Omega-9 fatty acid

For an explanation of n and numerical nomenclature (such as n−9 or 18:1), see Fatty acid#Nomenclature.

Types of fats in food
Unsaturated fat Monounsaturated fat Polyunsaturated fat Trans fat Cis fat Omega fatty acids: ω−3 ω−6 ω−9 Saturated fat Interesterified fat
See also
Fatty acid Essential fatty acid

n−9 fatty acids (popularly referred to as ω−9 fatty acids or omega-9 fatty acids) are a family of unsaturated fatty acids which have in common a final carbon–carbon double bond in the n−9 position; that is, the ninth bond from the end of the fatty acid.

Background

Some n−9s are common components of animal fat and vegetable oil. Two n−9 fatty acids important in industry are:

• Oleic acid (18:1, n−9), which is a main component of olive oil and other monounsaturated fats
• Erucic acid (22:1, n−9), which is found in rapeseed, wallflower seed, and mustard seed. Rapeseed with high erucic acid content is grown for commercial use in paintings and coatings as a drying oil. Rapeseed oil, with some of the acid removed, is commonly known as canola oil.

Unlike n−3 and n−6 fatty acids, n−9 fatty acids are not classed as essential fatty acids (EFA). This is both because they can be created by the human body from unsaturated fat, and are therefore not essential in the diet, and because the lack of an n−6 double bond keeps them from participating in the reactions that form the eicosanoids.

Under severe conditions of EFA deprivation, mammals will elongate and desaturate oleic acid to make mead acid, (20:3, n−9).^[1] This also occurs to a lesser extent in vegetarians and semi-vegetarians.^[2]

List of n−9 fatty acids

Common name	Lipid name	Chemical name
oleic acid	18:1 (n−9)	9-octadecenoic acid
Elaidic acid	18:1 (n−9)	(E)-octadec-9-enoic acid
eicosenoic acid	20:1 (n−9)	11-eicosenoic acid
mead acid	20:3 (n−9)	5,8,11-eicosatrienoic acid
erucic acid	22:1 (n−9)	13-docosenoic acid
nervonic acid	24:1 (n−9)	15-tetracosenoic acid

See also

• Polyunsaturated fatty acid, lists of fatty acids including n−3, n−6, and n−9 fatty acids
• n−3 fatty acid
• n−6 fatty acid

References

1. ^ Lipomics. "Mead acid". http://www.lipomics.com/resources/fatty_acids/20_3n9.htm. Retrieved February 14, 2006. 
2. ^ Phinney SD, Odin RS, Johnson SB, Holman RT (March 1990). "Reduced arachidonate in serum phospholipids and cholesteryl esters associated with vegetarian diets in humans". Am. J. Clin. Nutr. 51 (3): 385–92. PMID 2106775. http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=2106775. 

Additional references

• Cyberlipid Center. "Polyenoic fatty acids". http://www.cyberlipid.org/fa/acid0003.htm. Retrieved February 11, 2006.