protein
The closer the proportion of various essential amino acids in food protein is to the composition of protein, the easier it is to be digested and absorbed by human body to synthesize protein, and the higher its nutritional value. Animal protein is close to human protein in the proportion of various essential amino acids, so it is a high-quality protein. For example, milk, eggs and meat are all foods with high nutritional value because of their high protein content and easy digestion, absorption and utilization. In the third trimester, the uterus, breast and placenta of the mother are enlarged, and protein needs to store about 375g, which is the most storage period. The fetal weight increased from1000g at 28 weeks to about 3000g at 40 weeks, and the storage period in protein was also the longest. Therefore, the supply of protein in the third trimester should be increased by 25g every day on the original basis.
oil
Lipids include fats and lipids.
Fat mainly gives human body heat energy, and lipids are composed of various tissues and cells, among which phospholipids are indispensable substances for infant brain development. Fat-soluble vitamins A, D, E and K can be dissolved in fat and absorbed by human body to meet the needs of these vitamins.
The nutritional value of fat is related to the kinds of fatty acids it contains. Fatty acids are divided into saturated fatty acids and unsaturated fatty acids.
Linoleic acid, linolenic acid and arachidonic acid are all unsaturated fatty acids that cannot be synthesized by human body, and can only be supplied through food, also known as essential fatty acids. Essential fatty acids mainly exist in vegetable oil, and the content in animal fat is less.
Essential fatty acids are essential nutrients for human body. Insufficient absorption of essential fatty acids can cause rashes, hematuria, lactation disorders and other diseases. The essential fat needed by the fetus is supplied by the mother through the placenta, so in order to make the child grow up healthily, you should eat more vegetable oil during pregnancy.
Animal fat is an important source of fat-soluble vitamins A and D, which play a decisive role in children's vision and bone development.
Therefore, fat is an indispensable nutrient in human diet. Too little fat absorption will lead to insufficient heat intake and lack of essential fatty acids, which is harmful to embryo, infant development and maternal health, and also lead to vitamin A, D, E and K deficiency due to poor absorption of fat-soluble vitamins.
Fat mainly comes from vegetable oil and animal oil. Except rapeseed oil and tea oil, the content of essential fatty acids in vegetable oil is higher than that in animal oil. For example, sunflower oil, soybean oil, sesame oil, corn oil and peanut oil are all oils with high nutritional value, which can not only provide heat energy for pregnant women, but also meet the needs of mothers and fetuses for fatty acids.
Carbohydrate (sugar)
Carbohydrate is also the main source of human calories. According to its structure, it can be divided into monosaccharide, disaccharide and polysaccharide.
The monosaccharides in food are glucose, fructose and galactose; Disaccharides are sucrose, lactose and maltose; Polysaccharide is composed of many glucose molecules, mainly starch, and another polysaccharide is crude fiber, including cellulose, hemicellulose and pectin, which is more abundant in vegetables and fruits.
Supply of carbohydrates: For starchy foods, satiety should prevail, neither too little nor too much. According to the calculation of thermal energy, 60% of the total thermal energy is appropriate.
water
Water is the most abundant substance in the human body. This is the guarantee of normal physiological activities of human tissues, so the human body must consume a certain amount of water every day.
Water demand varies with weight, age, environment and labor intensity, and older people need more water. Pregnant women need more water than ordinary women.