Fat in food breaks down into fatty acids when it enters the human body. Different fatty acids in fat will affect our health. Generally, vegetable oil mainly contains unsaturated fatty acids, which is good for preventing cardiovascular and cerebrovascular diseases; Vegetable oil also contains a certain amount of special fatty acids, which cannot be synthesized by human body and can only be obtained from food. It is called essential fatty acid in nutrition. Regarding the health standard of vegetable oil, the international mainstream trend is that the ratio of n-6 fatty acid to n-3 fatty acid in vegetable oil should be appropriate when there is enough n-3 fatty acid in the oil. If the ratio of n-6 fatty acids to n-3 fatty acids does not exceed 4: 1, it is beneficial to dilate arterial blood vessels, reduce blood viscosity and improve insulin sensitivity, thus preventing various chronic diseases. Most animal fats, such as lard, cream and whole milk, mainly contain saturated fatty acids, but few essential fatty acids. Some people call it bad fat. Eating too much of these bad fats will not only promote the accumulation of fat in the body, but also provide raw materials for the production of cholesterol in the body and stimulate the liver to synthesize more cholesterol.
Generally speaking, fat in a reasonable diet should account for 20-30% of total energy. The World Health Organization recommends that dietary fat should not provide more than 30% of the total energy. In 2002, the data of "China Residents' Nutrition and Health Survey" showed that people in China ate too much oil, and the types of oil they consumed were different, with great differences. The recommended daily intake of edible oil by the Nutrition Society of China is only 25g, that is, two tablespoons. But at present, the actual intake of urban residents has reached 4 1 g. In a big city like Beijing and Shanghai, the daily intake of edible oil is as high as 80 grams to 90 grams, which is more than three times that of usual. However, in reality, the fat energy supply of urban residents in China mostly exceeds 30%, and the fat intake in rural areas is also increasing steadily.
Nutrition experts suggest that the intake of animal fat should be reduced as much as possible on the premise of moderate fat intake. Soybean oil, peanut oil, rapeseed oil, corn oil, sesame oil, olive oil, etc. Because of the different fatty acid composition, it has different nutritional characteristics. The content of monounsaturated fatty acids in tea oil, olive oil and rapeseed oil is high. Many studies have shown that monounsaturated fatty acids can regulate blood lipids and prevent atherosclerosis, thus reducing the risk of cardiovascular diseases. Sesame oil, peanut oil, corn oil and sunflower oil are rich in linoleic acid. Soybean oil is rich in two essential fatty acids, α -linoleic acid and α -linolenic acid. These two essential fatty acids can reduce blood lipid and cholesterol and promote the growth and development of fetal brain during pregnancy.
Blending oil is a kind of oil, which is blended from several high-grade edible oils. Among them, soybean oil and rapeseed oil are the main blended oils, and a small amount of peanut oil is added to enhance the flavor. There are also blended oils based on sunflower oil and cottonseed oil. The nutritional value of blended oil varies with different raw materials, but it is rich in unsaturated fatty acids and vitamin E, with good flavor and stability, reasonable price and more suitable for daily cooking.
It should be noted that some "vegetable butter" or "vegetable butter" are products made by artificial hydrogenation of soybean oil, and their taste and cooking effect are similar to those of butter, and the proportion of fatty acids is similar to that of butter. Although they do not contain cholesterol, they all contain unhealthy "trans fatty acids". After people eat these foods, trans fatty acids are either oxidized or mixed into structural lipids. The latest research shows that eating a lot of trans fatty acids will increase the risk of coronary heart disease.
In a word, oil is the foundation of food, and a scientific understanding of it will make us enjoy life better. A "jingle" may help people grasp the health of oil use: safety and hygiene first, nutrition and health care second. Buy oil as needed and store it at low temperature in the dark. Cooking oil should be put in moderation, and the oil temperature should be controlled to prevent smoking. Good life grease help, balanced nutrition and healthier!