Animals models are useful in nutrition because they allow researchers to investigate detailed molecular mechanisms surrounding the effects of particular nutrients. For example, the complex molecular pathways involved in the inflammatory process have been unravelled by the use of animal models. Inflammation is important nutritionally because the inflammatory process is regulated by the diet, and inflammation is linked to the development of a number of diseases. In particular, inflammation is linked to the metabolic syndrome, abdominal obesity and cardiovascular disease, arguably the same disease at different stages of development. In terms of nutrition, fish oils have been identified for their antiinflammatory effects, and this may explain their cardioprotective effects that have been reported in humans clinical trials. Inflammation may be involved in the development of dysfunction in the artery walls and this may be one cause of high blood pressure, increasing the risk of myocardial infarction significantly.
The antiinflammatory effects of fish oils in rodents has been extensively investigated. For example, in one study1, researchers fed mice typical western diets (pro-inflammatory diets containing processed foods) supplemented with fish oils. The mice were either normal genetically healthy mice or mice that had a genetic defect that gave them very high levels of low density lipoprotein (LDL) in their blood. After 12 weeks, those mice consuming diets that contains supplements of fish oils showed significantly lower levels of inflammation compared to mice not supplemented with fish oils. In addition, atheroscerotic lessions in the high LDL mice were significantly reduced in size, and this was accompanied by reductions in circulating endothelial adhesion molecules, known markers for the development of atherosclerosis. From this study there is therefore good evidence that fish oil may exert antiatherogenic effects through reductions in inflammation, and this may explain the cardioprotective effect of fatty fish.
Dr Robert Barrington’s Nutritional Comments: one of the main problems with the typical western diet is that it is pro-inflammatory. In part, this pro-inflammatory effects stems from the imbalance in omega-3 to omega-6 fatty acids that are stacked too far in the favour of omega-6 fatty acids and this creates an internal environment that favours inflammation. The idea ratio for omega-6 to omega-3 fatty acids is about 3 to 1, but in the typical western diet it may be as high as 20 to 1. Fish oils are beneficial because they contain omega-3 fatty acids, and this redresses the imbalance, and reduces the pro-inflammatory effect of the western diet. To further reduce inflammation the omega-6 content of the diet should also be reduced, until the ratio of omega-6 to omega-3 fatty acids is close to 3 to 1. This means consuming less vegetable oils, a rich source of omega-6 fatty acids. Fish oils can be consumed as supplements, or via the consumption of fatty fish such as salmon, trout and mackerel.
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