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What is fat?
Fats and oils are officially known as lipids and they are insoluble in water. The difference between fats and oils is:
- Fats - are solid at room temperature
- Oils are liquid at room temperature
Fat is a type of nutrient also known as lipids. Lipids include the following types:
- triglycerides (fats and oils) - these come in various forms, both saturated (usually found in animal food sources) and unsaturated (usually found in plant foods) fats. The most preferable type of fat to consume is unsaturated, but small amounts of saturated fat can be tolerated without ill effect, as long as it is part of a healthy, well-balanced diet full of whole foods (wholegrains and natural, unprocessed foods)
- phospholipids - this is the double layer of fat that surrounds all cells in the body and needs to be maintained to keep cells healthy. Phospholipids are also found in various food sources, the most abundant is lecithin
- sterols - found both in plants (phytosterols) and in animal (cholesterol) foods. Sterols are necessary for producing many hormones, vitamin D and for making cholesterol (the body also makes its own cholesterol from other nutrients in the liver)
Triglycerides types of lipids which are formed from three fatty acids attached to a glycerol base.
Triglycerides can be either:
Apart from the membrane of the cells of the body, the other most common food source of phospholipids is lecithin, which is similar in form to a triglyceride, except that it has 2 fatty acids with a choline molecule, on the glycerol base.
Food sources of lecithin are:
- soy beans
- wheat germ
The liver makes enough of its own lecithin in normally health individuals, but dietary sources of lecithin are still usable.
Phospholipids are useful because they are fat soluble (from the lipid part) and also water soluble (from the phospho or phosphate part), which is a reason why the body cells are permeable to water. Because of their dual properties, phospholipids can help lipids move in and out of cells through the cell membrane.
The other type of lipids are sterols, very different to the other two types of lipids. Cholesterol is the most commonly known sterol and it can have both "good" and "bad" effects in the body, and in particular on the cardiovascular system.
Plants contain phytosterols, while animal foods contain cholesterol. Both these types of sterols have healthy effects on the body (except for"bad" (LDL) cholesterol, which needs to be avoided for good cardiovascular health).
The role of sterols are:
- Creation of bile acids - this is essential to help break down fats and absorb their nutrients effectively
- Creation of hormones - the sex hormons in both males and females are synthesised from sterols, as are the adrenal hormones (cortisol and alderosterone)
- Creation of vitamin D - sterols play an important role in manufacturing a type of vitamin D (which is actually classified as a hormone)
Essential fatty acids are those fatty acids that the body cannot manufacture on its own, so are required to be consumed on a daily basis to ensure good health.
The two essential fatty acids (EFAs) are:
- Omega-3 - is derived from linolenic acid. Omega 3 fatty acids are used to make cell walls supple and flexible and improve circulation by ensuring proper red blood cell flexibility and function. Omega-3 deficiency can cause a whole host of health problems - impaired memory, mental problems, tingling in the fingers, reduced immunity, high blood triglycerides and LDL ("bad") cholesterol levels
- Omega-6 - is derived from linoleic acid. Omega-6 fatty acids have anti-inflammatory properties and are useful for improving skin conditions (eczema), PMS, rheumatoid arthritis and diabetic neuropathy. Omega-6 deficiency is rare, because most people in the West get more than enough of this EFA in their diet
One main function of EFA are to produce prostaglandins, which regulate bodily functions such as:
- heart rate
- blood pressure
- blood clotting
- fertility and conception
- regulate inflammation
- encouraging the body to fight infection
The body requires these two essential fatty acids in a specific ratio to regulate and maintain many functions within the body. The ratio recommended is 4 (Omega 6) : 1 (Omega 3), but in the West, the ratio is more likely to be anywhere from 10:1 to 25:1, which current research shows is not healthy.
To learn more, go to the American Heart Association web site.
- McGuire M, Beerman KA, Nutritional Sciences: From Fundamentals to Food, 2007 Thomson Wadsworth USA
- Rolfes SR, Pinna K, Whitney E, Understanding Normal and Clinical Nutrition 7th Edition, 2006 Thomson Wadsworth USA