One way to fix nitrogen is to use rhizobia from plants. Rhizobia is a kind of bacteria that can form nodules in the roots of leguminous plants. Under natural conditions, it can transform nitrogen in the air into nitrogen-containing compounds for plants to use. This is the truth that "growing beans is not fat, but growing them for a few years is fatter".

Protein is a complex nitrogen-containing organic compound with a large molecular weight, most of which is tens of thousands to millions, and the long axis of the molecule is as long as 1 ~ 100 um. They are connected by 20 amino acids through amide bonds ... Generally, the nitrogen content in protein is 16%, that is, 1 nitrogen is equivalent to 6.25 parts of protein, that is, 6.25 parts. ...

Among animal proteins, protein of milk and eggs is the best among all foods in protein, because it is the easiest to digest and has complete amino acids, so it is not easy to cause gout attacks.

The protein content of egg yolk is slightly higher than that of protein, but an egg yolk can contain as much as 300 mg of cholesterol. Even people without heart disease should not eat more egg yolk. protein's cholesterol content is 0; Egg yolk contains a lot of oil. Usually, we don't see oil in the egg yolk, but when you bake the egg yolk in the microwave oven, you will find that a lot of oil can flow out. You can also see the oil in the salted egg yolk. The calorie of egg yolk is six times that of protein, so egg yolk is also a high-calorie food, and it is a food that people who need to lose weight need to go on a diet.

Milk not only supplements protein, but also provides abundant calcium, which can prevent calcium deficiency. Skim milk powder has the highest calcium content and almost no fat, so milk made from skim milk powder is the best protein and calcium source for adults to keep slim.

The best vegetable protein is soybean protein, which contains 35% protein and is easy to absorb. Therefore, soy protein has always been the main source of protein for vegetarians. Bean products can lower cholesterol and fight cancer. Soybean protein is rich in isoflavones, which are hormone-like compounds that can inhibit the growth of tumor cells caused by hormone imbalance. Besides, edible fungi are the main source of protein for slimming people.

There is 20g protein per100g sesame sauce, which is higher than protein in lean pork, eggs, small yellow croaker and pomfret.

nitrogen equilibrium

Protein is decomposed into amino acids and small peptides in the digestive tract and absorbed. Most of them are used to synthesize tissue proteins, repair and grow damaged muscle tissues after exercise, and some of them are also used to synthesize various functional proteins and nitrogen-containing compounds other than protein, such as purine and creatine. After some amino acids are absorbed, they are decomposed in the body for energy supply.

Under the condition that the body does not ingest protein at all, protein in the body is still being decomposed and synthesized. An adult man weighing 60 kilograms still excretes 3.2 grams of nitrogen from urine, feces, skin and secretions every day, which is equivalent to 20 grams of protein. This inevitable consumption of nitrogen without intake of protein is called "necessary nitrogen loss". In other words, an adult male weighing 60kg should consume at least 20g of high-quality protein every day. Maintain normal protein metabolism in the body.

In a certain period of time, the relationship between nitrogen intake and nitrogen excretion is called "nitrogen balance", which is used to measure the protein requirement of human body and evaluate the protein status of human muscles.

There are three situations of nitrogen balance:

1, nitrogen balance: in a certain period of time, the amount of nitrogen taken in is equal to the amount of nitrogen discharged. It means that the synthesis and decomposition of protein in human body are in a balanced state, and the muscle circumference of human body is in the original circumference and level.

2. Positive nitrogen balance: the intake of nitrogen is greater than the discharge of nitrogen, and the synthesis of protein is greater than the decomposition, so the damaged muscle fibers will be quickly repaired and increased after exercise. Muscles are in a state of decline.

3. Negative nitrogen balance: nitrogen intake is less than nitrogen elimination, and protein synthesis is less than decomposition. At this time, the muscle protein of human body provides energy for the decomposition of physical activities.