Hydrogenated fat

What are hydrogenated fats and trans fats?

Hydrogenation is one of the processes that can be used to turn liquid oil into solid fat. The final product of this process is called hydrogenated vegetable oil, or sometimes hydrogenated fat. It's used in some biscuits, cakes, pastry, margarine and other processed foods¹.

During the process of hydrogenation, trans fats may be formed. This means that foods that contain hydrogenated vegetable oil (always declared in the ingredients list) may also contain trans fats.

The trans fats found in food containing hydrogenated vegetable oil are harmful and have no known nutritional benefits. They raise the type of cholesterol in the blood that increases the risk of coronary heart disease. Some evidence suggests that the effects of these trans fats may be worse than saturated fats.

So, as part of a healthy diet we should try to reduce the amount of foods we eat that contain hydrogenated or saturated fats and replace them with unsaturated fats. And it's also important to reduce the total amount of fat we eat.

Biscuits, cakes, pastries, meat pies, sausages, hard cheese, butter and foods containing coconut or palm oil all tend to be high in saturated fats, so try not to eat too much of these.

Foods that are rich in unsaturated fats include oily fish, avocados, nuts and sunflower, rapeseed and olive oils.

Trans fats are also naturally found at very low levels in foods such as dairy products, beef and lamb.

Why we should follow a low-fat diet?

There is substantial evidence that reducing the amount of saturated fat you eat can lower your chances of developing coronary heart disease. Because of this, we recommend a low-fat diet.

Diets that are high in fat have also been associated with obesity, which is currently reaching epidemic proportions in the UK. And people who are obese are more likely to develop conditions such as diabetes and some cancers.

Eating less fat, and especially less saturated fat, leads to lower levels of total cholesterol and LDL (low density lipoprotein) cholesterol in the blood. Levels of these cholesterols are closely related to the risk of coronary heart disease.

Many people in the UK are eating too much fat, especially saturated fat. From the age of five, total fat should provide no more than 35% of our food energy (or calories), and saturated fat should provide no more than 11% of our food energy.

On average, we are currently getting 35% of our food energy from total fat and 13% from saturated fat. So we are making progress, but many people need to make substantial changes to their diet, especially in relation to saturated fat, to meet these recommendations.

You might find this guide useful if you're checking the nutritional information on food labels:

This is a lot of fat:
20g fat or more per 100g
5g saturates or more per 100g

This is a little fat:
3g fat or less per 100g
1.5g saturates or less per 100g

If the amount is between the figures given here, this is a moderate amount of fat.