Trans fatty acids occur naturally in some animal products such as dairy products, but are also created when hydrogen molecules are added to unsaturated oils during the process of 'hydrogenation'.
Hydrogenation causes some double bonds in fatty acid chains to take on 'trans' configurations, which result in a more solid and stable fat. Trans fats are formed when vegetable oils are partially hydrogenated.
In scientific studies, trans fats have been shown to raise blood levels of total cholesterol and LDL cholesterol (so called 'bad' cholesterol) and lower HDL ('good' cholesterol). Therefore trans fats may increase the risk of heart disease. Health experts recommend that trans fats intakes be kept as low as possible. A recent report by the UK's FSA indicated that current average intake levels are not a concern and that the focus should remain on reducing the saturated fat content of the diet.
