Trans fats

Trans fats (trans fatty acids) are unsaturated fatty acids with a “bent” structure – and the unhealthiest type of fat there is. They raise “bad” LDL cholesterol, lower protective “good” HDL cholesterol and have been shown to increase the risk of heart attack and stroke. The WHO recommends getting less than 1% of your daily energy from trans fats – at 2,000 kcal, that's just 2 grams.

They can form in three ways: during the industrial partial hydrogenation of vegetable oils (once typical of margarine, frying fat, puff pastry and packaged baked goods), when oil is heated very strongly or repeatedly (deep-frying, frying with smoking oil) – and, in small amounts, naturally in the fat of ruminants, meaning in milk fat and beef. These natural trans fats are considered harmless in normal amounts.

The good news: since April 2021, the EU has set a limit of 2 grams of industrial trans fat per 100 grams of fat in foods (Regulation (EU) 2019/649). Denmark introduced a similar rule back in 2003 and subsequently recorded significantly fewer heart attacks. Most margarines in Germany today are practically free of trans fats.

Even so, it's worth checking the ingredients list: “hydrogenated” or “partially hydrogenated” are warning signs. Typical remaining sources are fried food from takeaways, crisps, industrially made baked goods, croissants and puff pastry. At home, it helps not to let oil smoke, not to reuse frying fat, and to use rapeseed or olive oil for frying.

For families, this isn't a reason to panic but a question of habits: if you mostly cook for yourself and make fried food the exception, you're on the safe side.