In recent years,"trans fatty acids"have become a hot topic in the media and the public."trans fatty acids have great health risks","trans fatty acids are a time bomb on the table"and other conclusions have been frequently reported,which has formed the impression of"comprehensive denial of trans fatty acids"in the public.In fact,individual media exaggerated to trans fatty acids and harm,and errors of the baked goods related raw materials,margarine,hydrogenated vegetable oil,planting the fat end,shortening,generation of direct equivalent of trans fatty acids,cocoa butter and other some cognitive one-sided,errors caused by inaccurate reports the panic,some consumers to the industry and related enterprises take their toll and economic losses.To this end,the China Food Rumor Retorting Alliance and China Baked Food Sugar Products Industry Association invited relevant experts to have an objective and fair interpretation of trans fatty acids.

　　What are trans fats,trans fatty acids?

　　Trans fatty acid(TFA)is a general term of unsaturated fatty acids with one or more non-conjugated trans double bond and all isomers on the carbon chain,which is a non-essential fatty acid for human body.We often refer to fats as triglycerides,which are formed from fatty acids and glycerol.This is true of animal oils and vegetable oils.Trans fatty acid is just one kind of fatty acid,because its chemical structure has one or more"non-conjugated trans double bond"is named,is a kind of unsaturated fatty acid.Fats that contain trans fatty acids are called trans fats.

　　Where do trans fatty acids come from?What are the health implications?

　　There are two sources of trans fatty acids in food,namely,natural sources and processed sources.Natural food is mainly the meat,fat,milk and dairy products of ruminant animals,such as cattle and sheep.Processing sources are mainly generated in the hydrogenation and refining process of vegetable oil,and a small amount of trans fatty acids will be produced in the process of food frying and frying when the oil temperature is too high and the time is too long,and trans fatty acids from processing sources are the focus of attention.

　　According to the survey,nearly half of the trans fatty acids consumed by Chinese people come from vegetable oils,with beef,mutton and dairy products also taking a large proportion.

　　It was once mistakenly believed that trans fats were deposited in the body and would not be metabolized.Studies have shown that trans fats are metabolized in the same way as regular fats,and no differences have been found in the metabolic pathways of trans fats in infants,children,adolescents and adults.Some studies have shown that trans fats interfere with the metabolism of other essential fatty acids.But the EU says it should not be affected as long as the intake of essential fatty acids is appropriate.

　　There is no definitive link between trans fatty acids and health effects such as obesity,cancer,diabetes,growth,reproductive health,Alzheimer's disease,depression,and violence.What is clear is its association with cardiovascular disease.At the same time,the academic consensus is that trans fatty acids are not essential fatty acids for human body,and have obvious potential harm to health.

　　Studies in recent decades have shown that high intake of trans fats can increase the risk of cardiovascular disease,such as lowering"good"HDL cholesterol and increasing"bad"LDL cholesterol.But there is not enough evidence to suggest that trans fats cause other harm.

　　There's nothing wrong with eating fewer trans fats,but it's almost impossible to eat none of them,because they're found in cattle,sheep and dairy products,which is why no national nutritional guidelines say"eliminate trans fats from the diet."The National Academy of Sciences recommends eating as little trans fat as possible while making sure you're getting enough nutrients.

　　The harm of trans fatty acids to health is the result of long-term accumulation.As long as you don't eat much,the risk to health is controllable.The key is to control the amount.To avoid the risks associated with excessive intake of trans fats,the World Health Organization(WHO)recommended in 2003 that the energy supply of trans fats should be less than 1%.The energy ratio of trans fats is defined as the percentage of total dietary energy intake provided by trans fats,which equates to about 2.2 grams of trans fats for an adult with a daily energy intake of 8,400 kilojoules.

　　Hydrogenated vegetable oils are not equal to trans fatty acids

　　Hydrogenation of vegetable oil has been used commercially since the 1970s,initially as a"shortening"replacement for"unhealthy"lard.Hydrogenated vegetable oils are mainly used in the baked goods and confectionery industries.They can also be used in beverages,ice cream,frying and other food industries.They are commonly found in the fillings,coatings or cakes of bread,biscuits,cakes,cocoa butter chocolate substitutes and other foods.

　　It should be noted that trans fatty acids are not produced in vegetable oils until they are fully hydrogenated.If they are completely hydrogenated,they are not trans fats but saturated fats.Therefore,hydrogenated vegetable oils cannot be equated with trans fatty acids.Of course,complete hydrogenation will make the content of saturated fat rise significantly,and should not be eaten too much.

