Essential fatty acids (simply "essential-fats") are a kind of poly-unsaturated fats vital for human body, especially for the normal growth and development in infants and young children. They are also required in adults for optimum body homeostasis (metabolism).
Dietary fats are composed primarily of fatty acids and cholesterol. Fatty acids are classified chiefly based on their chemical structure as:
Saturated fats: SFA (because they have no double bonds in their chain). Examples with high percentage of saturated fats include butter, coconut oil, palm kernel oil, lard-butter, etc.
Mono unsaturated: MUFA (with one double bond in their chain). Examples of oils with more percentage of monounsaturated fats are olive oil, mustard oil, etc.
Poly unsaturated: PUFA (have more than one double bond in their chain). Examples of oils with more percentage of poly-unsaturated fats are sunflower oil, safflower oil, etc.
Trans fats: Trans fatty acids (Trans fats) is a particular form of unsaturated fat formed because of partial hydrogenation of vegetable oils. However, once inside the human body trans-fats behave like saturated fats, and thus, increase LDL or bad cholesterol levels in the blood.
As mentioned above, essential fatty acids are a kind of poly-unsaturated fatty acid that must be present in the food we eat for normal growth and development in infants, young children and adults.
The two most important essential fatty acids are;
Linoleic acid: The principal precursor of omega-6 fatty acids that play a crucial role in pro-inflammatory reactions, such as formation thrombus (blood clots), allergic reactions.
Linolenic acid: The precursor of omega-3 fatty acid that is important for growth and development.
Although omega-6 fats are pro-inflammatory, still they are required for optimum body functions such as maintaining integrity of cell membranes, healthy skin, optimal kidney function, and to combat against bacteria and viruses. In fact, both omega-6 and omega-3 must be present in the diet for normal body homeostasis. However, the diet must contain desired omega-6 to omega-3 ratio of 5:1 to 10:1. This is because, high omega-6 and low omega-3 content as in sesame(43:0), safflower(77:0), sunflower oils (69:1) can predispose to free radical mediated cell injury, impaired immune function, reduced glucose tolerance and diabetes, increased blood clot formations resulting in coronary heart disease and stroke episodes.
Soybean oil (8:1);
olive oil (8:1), etc,.
For example, the complete fat profile of Olive oil is as here;
|Item||SFA%||MUFA%||PUFA%||ω-6 to ω-3 ratio||Remarks|
|Olive oil||14||77||8||1||8:1||Highly recommended|
Omega-3 fatty acids like a-linolenic acid, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) should be present in the diet in the range of 0.6 to 1.2 percent of total calorie intake. All the omega-3's present in the nature are essentially derived from the plant kingdom such as green algae, blue-green algae, plankton, etc. Aquatic animals like fish indeed are rich in these essential fats when they feed on algae and accumulate omega fats at great levels!
Excessive consumption of fish for omega-3 may result in accumulation of heavy metals like mercury, arsenic, cadmium, lead, etc. Indeed certain fish are unsuitable for consumption and ay be advised to avoid during pregnancy for the same reason. There exist many plant sources alternative to fish such as flax seeds, hemp, pumpkin seeds, kiwifruit, purslane, nuts like almonds, walnuts that are rich in omega-3's.
Both linoleic (omega-6) and linolenic acids (omega-3) are building blocks of brain lipids. Therefore, they are absolutely essential for normal fetal and infant brain as well as body growth, and development of visual acuity.
These fats along with other fat-soluble vitamins like vitamin-A are required by the body for maintenance of healthy skin and mucus membranes.
Fats with good omega-6 to omega-3 profile has been proved to reduce LDL or bad cholesterol and rise HDL or good-cholesterol levels; thus, helps to prevent coronary heart disease (CHD) and stroke episodes.
Omega-3 fats reduce pro-inflammatory prostaglandins and leukotrienes in the body. Their deficiency may result in co-morbid conditions like dyslexia (difficulty in reading), dysgraphia (difficulty in writing) and attention deficit-hyperactivity disease (ADHD) in children.
Vegetable oils are good sources of essential fats; however, the desired ratio of omega-6 to omega-3 that should be present in them between 5:1 and 10:1.
The foods rich in essential fats are:
<<-Read on Trans fats.
Also read...->>list of recommended fats and oils.
Further reading and References:
U.S. Department of Agriculure-Trans fats