23 June 2010

Do we need fats?

The answer is yes, but we shouldn't eat too much and we should know which fats are good for us, and which fats aren't.

The answer is yes, but we shouldn't eat too much and we should know which fats are good for us, and which fats aren't.

How much fat?
Fat derived from animal products can easily push up both the total amount of fat, and the amount of saturated fat, we consume.

A great deal of research has been carried out to determine the role fat plays in a whole range of degenerative diseases, such as heart disease, cancer, obesity and diabetes.

The basic message that has emerged is that we should take care not to eat too much fat in general, and that we should cut down on the amount of saturated fat in own diets.

Most people should probably cut down their intake of fats such as margarine and salad oils to 1-2 tablespoons a day. But a small amount of fat, in the form of vegetable oils, nuts, seeds and fatty fish, should still form part of our daily eating plan.

Different types of fat
Depending on their chemical composition and the effect they have on health, fats can be divided into various categories. And no, not all fats were created equal.

Fats are divided into four main classes, namely:

  • Saturated fats
  • Monounsaturated fats,
  • Polyunsaturated fats, and
  • Essential fatty acids.


According to their effect on the body and health, some fats are worse than others. In this regard, fats can be divided into:

  • Bad fats = Saturated fats, trans fats and cholesterol, which can be found in cream, butter, lard, bacon fat, meat fat, chicken skin, commercially produced cookies, crips and pastries, and also in hard brick margarine.
  • Good fats = Mono- and polyunsaturated fats, which can be found in sunflower, safflower, canola and olive oils, soft tub margarines and nuts.
  • Essential fats = Omega-3 and omega-6 fats, which can be found in fish, omega-3 enriched eggs, flaxseed, canola and soybean oils.


"Bad fats"
Generally speaking, saturated fats and cholesterol are regarded as the "bad fats", which are linked to heart disease and cancer.

These fats are found in animal products (cream, butter, lard, bacon fat, meat fat, chicken skin), and also in plant fats that have been saturated by a process called hydrogenation, e.g. hard or brick margarines.

When plant fats are processed or exposed to very high temperatures, their chemical composition is altered and so-called 'trans-fatty acids' are formed. These trans-fatty acids have been found to be very harmful to human health and should be avoided.

Don't reheat frying oil and avoid foods that contain hard, saturated fats such as brick margarine, pies and other baked goods that don’t specify what kind of fat has been used in the recipe.

"Good fats"
Mono- and polyunsaturated fats, which are found in sunflower, safflower, canola and olive oils, soft or tub margarines and nuts, are regarded as "good fats".

The idea is to replace as much saturated fat in the diet as possible with monounsaturated and polyunsaturated fats and oils.

These fats and oils can help to reduce the risk of heart disease and cancer, but they should still not be eaten in large quantities because it's not desirable to push up the total fat content of the diet. So when you select 1-2 tablespoons of fat a day, choose margarine with a high poly- or monounsaturated fat content (read the labels), and use olive, canola or sunflower oil over salad.

Essential fatty acids
There are certain important fatty acids which we cannot manufacture in our bodies and have to obtain from our diets. These are the essential fatty acids: omega-6 and omega-3.

Because western diets contain quite a lot of omega-6, derived from the soft margarines and salad oils mentioned above, we need to concentrate on ingesting sufficient omega-3.

In addition to fatty fish (such as salmon, mackerel and tuna) and omega-3 enriched eggs, flax, canola and soybean oils are rich sources of the fatty acid. Try to use at least one teaspoon of these oils per day.

Fats and obesity
Fats and oils are highly concentrated sources of energy and each gram will provide 37kJ of energy to the diet.

In other words, one tablespoon of salad oil (which weighs 15g) will contribute 555kJ of energy to your daily intake. Anyone who is trying to lose weight, should therefore reduce their fat intake and restrict their intake of fats and oils to one tablespoon (= 3 teaspoons) of mono- or polyunsaturated margarine or oil per day. Be on the lookout for reduced-fat salad dressings. A good salad dressing contains less than 3g of fat per 100g. So, start checking those labels!

The most important thing to remember is to use very small quantities of fats and oils and to concentrate on the "good fats", and foods that contain omega-3 fatty acids.

– (Dr I.V. van Heerden, DietDoc, updated May 2008)

Any questions? Ask DietDoc


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