The potential benefits of taking fish oil supplements include a lowered risk for heart attack and stroke in those with cardiovascular disease. Fish oil may also lower triglycerides and blood pressure, as well as slow plaque buildup in the arteries. You get similar benefits from consuming fatty fish such as tuna, trout, herring and salmon, so you may not need supplements if your diet is rich in fish oil sources. The primary method for extracting oil from fish is the wet pressing method, according to the Food and Agriculture Organization of the United Nations.
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Wet Pressing Method
Before oil can be extracted, the fish are heated to approximately 95 degrees Celsius to separate water and oil from protein. The liquid extraction, referred to as press liquor, contains water, oil, dissolved protein, vitamins and minerals. The oil is separated from other liquids by centrifuge, which separates matter of varying densities. The oil is stored in tanks and the concentrated leftover liquid matter gets mixed with the solid fish matter to produce fish meal.
Steaming is the primary method for heating fish for fish oil production. Although the wet pressing method yields a larger amount of fish oil, oil, water and solid material released during steaming is also strained to separate liquid from solid matter. If press liquor is stored in a tank, the sludge settles at the bottom and the oil rises to the top. This process is time-consuming, however, and yields a higher percentage of impurities in the oil. Centrifugation speeds up the process and creates a more pure fish oil product.
Fish that are smaller than 16 inches are sent directly to the steamer, while larger fish are hashed prior to processing. The cooking process takes approximately 15 to 20 minutes. When solids are separated from liquids, roughly 70 percent of the raw material is press liquor; the protein and bones account for the other 30 percent. The oil-free portion of the press liquor, including dissolved proteins and other nutrients, goes through an evaporation process before being added to other dry materials for meal production.
Certain types of fish, including king mackerel, shark and farm-raised salmon, are more likely to be contaminated with mercury or other toxins; however, fish oil supplements are generally free from these contaminants, according to MedlinePlus. While fish oil can provide health benefits, high doses of fish oil may interfere with blood clotting, impair immunity, increase low density lipoprotein cholesterol or cause an allergic reaction in people with fish or seafood allergies. While up to 3 grams is generally considered a safe dosage, work with your doctor to determine the right dosage for you based on your health needs.