They have one or more double bonds in their carbon chain. If the UFA has a single double bond in the carbon chain, it is known as mono-unsaturated fatty acid (MUFA).
If there are more than one double bond, it is termed as poly-unsaturated fatty acid (PUFA).
Further, unsaturated FAs are termed omega-3, omega-6 or omega-9 depending upon the placement of double bond in the carbon chain.
Examples of mono-unsaturated fatty acidsPalmitoleic (16:1 n−7), cis-vaccenic (18:1 n−7) and oleic acids (18:1 n−9) are the examples of the most common mono-saturated FAs. MUFAs have single double bond. Decrease in the number of double bonds, increases the viscosity and melting point of FAs. MUFAs have higher viscosity and melting point than PUFAs. Dietary intake of MUFAs lead to decrease in anger and irritability and increase in HDL cholesterol. Olive oil, avocados, sunflower oil, canola oil and cashew nuts are great sources of MUFA.
Examples of poly-unsaturated fatty acidsPoly-unsaturated fatty acids include omega−3, omega−6, and omega−9 fatty acids. Alpha-linolenic (ALA, 18:3 n-3), linoleic (18:2 n-6) and oleic (18:1 n-9) acids and are examples of PUFA.
ALA (Omega-3) and LA (omega-6) are essential FAs for vital cellular functions, but cannot be produced by the body. Moreover, biochemically very important longer-chain forms like DPA, DHA and AA can be synthesized from the EFAs. The conversions are brought about by very important enzymes. In people with enzymatic deficiencies preventing satisfactory conversion of EFAs into longer-chain derivatives, the dietary intake of DPA, DHA or AA becomes essential.
Examples of cis and trans configuration of PUFAThe double bonds in the carbon chain can occur in cis or trans configuration.
Cis configurationMost of the naturally occurring PUFAs such as DPA, DHA and AA are examples of cis configuration. When the double bond has adjacent hydrogen atoms on the same side, it is cis configuration.
Trans configurationElaidic acid is an example of trans unsaturated fatty acid often found in partially hydrogenated vegetable oils. When the double bond has next two hydrogen atoms on the opposite sides, it is known as trans configuration. In nature, trans FA is found in small quantities in animal products and it is made commercially in lipid processing such as hydrogenation.
Examples of omega PUFAOmega-3
Alpha-linolenic (ALA, 18:3 n-3), eicosapentaenoic (EPA, 20:5 n-3) and docosahexaenoic (DHA, 22:6 n-3) acids are the common examples of omega-3 FAs. Common food sources include oily fish, marine algae, fish oil, algal oil, krill oil and flaxseed oil. Omega-3 PUFA supplementation have positive clinical effects in conditions like rheumatoid arthritis, ADHD, mental disorders, autism, depression, dementia and cognitive decline. Higher intake of omega-3 may protect from coronary disease.
Linoleic ( LA 18:2 n-6), gamma-linolenic (GLA, 18:3 n-6) and arachidonic (AA, 20:4 n-6) acids are examples of common omega-6 FAs. Vegetable oils of palm, soybean, rapeseed, and sunflower are the major sources of omega-6 FAs. Poultry, eggs, nuts and other vegetable oils also contain considerable quantities of omega-6. LA is an essential FA and is the precursor for the synthesis of AA, which is highly essential for brain functions. In the absence of dietary LA, AA becomes essential dietary requirement. Excess of AA can become a source of many inflammatory disorders due to its role in the production of eicosanoids.
Oleic acid (18:1 n-9) and eicosatrienoic acid (20:3 n-9) are common omega-9 unsaturated FA examples. They are not essential FAs as the human body can synthesize them. They are common components of animal lipids and vegetable oils. Olive, rapeseed and mustard seed contain omega-9.
The level of being unsaturated differs among the unsaturated fatty acids, depending upon the number of double bonds present. LA has two double bonds, ALA and GLA have three, AA has four, EPA has five and DHA has as many as six. They are usually attached to triglycerides or phospholipids. If they not attached to other molecules, they are known as 'free fatty acids'.
Related topics in nutritional deficiency diseases:
Examples of saturated fatty acids.
Definition of unsaturated fatty acids.
Deficiency of carbohydrates.
Mineral deficiency symptoms.
Vitamin deficiency diseases.
Protein deficiency diseases.
Protein energy malnutrition in children.
Diseases of nutritional deficiency.
Current topic in nutritional deficiency diseases:
Examples of unsaturated fatty acids