Fish has always been the best dietary source of the animal-based omega-3 fats EPA and DHA. While your body may be able to produce some of these fats, the process is relatively inefficient, so they are considered conditionally essential.1 This means to acquire sufficient amounts for optimal health, you need to consume the omega-3 fats EPA and DHA from your food.
Unfortunately, as the levels of pollution in the oceans have increased, so have the toxins you consume. If you aren’t choosy about where your fish is harvested, the pollutants in the fish may outweigh the benefits of the healthy fats. At the same time, many fish species have been overfished and dangerously depleted. Orange roughy is one example. A slow growing, deep water fish, they don’t usually reproduce until age 20 and may live up to 149 years.2
In the 1980s the popularity of orange roughy exploded and led to driving it almost to extinction. In some areas, fishing for roughy has been restricted and scientists expect it to take many years for the population to recover, if it ever does. Farm-raised fish are also not the answer as they present problems for both the environment and the consumer.3
Raising fish in a confined area results in the same kind of waste pollution problems as land-based factory animal farms struggle with. Fish farms also reduce biodiversity, spread disease and sea lice, and contaminate water with pesticides. It is important to consider not only your health but also the impact on the environment when choosing seafood for your family.
Why Tuna Is Best Avoided
Historically, tuna has been a very popular fish, and among the most widely consumed. They are known for a distinctive flavor and versatility in the kitchen. There are at least 15 different species,4 but only five are commonly fished and eaten. Depending upon the species, the adults can weigh from 10 pounds up to 500 pounds. The largest is the Atlantic bluefin tuna that is migratory and can travel at great speeds over long distances.
Yellowfin tuna are smaller, weighing approximately 125 pounds as adults, and tend to remain in their local waters. They are carnivorous from birth, eating a number of different fish, such as mackerel, herring, hake, squid and crustaceans that feed along the ocean floor.5 Their only predator, aside from humans, are orcas and sharks, placing them near the top of the food chain and increasing the amount of toxins stored in their flesh.
Clean tuna contains a number of valuable nutrients, including selenium, iron, magnesium and potassium.6 Tuna also has high levels of vitamins B12, B6, C, zinc, niacin and riboflavin, along with omega-3 fats. Unfortunately, tuna is also among the riskiest, thanks to their often-high levels of toxins. Recent research shows that, depending on where they’re caught, some tuna can contain up to 36 times more toxic chemicals than others.7
Problems with persistent organic pollutants (POPs) occurs around the world. This short news video describes cleanup efforts the Australian government has put into place.
Toxicity Levels Vary Widely From Location to Location
Researchers from Scripps Institution of Oceanography at the University of California embarked on a one-of-a-kind study involving harvesting yellowfin tuna from around the world and analyzing the contaminant levels found in each.8 Yellowfin is the second most harvested tuna species, with more than 1.3 million tons caught every year.
Since yellowfin tend to stay in the same general region from birth to death, the researchers were able to use this fish to determine if geographic location made a difference in the accumulation of toxic chemicals in the upper levels of the ocean food chain. Yellowfin tuna are also found around the world, giving scientists a unique ability to compare toxicity levels in the same species of fish caught in different locations.
The researchers were interested in measuring levels of POPs, as these pollutants are known to be resistant to degradation and thus bioaccumulate through the food chain from the tinniest plankton to the tuna harvested for your dinner plate. They analyzed 117 fish from 12 locations around the world and found every fish caught had some level of pollutants in its body.
Fish caught close to industrialized areas, such as off the coasts of North America and Europe, had an average of 36 times more toxic chemicals than the same species caught in more remote locations. However, those were the averages. The differences between individual fish were much greater as toxic levels between the greatest and least contaminated samples varied by 180 times.
The highest contamination levels were found in tuna collected from the Northern Hemisphere, including the Gulf of Mexico. Those fish from off the coast of Asia and around the Pacific Islands were relatively clean. However, it’s important to remember that every fish was found to have toxic chemicals — which should be a highly unnatural state for an animal. Only those around Asia and the Pacific Islands were relatively clean.
Toxins found included pesticides, flame retardants and polychlorinated biphenyls (PCBs). The researchers also found 90 percent of the fish caught in the northeast Atlantic Ocean, off the coasts of Maine north to Nova Scotia, and 60 percent caught in the Gulf of Mexico, had levels of toxic chemicals that would trigger health advisories in segments of the population at greater risk, such as pregnant and nursing women.