Trans fatty acids are created when a liquid fat undergoes a process known as hydrogenation to become a solid fat. Since hydrogenated fats extend shelf life and enhance texture and consistency, many manufacturers incorporate them in their products.

Some foods, such meat and dairy products, naturally contain trans fats in small amounts. They are also present in vegetable oil that has been partially hydrogenated. If it is present, hydrogenated vegetable oil must be listed in the ingredients. Trans fats, like saturated fats, can raise blood cholesterol levels.

• Adults should not have more than about 5g of trans fats a day