Nowadays, many people know that the intake of trans fatty acids is harmful to their health, so when buying packaged food, they should consciously check the nutrition label and see the label “0 trans fatty acid” before buying. But is “0 trans fatty acid” really safe and healthy?
First of all, let’s review some of the classification of fatty acids to see what trans fatty acids are.
The fat in food is triglycerides composed of three molecules of fatty acids and one molecule of glycerol. Fat presents different characteristics and functions due to different fatty acids. We often say “saturated fat (saturated fatty acid)”, “unsaturated fat (unsaturated fatty acid)” and “trans fat (trans fatty acid)”, which are defined according to the degree of saturation and spatial structure.
Saturated fatty acids — source: meat, egg, milk, tropical vegetable oil, which are solid at room temperature, are generally saturated fat;
Monounsaturated fatty acids – source: vegetable oil;
Polyunsaturated fatty acids – source: deep sea fish, nuts, vegetable oil;
Trans fatty acids – source: various processed foods such as desserts, cream, ice cream, coffee partner, etc.
Trans fatty acids are the products of the spatial structure changes during the hydrogenation of unsaturated fatty acids. Most of the unsaturated fatty acids are cis fatty acids in natural state, only a few are trans fatty acids. Why hydrogenation? In the 1980s, due to the concern that saturated fatty acids in animal fats will increase the risk of cardiovascular disease, vegetable oil is unstable when exposed to high temperature and cannot be stored for a long time.
Therefore, the unsaturated double bond of unsaturated fatty acid is combined with hydrogen to form saturated bond. With the increase of saturation degree, the oil changes from liquid to solid, and the food processed with trans fatty acid is used It not only improved the flavor and appearance, but also extended the shelf life. However, during the hydrogenation of vegetable oil, some unsaturated unsaturated fatty acids changed their spatial structure from cis to trans, and trans unsaturated fatty acids did not have the biological activity of essential fatty acids.
In recent years, people pay more and more attention to the harm of trans fatty acids to human body. Trans fat is the real “bad fat”, which can increase the content of low-density lipoprotein cholesterol (LDL-C), reduce the high-density lipoprotein cholesterol (HDL-C), significantly increase the risk and mortality of cardiovascular disease, and also damage the brain development of children, accelerate the brain function decline of the elderly, increase insulin resistance, and cause or aggravate diabetes.
According to the Chinese dietary nutrient reference intake, the less trans fat intake should be less than 2G per person per day, the less the better. When the content of trans fat is lower than 0.3 g / 100 g (or 100 ml), it can be labeled as “0 trans fat” or “no trans fat” in the nutrition label. In this way, even if people who like snacks eat many kinds of “zero trans fat” biscuits, cakes, chocolate pies, instant noodles and instant coffee every day, they may actually consume more than 2 grams of trans fat.
In addition, in the list of ingredients on food packaging, trans fat will also be “pseudonym” as “vegetable butter”, “margarine”, “margarine”, “partially hydrogenated vegetable oil”, “cocoa butter”, “shortening”, “vegetable fat powder” and “milk essence”. We should be vigilant and pay attention to identification.
Most foods contain more than one kind of fat. We can obtain the health benefits of various kinds of fat through food diversity every day. We need to pay attention to eating less saturated fat (saturated fat is not healthy, it will increase the cholesterol and fat content of human body, and eating too much will make us fat and harm cardiovascular health. Therefore, we should eat meat moderately, especially pay attention to animal viscera and fat) To eat unsaturated fat properly (unsaturated fatty acids have the effect of regulating blood lipids, especially polyunsaturated fatty acids, which are beneficial to the prevention of cardiovascular diseases and are also important for the development of nervous system).