Healthy fat: Workers sort salmon at Leroy Aurora'€™s plant in Skjervoy, Norway. (Courtesy of Marius Fiskum)

For the health conscious, fat is frowned upon, but there is one fat that you should never even think about cutting back on: omega-3 fatty acids.

Omega-3 fatty acids come in several forms but those called DHA and EPA found in certain fish are the types that provide the best health benefits, from lowering the risk of heart disease and preventing stroke to protecting you from dementia in old age.

There is another type called ALA, found in certain vegetable oils, walnuts and dark leafy vegetables like spinach. But this type is not as good because the body has to change a small portion of it into DHA and EPA.

Scientists say that omega-3 is useful to help avert the risk of various ailments such as heart disease, depression, arthritis and dementia and will eventually help you age well. Not only are the acids good for your health, they are also said to be good for brain development in children.

Ragnar L. Olsen, a senior seafood researcher at the Arctic University of Norway in Tromso, says the omega-3 fatty acids are produced by phytoplankton in the ocean. Fish and shellfish from the sea are the only food containing DHA and EPA.

'€œEPA and DHA are found in large amounts in fatty fish and fish oils [...] and that'€™s the main reason for the recommendation to eat seafood,'€ Olsen said in a lecture on seafood and human health for visiting Indonesian journalists in Oslo.

Some fish have higher levels of omega-3 fatty acids than others. Nutritionists'€™ top choices are trout, herring, mackerel, tuna, sardines and salmon, while shark, king mackerel, swordfish and tilefish are not recommended because they have high levels of mercury from the water and from the organisms that they consume.

Chronic exposure to mercury is known to have adverse effects on the immune system and cardiovascular function.

Farmed: Sea cages where salmon are grtown to a weight of about 5 kilograms. (JP/Pandaya)
The omega-3 fatty acids are good for your heart because they curb inflammation that causes joint pain and stiffness in people with rheumatoid arthritis, lower levels of blood fats linked to heart diseases and slow the buildup of plaque in blood vessels that triggers stroke.

'€œEating fatty fish once or lean fish twice a week is recommended for both primary and secondary prevention of coronary heart disease. A definite statement cannot be made about the dosage of EPA-DHA required for secondary prevention of the disease,'€ Olsen said.

Omega-3 in oily fish has also been traditionally touted as '€œbrain boosting'€ for children although they are cautioned against consuming types of the fish known to have high levels of mercury.

Fish consumption is also commonly linked with the slower cognitive decline that occurs with age. But Olsen said that further study was needed to determine if fat composition is the relevant dietary constituent.

However, not all types of fish and seafood are recommended for health reasons. Some experts have cautioned us about contaminated fish. The US Food and Drug Administration (FDA) has advised that young children as well as women planning on becoming pregnant or who are nursing, should avoid fish known to have high levels of mercury.

In response to warnings that farmed fish, which rely on a man-made '€œunnatural'€ diet, are '€œless healthy'€ for you than those found in the wild, Olsen said that both were equally as good when it came to omega-3 fatty acids and vitamins.

An advocate of aquaculture, Olsen says, '€œFish oil is partly replaced by plant oils in the feed of farmed fish. Does this mean that the fish becomes a plant and it'€™s not seafood anymore?'€ Quoting a study by Norwegian College of Fishery Science, he said: '€œFarmed Atlantic salmon is a good source of long chain omega-3 fatty acids.'€

Grete Lorentzen, a researcher with Nofima in Tromso, said listeria monocytogenes was bacteria found in a wide-range of ready-to-eat food products such as sushi and smoked salmon. Although it is rare and eliminated by cooking, listeria can be a serious threat to human health and Norwegian authorities conduct frequent surveillance of the bacteria in salmon. In the US, about 2,500 cases are uncovered every year.

Health activists have warned of the potential health risks associated with the unnatural diet of caged fish, which is commonly made from corn, grain, poultry and fish, while wild fish are said to be more healthy for you because they rely on natural, marine organisms like plankton to survive.

In addition to the artificial feed, caged fish may be given a concoction of vitamins and antibiotics '€” something completely unnatural '€” to speed up growth and control sea lice and other diseases.

But Jon Erik Steenslid, a senior marketing official with the Norwegian Seafood Council, said no chemicals were used in fish farms in Norway, which is campaigning to boost its salmon exports to Indonesia.

Lorentzen said synthetic substances called canthaxanthin or astaxanthin were added to feed for farmed salmon to make the salmon'€™s flesh redder and more appetizing, like that of the wild salmon.

The Norwegian Food Safety Authority (NFSA) enforces strict regulations to maintain seafood safety while the National Institute of Nutrition and Seafood Research (NIFES) conducts analyses of seafood with respect to pollutants and pathogens and provides scientific advice to government and food authorities concerning the health and safety aspects of seafood.

Fish is more than just omega-3 fatty acids and that is why scientists advise people to eat fish rather than taking omega-3 supplements. Seafood is highly recommended for other nutrients, such as protein, which are more digestible than red meat, taurine, iodine, vitamins D, B12 and A as well as minerals.

So, eat more fish. If imported fish is just too pricey, more affordable locally sourced fish like tuna is just as good, Olsen said.

And you should not let all the hype about fish and seafood dazzle you.

'€œDon'€™t be fanatic about diets,'€ Olsen said.

The writer recently visited Norway at the invitation of the Norwegian Seafood Council.