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Fats, Oils and Lipids

Fats and oils belong to the lipid family. They have an essential part in our diet but which ones are good and which ones are bad?

What are Lipids?

At room temperature, lipids which are liquid are called oils and those which are solid are called fats. Smaller units of fats are called fatty acids.

The physiological functions of lipids include:

• formation of virtually all cell membranes
• formation of myelin sheath within the nervous system
• constitutes majority of the central nervous system spinal cord
• synthesis of steroid hormones
• assists in the regulation of enzymes
• insulation through subcutaneous (under the skin) adipose tissue
• protection of internal organs
• transportation, storage and utilisation of fat soluble vitamins A, D, E, K
• fuel source during lower intensity work loads
• storage of energy within the adipose tissue.

Types of Fats

There are many different kinds of fats and each one has a different purpose within the body:

• Saturated Fats
• Unsaturated Oils
• Trans Fats.

Saturated Fats

Saturated fatty acids are fully saturated with the fullest amount of hydrogen. Basically, the carbon atoms are all linked with a single bond to hydrogen atoms. These fats are hard at room temperature and generally come from animal products such as butter, cheese, lard and meat fat.

Saturated fatty acids are bad. They can increase your total cholesterol as well as the more harmful low-density lipoprotein (LDL) cholesterol in the blood. The Department of Health recommends that your saturated fatty acid intake should be limited to no more than 10% of your total calorie intake.

Common Sources of Saturated Fat

Animal	Non-animal
meat - beef, pork, lamb, venison	palm oil
poultry - chicken, duck	coconut oil
dairy - milk, cheese, yoghurt, cream, butter
eggs

Unsaturated Oils

There are two main categories of unsaturated fats which are:

• monounsaturated - single bend in molecule
• polyunsaturated - several bends in molecule

Monounsaturated fatty acids

Monounsaturated fatty acids contain less hydrogen as their carbon chains contain one double or unsaturated bond (hence "mono"). Oils which contain a lot of monounsaturates are mostly liquid at room temperature.

Monounsaturated fatty acids are thought to have the greatest health benefits. They can reduce your amount of total cholesterol, especially LDL cholesterol without affecting your good cholesterol (high-density lipoprotein - HDL). The Department of Health recommends a monounsaturated fatty acid intake of up to 12% of your total calorie intake.

Sources of Monounsaturated Fatty Acids

Monounstarurated Fat
olives, olive oil	rapeseed oil
lard	avocados
beef dripping	nuts
peanut oil	seeds

Polyunsaturated fatty acids

Polyunsaturated fatty acids contain the least amount of hydrogen because their carbon chains possess two or more double bonds (hence "poly"). Oils containing a lot of polyunsaturates are liquid at room and cold temperatures.

Although polyunsaturates can reduce your LDL blood cholesterol (the bad cholesterol), they can also reduce your HDL cholesterol (the good cholesterol) slightly. If you eat a lot of polyunsaturates then it may be a good idea to replace some with monounsaturates. The Department of Health recommends a maximum calorie intake of 10% of your total calorie intake.

Polyunsaturates have a sub category called essential fatty acids (essential because your body cannot produce them itself and so they must be obtained from your food). They are:

• omega-3
• omega-6

Sources of Polyunsaturated fatty acids

Omega 3 Fatty Acids	Omega 6 Fatty Acids
oily fish	sunflower seeds
flax oil	sunflower oil
walnuts	safflower oil
pastured eggs	pumpkin & sesame seeds

Note: all oils need to be cold pressed and remain unprocessed

The ideal ratio of omega-6 to omega-3 fatty acids is 2:1

Trans Fats

Trans fats are produced by a process called hydrogenation which changes liquid oils into solid or spreadable fats. During the highly pressurised heat treatment the structure of the atoms change.

Trans fatty acids are the worst types of fat because the body does not recognise their structure and so cannot use them for anything. Trans fats have adverse effects on blood lipid levels and increase the bad cholesterol (LDL) and decrease the healthier cholesterol (HDL). Trans fats also block the utilisation of essential fatty acids and increase the levels of a substance that promotes blood clot formation.

Foods to Avoid!

Common Foods Containing Trans Fats
many margarines	pies
biscuits	pastries
cakes	pre-prepared foods
crackers	many "low-fat" processed foods
take away foods

Summary

Food Recommendations

Avoid	Advise
margarines	organic butter, lard, dripping, olve oil and coconut oil
hydrogenated or partially hydrogenated fats	organic full fat dairy products
fats in cheap meats	organic quality meats
skimmed or low fat dairy products	oily fish
artificially lower fat products	organic seeds - lineseed, pumpkin
cheap plant oils, corn, sunflower, and vegetable	balance essential fatty acids 2:1 (omega-6:omega-3)

Remember that not all fat is bad. Try to keep saturated fat down and try to cut out trans fats altogether.