"trans" unsaturated fatty acids
The name of trans fatty acid comes from its chemical structure, and its molecule contains reverse valence bond structures located on opposite sides of carbon atoms. Compared with cis fat, this reverse molecular structure is less likely to kink. The ingredients listed on general food labels, such as hydrogenated vegetable oil, partially hydrogenated vegetable oil, hydrogenated fat, refined vegetable oil, hydrogenated vegetable oil, hydrogenated palm oil, solid vegetable oil, ghee, artificial ghee, hoarfrost or shortening, all contain trans fats. The molecular formula of unsaturated fatty acids is divided into two structures because of the different orientation of hydrogen atoms: one is cis bond and the other is trans bond. Almost all natural unsaturated fatty acids are cis-linked, so most of the fats that animals can metabolize are cis-linked. Trans fatty acids are born after artificial hydrogenation, and they hardly exist in nature, so it is difficult for people to deal with such unsaturated fats. Once they enter the human body, most of them will stay in the human body, thus increasing the risk of cardiovascular disease.
Trans fatty acids-edible fats
Trans fats naturally contained in animal meat or dairy products are quite small; If fried repeatedly with natural fat, it will also produce a small amount of trans fat. Trans fats ingested by humans mainly come from partially hydrogenated vegetable oils. Hydrogenation is a food industry technology invented in the early 20th century. It was first used by the edible oil brand "Crisco" in 19 1 1 year. Partial hydrogenation will change the molecular structure of fat (make oil more resistant to high temperature, not easy to deteriorate, and increase the shelf life), but hydrogenation will also turn some fat into trans fat. This kind of fat is widely used in packaged food in the market and fried food in restaurants because it can increase the crisp taste of food and is easy to store for a long time.
Unlike other fats that can be ingested in the diet, trans fats are not beneficial to health, nor are they nutrients needed by the human body. Eating trans fats will increase the risk of coronary heart disease, because it can increase "bad" low-density lipoprotein cholesterol and decrease "good" high-density lipoprotein cholesterol. Health authorities around the world recommend that the intake of trans fats be minimized; It is generally believed that partially hydrogenated vegetable oil poses a greater risk to health than pure natural vegetable oil. In the report "Prevention and Control of Non-communicable Diseases: Implementing a Global Strategy", the World Health Organization has repeatedly reiterated the need to "gradually eliminate trans fatty acids". The United Nations Food and Agriculture Organization and the World Health Organization suggest that the diet should contain only a very small amount of trans fat, which is lower than the daily calorie intake of 1%. For an adult who consumes 2000 calories a day, this amount is equivalent to no more than 2g a day.
Trans fats are strictly controlled in a few countries, while more countries require food producers to indicate whether their products contain trans fats, and there are also many lawsuits (mainly against fast food restaurants) caused by trans fats. Many food companies have voluntarily stopped using trans fats in their products or increased their product lines without trans fats.