Trans fat ban: how to tell if food contains trans fats

A type of fat found in many foods, from cake frosting to popcorn, has been linked to memory loss in working-age men, new research has found.

The University of California San Diego study, published in journal Plos One, shows that men under the age of 45 who consume higher levels of trans fatty acids performed poorly on memory tests when compared to those who consumed less of the same fats.

Researchers collected data from a word-recall memory test, involving more than 1,000 people. They were shown 104 cards bearing different words and asked if they were seeing them for the first time. The average recall for men aged 45 and younger was 86 words. For each additional gram of trans fats consumed per day, an average of 0.76 fewer words were recalled. At the highest consumption level of 15.7 grams per day, men recalled 12 fewer words than those who consumed no trans fats.

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The study comes after the US Food and Drug Administration gave food companies three years to phase out partially hydrogenated oils, the main source of trans fats, from their products.

The oils, which are solid at room temperature, are often added to food to alter texture and enhance shelf life, and are made by adding hydrogen molecules to vegetable oil to make it thicker in a process called "hardening". According to the NHS, consuming trans fats can lead to high cholesterol levels, resulting in a heart attack or stroke.

The UK has been pushing for a blanket ban on trans fats for several years, according to the BBC. Campaigners in Scotland tried and failed to persuade the Scottish parliament to back a trans fats ban five years ago, The Guardian reported.

Denmark became the first country to ban trans fats in 2003. The country has seen a 70 per cent drop in coronary disease since 1980, and Scientific American speculates that the trans fat ban could have contributed to the decline. Switzerland, Sweden, Austria and Iceland have also passed similar bans.

Dr Beatrice Golomb, head researcher for the memory study, says: "As I tell patients, while trans fats increase the shelf life of foods, they reduce the shelf life of people."

How do I know if my food contains trans fats?

In the US, food manufacturers are obliged to mention fat content on the labels of any product containing more than 0.5 grams of trans fats per serving, but according to the British Dietetic Association (BDA), there are currently no legal requirements for food manufacturers in the UK to do the same.

The BDA notes that foods produced using hardened vegetable oils typically contain some trans fats. These include many fried foods, biscuits, pies and cakes. "Fat spreads and margarines that have hydrogenated vegetable oil as an ingredient will usually contain some trans fats, although reformulation has led to significant reductions in recent years," says the BDA. The association advises that people check ingredients lists for "hydrogenated fats" or "hydrogenated vegetable oils".

However, it notes that only partially hydrogenated fats, as opposed to fully hydrogenated fat, contain trans fats. The higher up the list of ingredients the partially hydrogenated fat or oil appears, the more trans fats the product is likely to contain. It adds that "many manufacturers now avoid using hydrogenated fats or have reduced the amount of trans fats in their products to very low levels".