Fish Oil

The best sources of fish oil in the diet is from the flesh of oily fish such as mackerel, herring, tuna, kippers, herring and salmon. However you do need to look carefully at the nutritional quality of the fish that you eat. For example farmed salmon fed on grain will not have the same high level of of beneficial omega-3 fats as wild salmon. Tinned tuna will have lost much of its beneficial omega-3 fats in the cooking and canning process, and tinned tuna packed in oil often uses the wrong type of oil, such as sunflower oil, which contains a high level of omega-6 fats which compete with the beneficial omega-3 fats in the body. Tinned sardines and pilchards are as good a source as the raw fish.

The Food Standard Agency's advice is that most people should eat a minimum of two portions of fish a week, and at least one of these should be of oily fish. Unfortunately most people do not eat anything like this. Taking a fish oil supplement is a popular alternative, which many people find easier, and the dose equivalent to the minimum amount of fish to eat would be about 450mg a day of combined EPA & DHA, which would be one or two fish oil capsules a day, depending on the strength. However, the British Nutrition Foundation Task Force on Unsaturated Fatty Acids suggests eating about 8g of combined EPA & DHA a week for women and 10g per week for men, which would be the equivalent of about three fish oil capsules a day. (See the Omega-3 page for more details on EPA & DHA).

Unfortunately much of the oily fish is poluted with dioxins, PCBs and mercury, which limits the amount of oily fish that should be eaten. Dioxins and PCBs accumulate in the human body, and are only slowly removed over many years, and can cause heart disease, cancer and birth defects in babies. Because of this there are extra nutritional guidelines for eating oily fish. Girls and women who may still become pregnant should not eat more than two portions of oily fish a week; while all boys and men, and women who will not become pregnant can eat up to four portions of oily fish a week. Methylmercury is also a contaminant of oily fish which can cause nerve damage and birth defects. However is is removed from the body over a period of months, and so does not accumulate in the ame way as dioxins and PCBs. Methylmercury is found in fish at the top of the food chain, who have concentrated this from eating lots of smaller fish with lower levels of contamination. This applies to swordfish, shark or marlin, and so children under 16 years, pregnant women, or those trying to concieve should not eat these. Tuna is contaminated to a lesser extent, and this is considered safe for children, but should be limited during pregnancy. 

Fish Oil is extracted form the flesh of oily fish, and contain the beneficial Omega-3 oils in a form that allows you to take a higher dose than in oils extracted from fish livers, such as cod liver oil, which also contains vitamin A and vitamin D, which are toxic if you have too much, and this limits the amount of oil you can take.

Rheumatoid arthritis can be improved in some cases by taking fish oil supplements, which can help to ease morning stiffness, tenderness and pain.

Minor stomach effects such as burping, bloating, indigestion and a fishy aftertaste can be minimised by taking fish oil supplements after food and slowly increasing the amount you take over time.

Antioxidants are important in addition to fish oil supplements as they are needed by the body to prevent oxidation of the fish oils, because if the body does not have enough antioxidants these oils can become oxidised and rancid, and these breakdown products can cause damage to the body by free radical attack. Antioxidants are contained in fruit and vegetables, and it is important to eat plenty of these if you are using fish oil supplements. You may also wish to boost their intake by taking antioxidant supplements such as vitamin E and vitamin C.