We need fat in our diet. It is a source of energy and is required by all the cells in our body particularly those in the brain. It helps the body absorb some of the nutrients we need. And it provides some essential fatty acids (fats) that the body can’t make itself.

However, like much in life, we need to get the balance right – and some fats are healthier than others.

The Good Fats –Monounsaturated Fats and Omega-3 fatty acids  

Monounsaturated fats and polyunsaturated fats are regarded as good fats.They are important for physical well being. We describe elsewhere on Age Watch evidence for the health benefits of olive oil (a monounsaturated fat) and oily fish (rich in polyunsaturated omega-3).

Olive oil’s health benefits are provided at low temperatures, incidentally. When cooked at high temperatures the effects can be harmful. For example heats of greater than 200-250˚F (93-121˚C) can damage the structure of the oil (the temperature of stove-top frying is 375-525˚F, or 191-274˚C).

We also need omega-6 foods (like vegetable oils). However, too much can be bad for us, especially when fried, cooked at a high temperature or used in processed foods. So we should eat at least an equivalent amount of omega-3 rich foods (like oily fish), to compensate.

Vegetable oils contain a mix of different types of fat. Olive oil has the highest proportion of monounsaturated, sunflower oil the highest polyunsaturated (omega- 6) and coconut oil the highest saturated fat.

Monounsaturated fats

Polyunsaturated fats/Omega - 6

Omega-3 fatty acids

Olives, Nuts (almonds, peanuts, hazelnuts, pecans, cashews), Avocados, Olive oil.

Soybean oil, Corn oil, Canola (Rapeseed oil), Sunflower oil, Sesame oil, Pumpkin seeds, Soymilk.

Fatty fish (like salmon, tuna, mackerel, herring, trout and sardines), flax seed, soy, and walnuts.

Bad Fats – Trans Fats

Trans fats in particular are believed to be bad for our health. The World Health Organisation (WHO) has concluded that industrially produced trans fats are associated with an increased risk of cardiovascular disease, infertility, endometriosis, gallstones, Alzheimer’s disease, diabetes and some cancers.

Trans fats are also called “Hydrogenated” fats. Hydrogenation is the chemical process that changes liquid oils into solid fats.

Trans fats are typically found in

Pastries, biscuits, doughnuts, muffins, cakes, pizza dough, packaged snack foods (crackers, microwave popcorn, crisps), fried foods (eg French fries/chips, fried chicken, chicken nuggets, breaded fish) and candy/chocolate bars. 

Body fat hardens arteries after middle age. That’s according to a recent research study at Imperial College – suggesting fat is more dangerous as we age. However, once bad fats have started to adversely affect your health it may not be possible to reverse the effects, so it is in our interests to limit intake of bad fat from an early age. And even if you’re older reducing the bad fats you consume can help stop your health deteriorating further. 

Fats in the Supermarket 

Traffic light labels on ready meals in supermarkets don’t differentiate between different types of fat but choosing green and amber will usually be safer.  

Sugar is converted into fat by your body, so ‘low fat’ foods which are rich in hidden sugar aren’t the solution. Check the sugar content in these foods first. 

Bad Fats – Saturated Fats? 

A range of respected health organisations have advised that saturated fats are bad for our health. These include the NHS in the UK, the US Food and Drug Administration and the European Food Safety Authority.  

However, recent reviews of research into saturated fats field have produced conflicting results. For example a meta analysis of 21 studies, published in 2010 concluded there is no significant evidence that dietary saturated fat is associated with an increased risk of heart or cardiovascular disease. However, several authors of this study were funded by organisations whose businesses involve the use of saturated fats. 

Conversely, another systematic reviewof research, published in 2011, recommended,’ permanent reduction of dietary saturated fat and partial replacement by unsaturates.’ 

Until we have definitive research findings it seems sensible not to overdo saturated fats. 

Saturated fats are typically found in

High-fat cuts of meat (beef, lamb and pork), Chicken with the skin, whole-fat dairy products (milk, butter and cream), cheese, ice cream, palm and coconut oil and lard.


  • Try to avoid trans fats. Check food labels for trans fats and avoid biscuits, pastries, fried food and processed snack foods.
  • Limit your intake of saturated fats like red meat and full-fat dairy foods.
  • Include foods containing omega-3 fats – especially fatty fish and walnuts.
  • Olive oil, avocados and nuts are helpful sources of monounsaturated fat. 

Published 12/02/14, Review date August 2017