Deep sea fishFish is considered by many a healthy addition to your diet, but there’s a catch, the number of fish in the ocean are declining rapidly and fish can be contaminated with several toxins. Fish is an excellent source of many nutrients, but you can get these nutrients from other foods as well.

Fish are the best source of omega-3 fatty acids, particularly the ones known as EPA and DHA (fish oils). These fatty acids are believed to be good for your heart health. Eggs and chicken also contain small amount of these fatty acids and are an important source as well. Omega-3 fatty acids may be good for the heart, but so are many other nutrients like vitamins, minerals, phytonutrients and fibre. These nutrients we find in vegetables, nuts and seeds that also contain ALA omega-3 fatty acid, which your body slowly converts into the EPA and DHA fatty acids. This conversion is influenced by the amount of omega-6 fatty acids in your diet. High omega-6 fatty acid intake results in a lower conversion of ALA into EPA and DHA by up to 40%. This means that when you don’t get your fatty acids from fish because you’re vegetarian or vegan, it’s important to not eat too much omega-6 fatty acids. Processed foods and vegetable oils are the main source of these fatty acids.

CrabAll seafood is in various degrees contaminated with methyl-mercury, a toxic substance that is especially dangerous for a developing foetus during pregnancy. The biggest source of this mercury are emissions from coal burning power plants, mercury is heavy and falls down into nearby fields and waterways. Once in contact with water the mercury gets methylated which makes it toxic. The amounts of methyl-mercury in fish vary widely and it’s hard to find out the exact pollution level. Methyl-mercury sticks to the proteins in the fish and the bigger and older a fish is, the more the fish is contaminated. Especially predatory fish like shark, swordfish and Albacore tuna can contain levels that exceed levels considered safe.

It’s not so hard to avoid eating shark and swordfish if you want to avoid high methyl-mercury levels, but all fish are also contaminated with PCB’s, dioxins and similar chemicals, which are collectively called POP’s (Persistent Organic Pollutants). The source of these toxins are agricultural pesticides and industrial waste. Although some of these chemicals have been banned, they persist in the environment. These toxins get stuck in the fatty tissue of fish and the fish highest in omega-3 fatty acids are also the ones that contain the most POP’s. Most fish oil supplements are refined, otherwise they would contain even higher levels of POP’s. There is no safe level of intake established and even a low exposure level to these POP’s can lead to increased cancer risk, reproductive disorders, endocrine disruption and problems with your immune system.

Reef sharksFarmed fish raises some environmental questions and they also contain higher levels of POP’s. This is because fish farming reverses the food chain, big, contaminated fish are ground up and made into fish meal, which is used as feed for the young small fish. The use of antibiotics in fish farming and the artificial colours to give farmed salmon an attractive pink colour are other concerns related to farmed fish.

Fish are not an essential requirement for a healthy diet, but they can provide lots of good nutrients. However, fish is also contaminated with methyl-mercury and POPs, which can easily cancel out the health benefits of eating fish. To know which fish are likely to be the least contaminated you should know where your fish was caught, if it’s farmed or wild and where it is on the food chain. There are several guides available on the internet to help you choose the best fish for you.

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