Questions and Answers on Trans-Fatty Acids

Changed on: 17.11.2017

What are Trans-Fatty Acids?


Trans-fatty acids are unsaturated fatty acids with a special structure created through both natural and food-technology processes. They are created naturally by microorganisms mainly found in the rumen of ruminants, where they convert fatty acids from ingested food into trans-fatty acids. One of the processes in food processing is fat hardening (hydration) to transform the texture and stability of oils into easier to process products with longer storage lives.

This makes it possible to produce more spreadable products, such as margarine, from liquid oils. Trans-fatty acids may be created as a by-product during this process. Their levels can be minimised as part of specific processes during fat hardening (choice of catalyst, optimising temperatures). Trans-fatty acids can also be created during heating or roasting in oil at very high temperatures.



Why can trans-fatty acids have an adverse effect on our health?

There is no evidence that trans-fatty acids have a positive function in the human body. Studies corroborate adverse effects on our metabolism: a high intake of trans-fatty acids does increase the risk of coronary diseases. LDL cholesterol (“bad” cholesterol) levels rise, “good” HDL cholesterol levels decrease. The possible connection between trans-fatty acids and other diseases is also the subject of animated discussions, but has not been fully proven to date. 

Which foods contain trans-fatty acids?

The main source for trans-fatty acids are foods that are produced using hydrated (hardened) fats. Baked goods, fast-food products and deep-fried foods contain high levels of trans-fatty acids, for example. However, the actual trans-fatty acid levels may vary widely in foods in the same category.

How can I tell whether a food product contains trans-fatty acids?

Food products can contain trans-fatty acids if they are made using hardened fats. Fats in packaged foods had to be labelled as “ganz gehärtet” (fully hydrogenated) or “teilweise gehärtet” (partially hydrogenated) on the ingredients list as of 13th  December 2014, in line with Regulation (EU) No 1169/2011 on the provision of food information to consumers. Particular attention should be paid to “partially hydrogenated” fats.