trans-fatty acids (TFA)
Trans-fatty acids (TFAs) are unsaturated fatty acids in which at least one of the double bonds is trans-configured. Trans-configured means that the substituents of the double bond are on the opposite side of the double bond as compared to cis-configured.1
Occurrence in foodstuffs
Trans-fatty acids primarily occur in foodstuffs esterified with glycerol as triglyceride. In vegetable oils which undergo industrial hardening, TFAs are produced as a by-product from unwanted shifting of the cis-configuration into the trans-configuration. By contrast, native vegetable oils (oils which have not been refined or technically influenced) do not contain TFAs. In vegetable oils with high levels of polyunsaturated fatty acids, TFAs are formed by intense heating (e.g. by frying). Unlike in native vegetable oils, TFAs occur naturally in animal fats such as milk fat. They are formed in the rumen by anaerobic bacterial transformations during digestion. 1
According to current knowledge TFAs increase the LDL cholesterol level (Low Density Lipoprotein, commonly known as bad cholesterol) and lower the HDL cholesterol level (High Density Lipoprotein, commonly known as good cholesterol) in the blood and thus increase the risk of coronary heart diseases. If the consumer takes in comparatively low amounts of TFAs, these negative effects do, however, relativise again. 1-3
It is suspected that there are other links between the consumption and health effects of TFAs, for example hypertension, insulin resistance, risk of cancer and allergies, however there is no conclusive assessment by the European Food Safety Authority (EFSA) as yet.2
In January 2011 the EU Commission issued a recommendation on investigations into the levels of acrylamide in food that specifies indicative values that are comparable to the German signal values. These indicative values apply instead of the German values. So far there are no European indicative values for “lebkuchen” (German type of gingerbread), potato fritters or coffee substitute, so in these cases the German maximum levels continue to apply.
As of 15 May 2019, Annex III Part B of Regulation (EC) No. 1925/2006 stipulates that the level of trans-fatty acids other than those occurring naturally in fat of animal origin must not exceed 2 g per 100 g of fat in foodstuffs destined for the end consumer and in foodstuffs intended for distribution to retail trade.
Foodstuffs that do not comply with this regulation may only be put into circulation on the market until 1 April 2021.
There are no legal regulations stipulating how naturally occurring trans-fatty acids are to be accounted for when evaluating levels of TFAs calculated by analysis. For now, it is up to the respective experts to interpret this. Commentaries and legal practices are yet to be established in this respect.
In addition, there are other legal bases, which contain specific requirements regarding maximum levels of TFAs.
According to the specifications of the German dietary regulation (DiätV) and the new Regulation (EU) No. 2016/127, which will supersede the German dietary regulation from 22 February 2020 at the latest, the levels of TFAs in infant and follow-on formula must not exceed a maximum of 3% of the entire fat content. Further, there are special regulations for their levels in olive oil as per Regulation (EEC) No. 2568/91.
Currently there are no analytical methods which can distinguish between TFAs from natural sources and those from food processing. 2
At ifp TFAs are determined within the fatty acid spectrum by way of gas chromatography as a methyl ester in accordance with ISO 5508/5509: 1990 (GC FID). We would be happy to provide you with our diagnostic range on request.
3 Dariush Mozaffarian, Martijn B. Katan, Alberto Ascherio, Meir J. Stampfer, Walter C. Willett: Trans Fatty Acids and Cardiovascular Disease. In: Massachusetts Medical Society (ed.): New England Journal of Medicine. Vol. 354, No. 15, 2006, p. 1601–1613, doi:10.1056/NEJMra054035.