　　The refining process of vegetable oil is mainly to remove impurities and peculiar smell and improve the sensory and technological properties of the oil.Due to the high temperature treatment procedure,a small amount of trans fatty acids are produced.The vegetable lampblack point after refining rises obviously,intuitive feeling is lampblack less.In addition,refined oils are more durable because they remove aldehydes and ketoacids.In short,the benefits of vegetable oil refining outweigh the disadvantages.

　　Why does the food industry use hydrogenated fats?

　　Initially,some processed foods because of the features you need to use animal fats as a source of fat,but then the experts found that saturated fatty acids found in animal fat cholesterol will do harm to the heart,so begin to consider substitute vegetable oil(including cholesterol),but the vegetable oil are mostly composed of unsaturated fatty acids,susceptible to oxidation,cannot be stored for a long time;Normal for liquid,not conducive to food characteristics.Therefore,the use of hydrogenation technology to make vegetable oils into solid or semi-solid,the advantages of good antioxidant stability,long storage period,can not only meet the processing needs,but also because it does not contain cholesterol,to avoid the harm to the heart.Therefore,hydrogenated fats are widely used in the food industry.

　　At present,most oil production enterprises use palm oil as the raw material of hydrogenated oil,which makes the content of trans fatty acids in hydrogenated oil very low.At the same time,the content of trans fatty acids can be reduced by enzymatic or chemical lipid exchange,product formulation adjustment,extraction technology,improved hydrogenation technology and other technologies.In recent years,many regular oil manufacturers in China have taken effective measures and improved production technology to produce vegetable oil with low trans fatty acid content or almost no trans fatty acid content.

　　The General Rules for Nutrition Labeling of National Standard for Food Safety Prepackaged Foods(GB28050-2011),which was implemented on January 1,2013,stipulated that if the food ingredients contain hydrogenated and/or partially hydrogenated fats or fats are used in the production process,the content of trans fatty acids must be marked in the nutrition information table of the food label.If the content of trans fatty acids in 100 grams or 100 milliliters is less than 0.3 grams,it can be labeled as"0."Similar statements include no trans fatty acids,no trans fatty acids,no trans fatty acids,100%trans fatty acids,0%trans fatty acids,and zero trans fatty acids,all of which meet the standard requirements.Therefore,when buying packaged food,consumers should pay more attention to the nutrition facts label if the ingredient list includes any of these ingredients.They can choose foods with no or low trans fatty acids.

　　How are trans fatty acids regulated internationally?

　　The trans-fatty acid management measures of various countries can be roughly divided into the following three methods:

　　One is through the labeling management,such as mandatory or voluntary labeling,that is,the content of trans fatty acids is marked on the food label,and the claim is required,China belongs to this category.In the United States,no more than 0.5 grams of trans fatty acids per serving can be labeled,while the European Union has adopted voluntary labeling.

　　The second is dietary recommendations,which suggest that the trans fatty acid intake of local residents should be as low as possible,or no more than a certain level,as in the Netherlands.A few countries have set content limits,such as Denmark,which stipulates that all commercially available fats and fats contain no more than 2g trans fatty acids per 100g.

　　Is the intake of trans fatty acids of Chinese residents more than that of western developed countries?

　　According to the"Dietary Intake Level and Risk Assessment of Trans Fatty Acid in Chinese Residents"released by the National Center for Food Safety Risk Assessment,the average daily intake of trans fat of Chinese people is 0.39 grams,equivalent to the energy supply ratio of 0.16%,which is significantly lower than the developed western countries and far lower than the recommended value of the World Health Organization(less than 1%).

　　In general,the overall health risk of trans fatty acids to Chinese residents is very low,but about 0.42%of urban residents,trans fat energy supply ratio has exceeded 1%.Most of these people are in school.The main reason for this is that they eat a lot of fatty foods.It's not just a trans fat problem.Too much energy and too much saturated fat should also be a concern.

　　What should consumers pay attention to when controlling trans fatty acids?

　　①Limit the amount of vegetable oil used during cooking.

　　②Pay attention to the content of trans fatty acids on the food label when buying food,and try to choose foods with no trans fatty acids or low trans fatty acids content.

　　③Don't eat large amounts of animal fats to avoid trans fats.

　　(4)avoid oil temperature is too high and repeatedly frying frying.

　　Besides trans fatty acids,what else should we be aware of?

　　Over-emphasis on trans fatty acids is also undesirable.Public attention to trans fatty acids should not be accompanied by the negative health effects of saturated fats and high energy intake.High saturated fat intake is an important reason for the increase of cholesterol,triglyceride and low-density lipoprotein in the blood,which can increase the risk of atherosclerosis,coronary heart disease and hypercholesterolemia,which has become one of the important reasons for the high incidence of chronic diseases in China.Diversified food,balanced diet and moderate exercise are the foundation of good health.For details,please refer to the Dietary Guidelines for Chinese Residents(2011)issued by the Chinese Nutrition Society.