Fish Oil and Omega-3 Fatty Acids
There is lot of buzz and some hype too around fish oil, primarily due to the presence of omega-3 fatty acids in it. There is also great deal of confusion about the necessity of fish oil in our diet and whether we should consume fish oil supplements or simply eat fish. Let us get into some details to know what fish oil, omega-3 fatty acids, EPA, DHA are and how we should consume them.
Fish oil is extracted from tissues of fatty fish, especially the livers. It is rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are long-chain poly unsaturated fatty acids (LC-PUFAs). Both, EPA and DHA are converted in the human body from dietary alpha linolenic acid (ALA), a short chain poly unsaturated fatty acid (SC-PUFA). Due to their structure, all these are a type of Omega-3 fatty acids (Omega-3s).
Role of omega-3s (EPA and DHA) and omega-6 fatty acids
While ALA is an essential fatty acid (EFA) that cannot be formed in the human body and needs to be ingested, EPA and DHA are 'conditionally essential' owing to their inefficient conversion from ALA in the human body. Seed oils of rapeseed, canola, flaxseed, soybeans, chia are abundant in ALA, whereas fish oil is considered a rich source of EPA and DHA.
In human body, Omega-3s such as EPA and DHA compete with Omega-6 fatty acids (Omega-6s), another class of LC-PUFAs, as precursors to signaling molecules such as ecosanoids. The amount and ratio of Omega-3s and Omega-6s influences ecosanoid-controlled functions such as inflammation and other health conditions. A ratio of 1:1 is considered ideal for maintaining balance in these functions.
Fish oil due to its EPA and DHA, is commonly used for diseases of heart and blood system. Other disease conditions for which it is used are those of brain, eyes, bones, joints and muscles, lungs, immune system, and kidneys.
EPA and DHA from fish
Do we get EPA and DHA when we eat fish. The answer is yes, EPA and DHA present in fish oil can be sufficiently sourced from eating fish. Fatty fish such as salmon, mackerel, herring, lake trout, sardines and albacore tuna are high in these Omega-3s. In wild fish, Omega-3s are higher in summer, while in farm fish these levels are diet dependent. Broiled or baked and non-fried fish provide them in maximum.
Fish accumulate EPA and DHA directly or indirectly through smaller prey fish, which eat microalgae and other microscopic plant like organisms, which originally synthesize EPA and DHA in their body.
There is a growing concern of contaminants such as mercury, dioxin, and polychlorinated biphenyls (PCBs) in consuming big fatty fishes such as swordfish, tilefish, albacore tuna, and king mackerel. This risk is more for children, pregnant, and nursing women.
EPA and DHA from fish oil supplements
Fish oil supplements are capsules containing fish oil. Different types of supplements have EPA and DHA in varying combinations. These supplements are usually made from oil obtained from mackerel, herring, tuna, halibut, salmon, cod liver, whale blubber, or seal blubber. The supplements are usually added with Vitamin E for preservation and may also contain calcium, iron, or vitamins A, B1, B2, B3, C, or D. Several over-the-counter fish oil supplements are available in the US and their number could be about 100. They contain oil from different fish as well as different vitamin and mineral additives and are prepared using different processes.
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