The confusion about fats

It is evident that there is a lot of confusion about fats. If you keep in mind that fats are classified as saturated, monounsaturated, polyunsaturated and trans-fats, plus omega-3 and omega-6 fats, that there is also confusion about palm oil and palm kernel oil, and that cholesterol is also important, then it is no wonder that the public can't make head or tail of fats.

The subject of fats in the diet is quite complicated and it is not easy to sort out which fats we should eat and which ones we should avoid. Another question that causes a lot of problems is how much of each type of fat you should eat to stay healthy. Let's see if we can make sense of the fat confusion.

Basic principles
Basically it is 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. South Africa is a good example: rural black populations eat very little fat and heart attacks and atherosclerosis are practically unknown in this group; however, the white population of South Africa have a very high fat intake and heart disease is a major cause of death.

Our urban black population, who have increased their intake of fat, particularly animal fat, are rapidly catching up with the white population when it comes to heart disease.

Different types of fat
Not all fats are alike 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
  • Omega-6
  • 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 (e.g. colon cancer and cancer of the small intestine).

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
Not more than 25-30 g 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 - 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 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. Individuals who suffer from heart disease and have high blood fat levels should increase their intake of monounsaturated fat.

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
25-30 g per day

Diet tips to increase monounsaturated fat intake:
Switch to healthy Mediterranean Diet habits, such as:

  • 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 2 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 which state that they have a high polyunsaturated fat content on the label
  • 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:
25-30 g 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)

Next week we will have a look at some other fats that play important roles our diets, namely cholesterol, trans-fatty acids and essential fatty acids (omega-3 and omega-6).

-(Dr Ingrid van Heerden)

 Visit the Cholestrol centre

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