfruit
4.9
Cheese (full cheese)
8.6
coconut
Fresh camel milk
3.7
Sour spines
2.8
Fresh milk (representative value, full fat)
3.4
Durian
2.6
Pure milk (representative value, full fat)
Mulberry (representative value)
1.7
yoghurt
3.2
Yellow peel fruit
1.6
Sheep's milk
1.5
Pomegranate (representative value)
1.3
butter
longan
1.2
butter
1.4
human milk
Dates (fresh)
1.1
Meat
Camel hooves
25.6
venison
19.7
sausage
22
Donkey meat (lean)
21.5
goose
17.9
Chicken (represented value)
Dog meat
16.8
quail
20.2
pigeon
16.5
horsemeat
20.1
Duck (represented value)
Turkey leg meat
Pigeons
11.3
Rabbit meat
Mushrooms
Eggs
Hair vegetables (dried)
Hairy eggs
14.2
Shiitake mushrooms (dried)
Eggs (representative value)
Fungus (dry)
12.1
Quail eggs
White fungus (dry)
Sea duck eggs
12.7
straw mushroom
2.7
Duck eggs
12.6
Enoki mushroom (fresh)
2.4
Goose eggs
11.1
Shiitake mushrooms (fresh)
2.2
oyster mushroom
king oyster mushroom
Kelp (fresh)
Fish, shrimp and seafood
Shrimp
43.7
fish
17.6
Ding Gui fish
29.7
Eels
17.5
Pincer fish
29.2
Crab
Ya fish
26.5
Squid (fresh)
17.4
Bonefish
25.8
Catfish
17.3
Green shrimp
23.8
Yellowtail
sturgeon
23.4
White rice shrimp
Sharp-mouthed white
22.7
Whitebait
17.2
herring
crucian
17.1
Mandarin fish
19.9
White striped fish (naked fish)
16.6
sardine
19.8
Grass carp
Verbal fish
19.6
trepang
lobster
18.9
portunid
15.9
Conger
18.8
Snail (representative value)
15.7
Golden pomfret
18.7
Salmon
15.6
eel
18.6
Fathead fish
15.3
Red trout
Catfish
14.8
sea bass
Turn back to the fish
14.5
mullet
18.5
mackerel
14.4
Tilapia
18.4
Chibei
13.9
Mud carp
Sea crabs
13.8
Bream
18.3
abalone
Red-eyed trout
18.1
Mussels (fresh)
11.4
Red bass (fresh)
Scallops (fresh)
Yellow eel
18.0
Sea mussels
10.9
loach
Oysters
silver carp
17.8
Clams (representative value)
10.1
hairtail
17.7
Clams
7.3
carp
oysters
5.3
Vegetables
Wattle beans (dried)
43.6
Corn (fresh)
Black beans (dried)
36.0
Golden loofah
Amaranth (green, fresh)
Green beans (dried)
34.5
Lentils (fresh)
soybean
33.1
Milk cabbage
Lentils (dried)
25.3
Chicken feathers
Mung bean (dried)
21.6
potato
Fava beans (dried)
Beans
2.5
Peas (dried)
Hollandaise beans
Red adzuki beans (dried)
Fennel (fresh)
Yellow cauliflower
19.4
leek
Cowpea (dried)
19.3
cassava
2.1
Flower beans (dried, red)
19.1
Summer (Fresh)
Edamame (fresh)
kohlrabi
1.9
Barley
Baby cabbage
wheat
11.9
Coriander (fresh)
1.8
Sorghum rice
10.4
Mung bean sprouts
barley
10.2
spring onion
Black rice
9.4
Chinese cabbage (representative value)
buckwheat
9.3
Chinese cabbage
millet
loofah
Broad beans (fresh)
8.8
rapeseed
highland barley
8.1
Eggplant (representative value)
Rice (representative value)
7.9
Onion (fresh)
brown rice
7.7
carrot
Indica rice
7.5
Bitter melon (fresh)
bibliography:
Chinese Nutrition Society. Reference intake of dietary nutrients for Chinese residents. Beijing:Science Press,2014.]
Wang Xueyan,Shi Wenzhao. Protein Chemistry and Its Applications. Beijing:China Textile Publishing House,2016.]
Hu Min. Clinical Medicine Nutrition. Beijing:Chemical Industry Press,2018.]
Yang Yuexin et al. Chinese Food Composition Table (6th Edition) Volume 1/Volume 2. Beijing:Peking University Medical Press.2018.
Yang Yuexin,Ge Keyou. Encyclopedia of Chinese Nutrition Sciences (Part 1).Beijing:People's Medical Publishing House.2020.]