Types of fats

Fat is made up of building blocks called fatty acids.

Fatty acids can differ in

  • structure
  • chain length
  • saturation (whether they are saturated, monounsaturated or polyunsaturated).

These differences affect whether they are solid or liquid. Importantly, the differences in chemical structures also can make a difference to their health effects

Fats found in foods are typically saturated or unsaturated fats. Most foods usually contain a mixture of both types. We would normally describe a food as being high in saturated or unsaturated depending on which they are a rich source of.

 

Saturated fats

What foods are high in saturated fats?

If chosen, foods high in saturated fats should only be eaten in small amounts. Examples of these foods include:

  • Fatty cuts of meat and processed meat products like bacon, sausages and salami
  • Cheese
  • Cream, crème fraiche and soured cream
  • Butter, ghee, suet, lard, coconut oil and palm oil
  • Coconut milk and cream
  • Cakes, biscuits and pastries, like pies, sausage rolls and croissants
  • Chocolate and chocolate spreads

Saturated fats and health

Saturated fat can increase the amount of a type of cholesterol called LDL-cholesterol in our blood. LDL-cholesterol is often called ‘bad’ cholesterol.

Why is high cholesterol harmful?

Too much LDL-cholesterol in our blood can cause fatty material to build up in the walls of our blood vessels and cause them to narrow. This increases the risk of blood clots, which can lead to a heart attack or stroke. ‘Good’ cholesterol (HDL-cholesterol) carries the LDL-cholesterol from the body and to the liver to be broken down, so that too much doesn't build up in our blood. 

 

Unsaturated fats

Unsaturated fats help to maintain healthy cholesterol levels. As part of a healthy, balanced diet, it is best to choose foods that contain higher amounts of unsaturated fat and less saturated fat.

There are two types of unsaturated fats: monounsaturated and polyunsaturated fats.

Monounsaturated fats are found in:

  • Some vegetable oils and spreads made from them (e.g. olive and rapeseed)
  • Olives
  • Avocados
  • Nuts

These foods are typical of the Mediterranean diet, which is associated with good heart health and a lower risk of heart disease.

Monounsaturated fats help maintain levels of good HDL cholesterol and decrease levels of harmful LDL-cholesterol.

Polyunsaturated fats are found in:

  • Some vegetable oils and spreads made from them (e.g. corn and sesame)
  • Flaxseed, sesame seeds and sunflower seeds
  • Walnuts, pine nuts
  • Oily fish (e.g. mackerel, trout and sardines).

Polyunsaturated fats help to lower LDL-cholesterol, and provide us with essential fatty acids (which the body cannot make), such as omega-3 and omega-6. Omega-3 fats are also important during pregnancy and breastfeeding to support child development.

Omega-3 fatty acids are mainly found in:

  • Oily fish (e.g. mackerel, salmon, sardines, trout, herring)

We can also get omega-3 from vegetable sources but these aren’t thought to have the same benefits for heart health as the longer chain omega-3 found in oil-rich fish. If you don’t eat fish, vegetarian sources of omega-3 include:

  • Some vegetable oils and spreads made from them (e.g. rapeseed, flax, linseed, soya)
  • Soya-based foods g. tofu
  • Walnuts

Foods are also sometimes fortified with omega-3, for example omega-3 fortified eggs. Read on to find out how to choose the right fats in your diet.