Fat is an important part of any balanced diet, but the type of fat you eat matters – particularly when it comes to cholesterol. There are ‘good’ fats and ‘bad’ fats, and, along with saturated fats, trans fats fall into the latter category. So what is trans fat, where is it found, and why is it considered bad for you? Let’s take a look.
What are trans fats?
Trans fats, also known as trans fatty acids or TFA, are a type of fat found in small amounts in a wide variety of foods. They are considered a ‘bad’ fat because, like saturated fats, they can increase levels of LDL-cholesterol in the blood. Trans fats can also decrease the level of ‘good’ HDL cholesterol, and may increase the level of triglycerides, another type of fat in the blood.
So why don’t we hear more about trans fats and cholesterol?
One possible reason for this is that on average, our intake of trans fats in the UK is well within the recommended limits. The UK Scientific Advisory Committee on Nutrition advises that trans fats make up less than 2% of our total daily energy intake; meanwhile, the 2014 National Diet and Nutrition Survey review by Public Health showed that, on average, trans fats account for 0.6-0.7% of food energy for all ages and genders.
By comparison, we are on average eating too much saturated fat: it accounts for 12.6% of our average daily energy intake, despite the recommended limit stopping at 11% maximum.
What foods contain trans fats?
Even if the average intake of trans fats is pretty low, it’s natural to be interested in knowing about trans fat and foods that contain them:
Trans fats occur naturally in small amounts in dairy and meat products, such as cheese, milk, cream, lamb, pork and beef.
There are also industrial trans fats, which can be produced through a process called ‘partial hydrogenation’. Partial hydrogenation solidifies and partially hardens vegetable oil, a process that food manufacturers find useful in the production of fried foods as well as baked foods, like biscuits, pies, and cakes. Heating vegetable oils to a very high temperature (such as in a deep fat fryer) can also produce trans fats, which is why takeaway foods, doughnuts, and a number of fried sweet foods are occasionally culprits as well.
The majority of food manufacturers for vegetable oil based soft spreads and margarines have low amounts of trans fats, which helps those of us who eat them stay well within the dietary guidelines.
How can I check whether I’m eating trans fat foods?
Unfortunately, the way food packaging is regulated means that you generally won’t see ‘trans fats’ included in the nutritional information, making a trans fat foods list complicated to produce. What you can do is look for partially hydrogenated vegetable oils or fats in the ingredients list – full hydrogenation does not result in trans fat. The higher up partially hydrogenated fat or oil appears in the ingredients list on the packet, the more trans fat it is likely to contain.
More on fats
Fats are an important part of a balanced diet, so why not learn more about them? Find guides to good and bad fats in our dedicated section here. You can also sign up to our monthly newsletter here to get regular articles and advice on having a heart-healthy diet and lifestyle.