Eating fish may reduce the risk of heart attack, but it is important to steer clear from the type of fish that contains the most amounts of mercury, according to experts from Umeå University in Sweden.

The researchers have worked together with teams from Finland and other countries in order to assess whether the advantages of heathy fatty acids outweigh the risks of mercury proportion.

Previous research has said that individuals who consume fish have a decreased risk of heart disease, compared to those who eat none or very little. However, certain types of fish carry pollutants from the environment, which can be detrimental to the health of humans.

Methyl mercury, which can be found in many types of fish, may actually raise the risk of cardiovascular disease. Therefore, consuming fish with a lot of mercury, or with ample amounts of pollutants, can severely increase the risk of heart problems. However, if people are too health conscious of fish, they increase their risk of the disease because they are not receiving the benefits of healthy fish.

A recent study said that tuna, which has high levels of mercury, should be given to children less often.

The current research, which will be published in the October 2012 issue of American Journal of Clinical Nutrition (AJCN), was carried out with the intention of finding a middle point between not eating any fish and eating too much, or types that are unhealthy.

The authors analyzed why heart attack risk is linked to the amount of mercury and omega-3 fats in the body due to fish consumption. They did so by measuring hair and blood samples of volunteers who had been involved in other trials in eastern Finland and northern Sweden. The blood samples of the Swedes were taken from the Medical Biobank in Umeå. Researchers compared blood from the patients who had suffered a heart attack after their check-up appointments and those who remained in good health with no heart attacks.

They found that while mercury content increased the chance of heart attack, omega-3 fatty acids decreased the risk. The researchers noted that higher risk of heart attack due to mercury consumption was only prevalent when there was a large amount of pollutants found in the body. If there was a high level of omega-3 fatty acids, the risk was low.

The findings suggest that it is important and beneficial to reach an equilibrium between healthy and unhealthy content found in fish. In this particular study, the environmental pollutant used was mercury. However, in regards to organic pollutants, such as dioxin and PCD, the results are the same. The authors note, though, that there has been no trial done thus far concerning these substances.

According to the Swedish National Food Agency, 2-3 servings of fish should be consumed per week. However, Swedes tend to eat predatory fish, which have a high amount of mercury and should not be eaten on a regular basis. In addition, a study conducted by the National Food Agency revealed that 7 out of 10 people in Sweden do not eat enough fish.

A 2011 study said that people who eat fish on a regular basis have lower blood glucose concentrations, and a lower risk of cardiovascular disease and type 2 diabetes. The researchers conclude that it is safe, as well as beneficial, to eat fish, but staying away from fish with high levels of pollutants is important in avoiding health problems.

Written by Christine Kearney