Fish oil - omega 3 - mechanism of action

The action of fish oil omega 3 fatty acids is may be the following:
- modulation of pro-inflammatory and prothrombotic eicosanoid (prostaglandin, thromboxane and leukotriene) production
- reduction in interleukin-1 and other cytokines.

The effects of omega 3 fatty acids are thought to be due to the partial replacement of arachidonic acid with EPA in cell membrane lipids. This leads to increased production of PG3 series prostaglandins, thromboxane A3 and series 5 leukotrienes at the expense of PG2 series
prostaglandins, thromboxane A2 and series 4 leukotrienes . Thromboxane A3 (produced from EPA) is less effective at stimulating platelet aggregation than thromboxane A2 (produced from
arachidonic acid). Prostaglandins of the PG3 series have less potent inflammatory effects than prostaglandins of the PG2 series. In addition, DHA inhibits the formation of the more inflammatory prostaglandins of the PG2 series, while EPA acts as a substrate for the synthesis of the less inflammatory prostaglandins of the PG3 series. Series 5 leukotrienes (produced by EPA) have weaker inflammatory effects than series 4 leukotrienes (produced by arachidonic acid).

Effects of fish oil Omega 3 fatty acids

Fish oil omega 3 fatty acids have a lot of benefits, they have several effects on the human body. The fish oil omega 3 benefits are the following:

- Fish oil omega 3 fatty acids has effect on alteration of lipoprotein metabolism. Fish oils reduce both fasting and post-prandial plasma triacylglycerols and VLDL cholesterol. With moderate intakes of fish oils, both HDL and LDL cholesterol tend to increase. High intakes reduce HDL cholesterol and may increase LDL in some patients. A meta-analysis of published human trials (that each provided 7 g daily of fish oils for at least 2 weeks) showed that serum cholesterol is unaffected by long-chain n-3 fatty acid consumption. However, triacylglycerols fell by 25–30%, LDL increased by 5–10% and HDL fell by 1–3%.
- Further fish oil omega 3 benefits are the prevention of thrombosis. Thrombosis is a major complication of coronary atherosclerosis, which can lead to myocardial infarction. The n-3 fatty acids have anti-thrombotic actions through inhibiting the synthesis of thromboxane A2 from arachidonic acids in platelets. Thromboxane A2 causes platelet aggregation and vasoconstriction and as a result fish oil increases bleeding time and reduces the ‘stickiness’ of the platelets. Fish oil also enhances the production of prostacyclin, which leads to vasodilatation and less ‘sticky’ platelets. These effects help to reduce the risk of thrombosis.
- The next benefits of fish oil omega 3 are inhibition of atherosclerosis. Fish oils reduce the plasma concentrations of several atherogenic lipoproteins (see above), but other mechanisms may be important. Thus, these effects may be associated with reduced synthesis of cytokines and interleukin 1α and through stimulation of the endothelial production of nitric oxide.
- Omega 3 fish oils can reduction in heart rate. A meta-analysis of 30 RCTs found that fish oil decreased heart rate by 1.6 beats per minute compared with placebo. In trials where initial heart beat was high and/or the study period was long, reduction in heart rate averaged 2.5 beats per minute. Heart rate reduction did not significantly vary with dosage of fish oil.
- Inhibition of inflammation. Diets rich in omega-3 fatty acids appear to reduce the inflammatory response.
- Inhibition of the immune response. Immune reactivity is generally reduced by omega-3
fatty acids.
- Fish oil omega 3 fatty acids have influence on arrhythmias. Fish oil may reduce the incidence of lethal myocardial infarction and sudden death. This may be due to the prevention of fatal cardiac arrhythmias. Evidence from some studies indicates an anti-arrhythmic action of fish oil, while evidence from other studies does not. In patients undergoing coronary artery bypass surgery (CABG), omega-3 fatty acids (2 g daily) substantially reduced the incidence of post-operative atrial fibrillation. In a further study in patients with a recent episode of sustained ventricular arrhythmia and an implantable cardioverter defibrillator (ICD), fish oil did not reduce the risk of ventricular tachycardia and ventricular fibrillation and there was evidence of a pro-arrhythmic effect in some patients.

Fish oil omega 3 - EPA and DHA - how much do I need

The two main fish oil Omega 3 fatty acids, the EPA and DHA in small amounts can be synthesised in the body from alpha-linolenic acid (contained in vegetable oils, e.g. soya bean, linseed and rapeseed oils). However, this conversion
may be inefficient in some individuals so other sources would be necessary.
The recommended daily DHA/EPA intake in different coutries are different. The recommended very-long-chain n-3 (omega 3) fatty acids (EPA/DHA):

- UK Department of Heath: 1 200 mg daily
- British Nutrition Foundation: 2 1250 mg daily
- International Society for the Study of Fatty Acids and Lipids: 650 mg daily
- The Danish Ministry of Health: 300 mg daily
- Deutsche Gesellschaft fur Ernahrung (DGE): 1500 mg daily



Fish oil in Wikipedia
Some information about fish oil in Wikipedia
http://en.wikipedia.org/wiki/Fish_oil

Fish oil omega 3 content - the sources and ingredients

The fish oil omega 3 content is realized to be very important recenty. Generealy there are two types of fish oil supplements:
- The first is : fish liver oil - this is generally obtained from the liver of the cod, halibut or shark.
- The second is fish body oil - this is normally derived from the flesh of the herring, sardine or anchovy.

Let's see the fish liver oil. Fish liver oil is rich in vitamins A and D. Concentrations in cod liver oil liquids normally range between 750 and 1200 μg (2500–4000 units) vitamin A per 10 ml and 2.5–10 μg(100–400 units) vitamin D per 10 ml. Halibut and shark liver oils are more concentrated sources of these vitamins.
And the fish body oil. Fish body oil is low in vitamins A and D. Vitamin E is also present in both types of fish oil and extra vitamin E is normally added to supplements.
Both fish liver oil and fish body oil are sources of polyunsaturated fatty acids (PUFAs) of the omega-3 series [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)]. These fish oil omega 3 fatty acids are may the most important parts of the oil, the fish oil benefits are connected to them.
EPA and DPA are 20- and 22-carbon molecules, respectively, with five double bonds D5,8,11,14,17, while DHA is a 22- carbon and six double-bond molecule D5,8,11,14,17,20.
All fatty acids (FA) in the fish oil omega 3 family are characterized by having their first double bond at the 3rd position counting from the terminal (o or nth) methyl group in the molecule. As with the omega 6 family, omega 3 fatty acid cannot be synthesized de novo by mammals and must be obtained from the diet.
The structure of the first fish oil omega 3: DHA



The structure of the second fish oil omega 3: EPA






Omega3 and fish oil in BBC
In BBC a short summary about fish oils and omega3 and their effect on brainpower
http://www.bbc.co.uk/science/humanbody/mind/articles/intelligenceandmemory/omega_three.shtml