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The subject of dietary fats is quite complicated and it's not easy to sort out which fats we should eat and which ones we should avoid. Another question that causes confusion is how much of each type of fat you should eat to stay healthy.
Basic principles
Basically, it's a good idea to cut down on fat intake to prevent the so-called degenerative diseases, such as heart attacks, atherosclerosis (clogging of the arteries), obesity and certain types of cancer (breast cancer in particular).
Populations that eat large amounts of fat, especially animal fat, suffer more frequently from these degenerative diseases than populations that have a low fat intake.
Different types of fat
Not all fats are similar in composition or in the effect they have on health. Every fat is made up out of fatty acids which contain carbon, hydrogen and oxygen atoms, arranged in a specific pattern. We can classify fats as follows:
- Saturated fats
- Trans fats
- Monounsaturated fats
- Polyunsaturated fats
- Omega-3 trans fatty acids
- Omega-6 trans fatty acids
- Cholesterol
Saturated fat
Saturated fats have a chemical composition in which all the so-called double bonds are saturated with hydrogen atoms. Some of the saturated fats, which are regarded as particularly harmful, are called the trans fats. These are the fats that cause most of the fat-related problems. They raise blood fats in humans, which clog the arteries and are implicated in the development of certain cancers.
To prevent these negative effects, it’s a good idea to cut down on saturated fat intake.
The following foods are rich in saturated and trans-\ fats:
- Red meat (especially beef and mutton)
- Butter
- Full-cream milk and dairy products
- Cream
- Certain plant fats such as coconut or palm kernel oil
- Hard or brick margarine (hydrogenated fats) contains mainly saturated fat and can contain trans fats
- Pies and pastries made with lard or hydrogenated fat
Recommended intake
No more than 25-30g of saturated fat a day.
Diet tips to reduce saturated fat intake
- Eat smaller portions of red meat
- Buy meat with a lower fat content, for example chicken, lean pork, venison and ostrich
- Cut off all visible fat, including the skin, of poultry
- Use low-fat, skim or fat-free milk and dairy products such as yoghurt and cottage cheese (this will prevent calcium and vitamin B2 deficiencies)
- Eat fish at least 2 or 3 times a week
- Substitute legumes (dry, cooked beans, peas, lentils or soya) for meat
- Have at least two meat-free main meals a week
Monounsaturated fat
Monounsaturated fats have a single unsaturated double bond. Monounsaturated fatty acids are not harmful to blood fats and tend to lower raised 'bad' LDL-cholesterol levels in the blood, while increasing 'good' HDL-cholesterol levels. People with heart disease and those with high blood fat levels should increase their intake of monounsaturated fats.
The following foods are rich in monounsaturated fat:
- Plant fats, such as avocado and avocado oil
- Olives and olive oil, and soft or tub margarine made from olive oil
- Nuts
- Canola oil and soft or tub margarine made with canola oil
Recommended intake
25-30g per day
Diet tips to increase monounsaturated fat intake
Switch to healthy Mediterranean habits:
- Include plenty of carbohydrate in the form of pasta, legumes and unrefined cereals
- Eat plenty of fresh fruit and vegetables for their protective vitamins, minerals and antioxidants
- Eat very little red meat, concentrating on chicken and low-fat fish to lower your fat intake
- Eat lots of olives and olive oil, nuts and avocado
- Use garlic in cooking
- Drink moderate quantities of red wine
Polyunsaturated fat
Polyunsaturated fats contain two or more double bonds and these fats are beneficial to health and help to lower blood fat levels.
The following foods are rich in polyunsaturated fat:
- Plant oils, such as soya and sunflower oil
- Soft or tub margarines with labels indicating they have a high polyunsaturated fat content
- Foods made with the above-mentioned plant oils
- Fatty fish like tuna, sardines and salmon
- Red palm oil (not to be confused with palm kernel oil, which is high in saturated fat)
Recommended intake:
25-30g per day
Diet tips to increase monounsaturated fat intake
- Use oil instead of butter for cooking
- Make salad dressings with sunflower, olive, avocado, red palm or canola oil
- Eat fatty fish (see above)
- (Dr Ingrid van Heerden, DietDoc, updated February 2009)
