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talks about modern food technology and food supervision, some people often take trans fat as a typical example of “what was considered safe at the beginning but found harmful later”. However, is this really the case? Let history tell the future.

in 1902, German chemist William Norman found that liquid vegetable oil can be hydrogenated into solid with catalyst, which is the technology of hydrogenation vegetable oil. He applied for a patent and began to industrialize. A few years later, the annual output reached several thousand tons.

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, that is, he did not do “safety assessment” at all, nor did the regulatory authorities carry out “safety review” – at that time, all countries in the world had not started to regulate food. Like the new food technology in history, he thought it could be produced and started to produce it. Consumers think they can eat, so they buy it. At about that time, the United States began to import soybean as a source of protein. As a by-product of soybean processing, soybean oil is not so useful – vegetable oil in liquid state does not conform to their cooking habits. On the other hand, the United States is short of butter, and the solid oil obtained from hydrogenation of vegetable oil ushers in the spring. Cheap and easy to get has become its most attractive feature, and it is believed that vegetable oil is always healthier than real butter. No one cared whether it was safe – at that time, the FDA had not officially appeared. The FDA’s predecessor, too, did not have enough power to regulate food.

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the American people have been eating hydrogenated vegetable oil for decades, and their consumption is gradually increasing. When the FDA formulated the list of food additives, it was granted gras exemption. Gras means “generally considered safe.” ingredients on the GRAS list can be used without prior FDA approval. The GRAS qualification of hydrogenated vegetable oil is not subject to FDA safety review, but based on “long-term safe use” – for Americans, decades of use history is considered to be quite long.

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had been published until 1956. The famous medical journal Lancet published a report that hydrogenated vegetable oil can cause the increase of cholesterol in human body, and the editor’s review even pointed out that hydrogenated vegetable oil may cause coronary heart disease. However, this statement has not been supported by clear scientific data, so it has not been taken seriously. Not until the 1990s did people pay attention to the trans fat. Some of the unsaturated fats in vegetable oil will change from CIS structure to trans structure during hydrogenation. If these trans structures are not hydrogenated in the end and become saturated, they will remain as “trans fats.”. It has the same molecular composition as CIS fat, but its spatial configuration is different, so there will be different metabolic modes in human body. In 1997, the New England Journal of Medicine published the “nurse health study” conducted by Harvard Medical School and other institutions. The conclusion was that “the proportion of trans fat calories in total calories in daily diet increased by two percentage points (roughly equivalent to 4 grams), and the incidence of coronary heart disease doubled. There are many similar studies, but the harm is not so significant. For example, some studies concluded that the incidence of coronary heart disease increased by about 6.5% under the same conditions. In 2006, a paper conducted a “meta-analysis” of such studies – that is, the results of all these studies were analyzed together, and the conclusion was that “a 2% increase in the proportion of trans fat calories in total calories significantly increases the risk of coronary heart disease”, but the added value becomes 23%. As the meta-analysis covers more data, this 23% risk has gained more recognition. Later, a lot of literature also used this figure to measure the harm of trans fat. The risk of

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is increased by 23% (note that not 23% of them may get sick), and it is not small to say that they are big or small. For example, there are more than one million people dying of coronary heart disease every year in China. If the people of the whole country eat 4 grams of trans fat every day, this number will become 1.23 million. Based on this risk, the World Health Organization recommends that daily intake of trans fat contribute no more than 1% of total calories, or about 2G. They believe that this amount of trans fat, the increased risk is acceptable.

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trans fats have no nutritional value for human body, and their use in food is entirely to improve processing performance. In this context, the result of the “risk benefit” trade-off is that it should be eliminated. In particular, there have been many studies to explore other adverse health effects of trans fats. Although the scientific evidence is not sufficient, it can also be used as a reason for public decision-making in terms of harm. However, hydrogenated vegetable oils are widely used in European and American countries. Without it, a lot of processed food will be difficult to produce, and its harm is not so great. The regulatory authorities will only promote the food industry to gradually reduce its use through various laws and regulations, without any prohibition. For example, in the United States, in 1999, the content of trans fat was mandatory in the nutrition label; in 2006, it was added that the content of trans fatty acid should also be indicated in the nutrition label of traditional food and dietary supplements. However, this regulation is aimed at processed food and has no impact on the catering industry. As a result, some regions have implemented stricter regulations. For example, New York City has banned the sale of trans fat foods in the catering industry since 2008.

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in other countries have not completely banned trans fats. Generally, they are “usable, but indicate the content”, but the thresholds are different. For example, Denmark stipulates that the trans fat content in oil should not exceed 2%; China stipulates that no more than 0.3 g per 100 g of food can be marked as zero; while the United States stipulates that the content of trans fat in each food is not more than 0.5 g, it can be marked as zero. The so-called “one serving of food” in the United States is a customary concept. It is different for different foods. For example, 240 ml of milk, 3 ounces of meat and 14 g of vegetable oil are included. A person needs to eat more than two servings of food a day, so many trans fats labeled “0” may also lead to a total intake of more than 2G. This regulation of FDA has been criticized and approved

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