The benefits of omega-3 fatty acids are well-known to many health-conscious people. Unlike the less-effective omega-3 fatty acids found in vegetables and flax seed, the omega-3 fatty acids in fish oil — namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) — have been shown to significantly increase immune function and brain development and to help prevent cardiovascular disease and cancer. The high concentration of these acids in oily fish has caused fish oil to become more and more popular as a food supplement, and concerns over the toxicity of fish and fish products have led many people to prefer distilled fish oil over less-purified varieties. The types of distilled fish oil that are available will depend on factors such as the type of fish that is used to make the distilled fish oil — such as salmon, sardines, tuna, herring mackerel and late trout — and the levels of the various fatty acids found in the oil.
The toxins and metals that commonly build up in oily fish and are found in fish oil that has not been distilled can offset any benefits provided by the high concentrations of omega-3 fatty acids when the oil is consumed. Molecular distillation, sometimes known as short path distillation, is a process that concentrates omega-3 fatty acids, refines the oil and removes metals, polychlorinated biphenyls (PCBs) and toxins that are harmful for human consumption. Molecular distillation typically involves heating the oil in a vacuum at low temperatures, which prevents the oil from oxidizing and forming dangerous trans fats.
Molecular distillation is costly, however. Some people claim that the molecular distillation process alters the oil and reduces its health benefits. Another important factor for consumers to consider when choosing a distilled fish oil is the solvent used in the distillation process. Hexane, a less-expensive solvent, can retain harmful residue that its more expensive alternative, food grade ethanol, does not.
Other factors for consumers to consider when choosing a distilled fish oil is the type of fish and parts of the fish used to make the oil, as well as the location where the fish were caught. Cod liver oil, for example, can contain a high level of vitamin A, which can lead to adverse effects, especially in pregnant women. The highest quality fish oil should list the specific fish used to produce the oil.
Distilled fish oil ideally is made from the flesh of the fish, not the inedible parts, and the fish used should be screened for disease. Most distilled fish oil supplements can be purchased relatively inexpensively at drug and retail stores. Fish oil is a food supplement and is therefore unregulated in many countries, including the United States, the purity and concentration of the various omega-3 fatty acids in any given fish oil can very greatly. A consumer who is looking to purchase distilled fish oil should always read the labels of any fish oil supplements carefully to determine their quality and effectiveness.