The main sources of protein are meat, eggs, milk and legumes. Generally speaking, protein from animals is of high quality and contains sufficient essential amino acids. There are about 8 kinds of essential amino acids, which can't be synthesized by human body, but must be ingested from food. If there is a shortage of essential amino acids in the body, it is impossible to synthesize enough protein for all tissues of the body, and other excess protein will be wasted by body metabolism, so it is very important to ensure adequate intake of essential amino acids.
1. Soybean and soybean products
Soybeans include soybeans, black soybeans and green soybeans. Soybean is rich in high-quality protein, which can replace "meat". When you don't prepare meat, fish and other meat dishes, remember to order some soybeans or bean products. Soybean and bean products are also rich in calcium and potassium, as well as a variety of functional substances such as soybean isoflavones and phytosterols; Bean products contain no cholesterol and little saturated fat. People who usually eat more meat suggest that bean products should be used instead of meat, which has many benefits for cardiovascular health.
It is recommended to eat about 25g soybeans every day. 25g soybean ≈70g north tofu ≈ 140g south tofu ≈60g dried tofu.
2. Fish and shrimp
The protein content and quality of aquatic products such as fish and shrimp are very high, and the muscle fibers of fish are thin and short, which is easy to digest. You can add some fish and shrimp when cooking porridge and noodles. Fish is also rich in w-3 polyunsaturated fatty acids, and ω-3 can alleviate and inhibit inflammation. Shellfish seafood is also rich in zinc, which is also very important to the immune system. Zinc can also increase the number and activity of T cells. Studies have shown that vitamin C and zinc supplementation can enhance the antibody level in patients.
It is recommended that ordinary adults eat fish twice a week or 300~500 grams.
Step 3: eggs
Cooked eggs can be said to be one of the most nutritious foods. Small eggshells contain all the nutrients needed to hatch chickens. Eggs have high protein content and complete nutrition. Besides B vitamins, vitamin A, vitamin D, calcium, zinc and other minerals, there are lutein which is very important for eyes.
The average adult should eat an egg every day, both yolk and protein, because most of the nutrients are in the yolk; Older people with normal blood lipids can appropriately increase eggs.
4. Dairy products
The main component of milk is water. The protein content is not high (3.5%), but it is convenient to drink, and it is easy to drink hundreds of milliliters. At the same time, milk is an irreplaceable good source of calcium in natural foods. For people who need energy supplement but have a small appetite, the nutritional density of food can be increased by adding milk or milk powder to other foods. For example, cook porridge with milk and steam egg soup.
Dietary Guidelines for China Residents suggest drinking 300-500ml of milk every day. Liquid milk, milk powder, yogurt, cheese, etc.
5. Livestock and poultry meat
Livestock meat-pig beef and mutton belongs to "red meat" in nutrition. All kinds of red meat have similar nutritional value, and are rich in high-quality protein, zinc, iron and other minerals, and are also good sources of B vitamins, especially pork. In contrast, "white meat" mainly refers to poultry meat such as chicken, duck and goose. Compared with red meat, white meat is generally lower in heme iron and fat prevention, lower in saturated fat, but also high in high-quality protein. It is recommended to eat with pig, beef and mutton instead.
Adults are recommended to eat 300-500g of livestock meat every week, with an average of 40-70g per day.