Fish Oil
The current interest in the use of fish and fish oils has its origin in the epidemiologic observations of the Greenland Eskimos diet. The eskimo diet consists mainly of seal meat, seal fat and seasonal fish products. A low prevalence of atherosclerosis and of age-adjusted mortality has been found in this group. The eskimo diet contained total fat and cholesterol in proportions similar to the Danish diet but the former contained a substantial amount of n-3 polyunsaturated fatty acids. There are literally dozens of omega-3 supplements available in health-food stores, pharmacies, web sites, and catalogues. Omega-3 supplements are available in a variety of concentrations and characteristics. These supplements range from the highest pharmaceutical quality formulations to products of poor quality containing oxidized fish oil and possibly other contaminants. The producers process the fish oil using various methods and ship the bulk oil to distributors, who purchase the bulk oil and encapsulate it, usually in gelatin capsules. In some cases, retailers purchase the capsules already made and put their own label on the bottles. The fatty acid content of fish oil depends upon the species, season, latitude and thus the temperature, fresh or salt water, and finally its gender. It can be noted that the female with its roe, is a much richer source of fatty acids than the male. Cold water fish are the richest sources of DHA and EPA. Some species contain more than others, and the content of an individual species varies somewhat from fish to fish. The DHA content of farmed vs. wild fish can be considerably different depending upon the feed given to commercially raised fish. The source of fish is also important. Antarctica has cleaner waters than many other regions used for fish catches. For example, anchovies from Antarctica are very small fish, high in Omega 3 fatty acid content and very low on the food chain. Consuming fish 2-3 times per week is an excellent way to increase omega-3 fatty acid content. Examples of some common types of fish are given below:
Speciesn-3 fatty acids (g/100g)
n-3 fatty acids (g/100g)Mackerel 2.5
2.5Herring 1.6
1.6Trout (lake) 1.6
1.6Trout (rainbow) 0.5
0.5Salmon 1.3
1.3Cod 0.3
0.3Fish oil supplements may not be suitable for infants and small children for at least two reasons:
1) The brain has no apparent requirement for EPA. In attempting to get DHA from fish oil, too much EPA ends up being consumed.2) EPA is known to displace arachidonic acid from cell membranes. While this may be desirable in an adult who has accumulated too much arachidonic acid over his lifetime, it is not desirable for many children. In fact, fish oil ingestion in infants has produced modest decreases in growth. Cod liver and other fish oils should be avoided as the source of omega-3 fatty acids because fish liver oil contains toxic amounts of vitamin A at higher dosages. Most fish oils come from the by-products when fish meal is processed. Therefore, the quality of fish oils is not good. Most of the fish oil has been oxidated during the processing by heat, temperature and exposure to air. Theoretically, it may become rancid. The peroxide value is usually over 5.
Fish, is a very good source of protein. We should incorporate fish into our weekly diet rather than take the fish oil.
