What is Dietary Fat?
Types of Fat
There are two main types of dietary fat - saturated and unsaturated.
Saturated fats (SAFA)
This type of fat is typically found in large amounts in foods from animals, e.g. meat, butter, cheese and cream. Many baked goods such as cakes, biscuits and pastries are also high in saturated fat. Excessive intake of saturated fat can increase blood cholesterol levels, one of the major risk factors for heart disease.
Once again, recommended fat intakes are based on energy needs and physical activity levels. Present guidelines suggest that no more than 11% of daily energy intake (EI) should come from saturated fat.
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Figures suggest that, as a nation, we may be eating too much saturated fat and need to cut down.
Unsaturated fats
There are two main types of unsaturated fats - monounsaturated and polyunsaturated. Most monounsaturated and polyunsaturated fats have good qualities, with one exception - trans-fatty acids are technically speaking a monounsaturated fat but offer no health benefits and can be potentially harmful.
Monounsaturated fats (MUFAs)
Oleic acid
Oleic acid is the main monounsaturated fat in our diets. This is sometimes called omega-9. It is found in significant amounts in most types of nuts, avocado pears, rapeseed oil and olive oil. It does not raise blood cholesterol and evidence shows that it reduces blood cholesterol levels if it replaces saturated fat in the diet.
Trans-fatty acids (TFAs)
TFAs raise LDL 'bad' cholesterol and reduce HDL 'good' cholesterol, increasing the risk of Coronary Heart Disease (CHD), so they are not good for health. There are no health benefits from eating trans-fatty acids and they can potentially be harmful to health. No more than 2% of the calories we eat each day should come from TFAs, but most people's diets are well within this limit. A relatively small proportion of people may have a very high intake of TFAs if they eat a lot of meat products, full-fat dairy products, cakes or biscuits, however. These people do need to take steps to cut their intake or their health could be damaged.
Trans fatty acids (TFAs) in our diet come mainly from two sources. One is when liquid oils are hardened by a process called partial hydrogenation; the other source of trans fatty acids is meat products and dairy foods. Many food manufacturers have re-formulated foods to remove partially hydrogenated oils and make them TFA-free. For instance, all brands of spreads on British shelves are virtually free of TFAs now and many big supermarket chains have also made moves in this direction.
| The most common dietary sources in the UK are biscuits, cakes, cheese, meat pies and pastries, so it is wise to watch your intake of these foods unless you know they contain no trans-fatty acids. |
Polyunsaturated fats
These are the essential fatty acids that cannot be made in our body, so we have to obtain them from food. Polyunsaturated fats can be divided into two main types - Omega-3 and Omega-6.
Omega-6 is mainly found in some meats, sunflower and corn oils and products made with these oils. Omega-6 helps reduce blood cholesterol levels if it replaces saturated fat in the diet hence helping improve heart health.
Omega-3 can be found in some vegetable oils such as flax and rapeseed oil. The other source of Omega-3 is fish oils, which are generally accepted as the most beneficial form. Like Omega-6, Omega-3 is shown to help keep the heart and circulation healthy.
So, broadly speaking...
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Dietary sources of 'good' fats Polyunsaturated - oil-rich fish, such as salmon, tuna, sardines and mackerel; vegetable oils, such as sunflower, safflower, corn and soya oils and spreads made from these. |