Composition of fish oil

Figure 2-6 Chromatogram of the Fatty Acid Composition of Fish Oil (Menhaden). Analysis of methyl esters on a 30-m capillary column. Source Reprinted from R.G. Ackman, Animal and Marine Lipids, in Improved and Technological Advances in Alternative Sources of Lipids, B. Kamel and Y. Kakuda, eds., p. 308, 1994, Aspen Publishers, Inc.

After considering the many analyses of fish oils available, the author concluded that there was only one basic fatty acid composition of fish oils from coldwater or from northern latitudes (27). Generally this is typified by menhaden oil, a species that feeds exclusively by filtering phytoplankton out of the ocean water in the Gulf of Mexico or in the Atlantic Ocean off the east coast of the United States or the... 

Table 1. Chemical composition of fish oil diet (FO diet) (% wet weight)...

Ackman, R.G. (1982) Fatty Acid Composition of Fish Oils, in Nutritional Evaluation of Long Chain Fatty Acids in Eish Oil (Barlow, S.M., and Stanshy, M.E. eds.) pp. 25-88, Academic Press, London. 

Because of the toxic nature of these oxidized components, the authors cautioned regular intake of encapsulated fish oils. The sale of oxidized fish oil products can be considered criminal as they pose potential health risks to the consumer. In addition to ensuring that the consumer is buying the authentic product, it must be fresh, with a clear and realistic shelf-life date indicated. The presence of vegetable oils in a fish oil is best tested for by examination of the sterol composition, as fish oils consist almost entirely of cholesterol and 24-methyl cholesterol (Paganuzzi, 1983). Analysis of the sterol fraction of the oil can often identify the oil, or at least indicate which oils might be present. 

The fatty acid composition of marine lipids varies significantly, especially when compared with vegetable oils. The fatty acid composition of blubber oil of marine mammals is generally similar to fish oils as it contains a large proportion of long-chain highly unsaturated fatty acids. However, the proportion of fatty acids in fish and marine mammals varies considerably (2). 

As of the time of writing (mid-2003), the FDA has announced that frani-acid contents of foods will soon be required on food composition labels. Fish oils, now omega-3 nutritional supplements in some foods, are essentially excluded from such considerations because they contain almost exclusively cw-ethylenic bonds. 

Table 5 shows the marketing and label strategies for some current marine omega-3 products sold in Halifax, Canada. Obviously samples No. 1 and No. 6 are natural oils. Perhaps No. 5 is simply winterized oil, a process demonstrated in Table 6 for menhaden oil, which follows from the tendency for DHA to be in the 2-position of fish oil triacylglycerols (81). EPA is reputed to be somewhat less specihc. In the absence of 20 1 and 22 1, the outer 1- and 3-positions may, in some molecules, present two saturated fatty acids from 14 0, 16 0, and 18 0 in one triacylglycerol molecule, which leads to the stearine composition of Table 6. 

Philbrick DJ, Mahadevappa VG, Ackman RG, Holub BJ. Ingestion of fish oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid affects fatty acid compositions of individual phospholipids of rat brain, sciatic nerve, and retina. J Nutr 1987 17 1663-1670. 

Stansby, M.E., Schlenk, H., and Gruger, E.H., Jr., 1990, Fatty acid composition of fish, in Fish Oils in Nutrition, Stansby, M.E., Ed., Van Nostrand Reinhold, New York, Chapter 2. 

Sorensen, N.S., Marckmann, P., Hoy, C.E., van Duyvenvo-orde, W., and Prince, H.M. (1998) Effect of Fish-Oil-Enriched Margarine on Plasma Lipids, Low-Density-Lipoprotein Particle Composition, Size, and Susceptibility to Oxidation, Am. J. Clin. Nutr. 68, 235-241. 

Hepatic Fatty Acid Composition of Ovalbumin-Sensitized Mice Fed High-Fat Diets Containing Different Levels of Fish Oil ... 

Two plant oil sources, namely olive pomace and olive pomace oil were selected by our research team because of their content in athero-protective substances (such as PAF inhibitors) and phenolic/polyphenolic molecules (Karantonis et al., 2008), null cost since they are natural wastes of olive oil production, and fatty acid profile, which makes them likely candidates to partially substitute fish oil in compounded fish feeds. The reference diet (fish oil diet) contained 100% fish oil (cod liver oil) and its chemical composition is shown in Table 1, while the two experimental diets olive pomace and olive pomace oil diet were compounded by substituting 8% of fish oil of reference diet, respectively (Nasopoulou et al., 2011). 

Mourente, G. Good, J.E. Bell, J.G. (2005) Partial substitution of fish oil with rapeseed, linseed and olive oils in diets for European sea bass Dicentrarchus labrax L.) effects on flesh fatty acid composition, plasma prostaglandins E2 and E2fl immune function and effectiveness of a fish oil finishing diet. Aquaculture Nutrition, Vol.ll, No.l, (February 2005), pp. 25-40, ISSN 1365-2095... 

Table 1. Average fatty acid composition of vegetable oils, animal fats and fish oils (% by weight)"...

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