Fat is an essential component of body cells membranes, it is also needed for metabolic substances that help regulate many body functions and also helps to carry and absorb vitamins A, D, E and K.
Most fat we need for health can be made by the body but some fats need to be provided in the diet as they body can not make them for itself, these are known as essential fats.
Fat also provides the body with energy, providing 9 calories (energy) per gram of fat, which is more than any other nutrient. If we eat more energy than we use, the body stores it as fat under our skin so it is important to watch how much energy dense fatty foods we eat or choose lower fat alternatives instead.
The Guideline Daily Amount (GDA) for total fat is 70g per day for adults
Fats can be divided into 2 categories; saturated and trans ('bad') fats and unsaturated ('good') fats.
Saturated fats are quite easy to spot as they are usually solid at room temperature.
High levels of saturated fat is found in fatty meat, cream, lard, full fat dairy products such as cheese, butter and yogurt as well as in cakes and pastries.
The guideline daily amount (GDA) for adults is 20g per day.
In the UK we are eating too much saturated fat. We should reduce the amount of saturated fat in our diet as eating too much can increase our risk of developing coronary heart disease by raising 'bad' LDL blood cholesterol in our blood. This results in the build up of fatty deposits in the arteries and increases the risk of heart attacks.
Easy ways to reduce the saturated fat in your diet include:
There are 2 types of trans fats - those that are produced naturally by ruminant animals (e.g. cows) and so found in foods such as meat and dairy products- and those which are man made through the hydrogenation process.
The hydrogenation process is used to turn liquid oils into solid fats e.g. vegetable oils into hydrogenated vegetable spreads.
Trans fats have a similar effect on blood cholesterol as saturated fats. There is some evidence to suggest that trans fats may have a worse effect on blood cholesterol than saturated fats on a weight for weight basis however trans fats make up a much smaller part of our diets.
Our intakes of trans fat in the UK are well below the recommended maximum level of 2% calories.
Unsaturated fats are the 'good' fats which can benefit our health. These fats are usually liquid at room temperature (with exception of coconut oil which is higher in saturated fats).
Unlike saturated fat which increases bad cholesterol in the blood, unsaturated fat can help to reduce the levels of bad cholesterol (LDL) and increase the levels of good cholesterol (HDL). There are two types of unsaturated fats, mono unsaturated (MUFAs) and polyunsaturated (PUFAs).
MUFAs do not raise the levels of blood cholesterol (LDL). It may also help to reduce it while raising the levels of good 'HDL' cholesterol.
Rich sources include olive oil, rapeseed oil, nuts (macadamia, hazel & brazil), avocados and olive oil margarine.
PUFAs are found in sunflower oil, corn oil, nuts and seeds and also in oily fish.
Some PUFAs are essential fats. This means our bodies are not able to make them for itself and so must be supplied from the diet. They are known as alpha linolenic acid (n-3) Omega 3 fats, and linoleic acid (n-6) Omega 6 fats.
They are needed for the structure of cell membranes- helping to keep them fluid which is essential for optimal body cell signalling.
Omega 6 is found in safflower oil, vegetable oils, sunflower oil, corn oil, soyabean oil and spreads made from these oils.
The western diet tends to be sufficient in omega 6 fats, as vegetables oils are mainly used for cooking.
Omega 3 fats are a group of polyunsaturated fats found in foods such as oily fish and some nuts and oils. In nuts and oils, they're in the form of ALA (alpha-linolenic acid) and in fish, a longer chain form, of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).
It is the longer chain omega 3 fats - EPA & DHA - that are most beneficial to our health and are the most effective form of these fats in our diet. Our bodies are able to convert ALA (from nuts and oils) into DHA & EPA, however we're not very good at it so it's important to get a direct supply of DHA & EPA from our diet
Oily fish - for example, salmon, sardines, herring, mackerel, pilchards, trout and fresh tuna - are the richest source of the important omega fats EPA & DHA. Tinned tuna does not provide a good source of these fats as they're lost in the canning process.
ALA is found in flaxseed oil, walnuts, walnut oil, rapeseed oil and soya oil.
Omega 3 fats are components of nerve cells and cellular membranes. The omega 3 fats found in fish (EPA & DHA) are essential for the development of the vision and the brain. These fats also help maintain a healthy heart and may help prevent stokes and heart disease as part of a healthy diet. They also have an anti-inflammatory role in the body.
As these fats are necessary for the development of the brain, it's important that women in the final months of pregnancy get enough; this is the time that the baby's brain and eyes are developing.
There are also a growing number of studies suggesting that these fats may have a role in improving cognition in the elderly, in childhood behavioural and learning difficulties such as dyslexia and ADHD and in depression. These findings have been based on a small number of studies and more research is needed to understand exactly how these fats are involved.
On average adults in the UK eat 1/3 of a portion of oily fish a week which means that we are not including enough of the beneficial long-chain EPA and DHA omega 3 fats in our diet. We should aim to eat 1.5g of long chain omega 3 fats which can be achieved by eating at least one portion (about 140g) of oily fish each week (but no more than 4 portions).
The Foods Standards Agency recommends that women who are pregnant or hope to have a baby one day should have a maximum of 2 portions of oily fish a week.
For more information visit
The British Nutrition Foundation
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