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Monday, June 1, 2009

The Seafood Dilemma

Seafood has long been considered an essential element in healthy diets. Population studies have shown that people who eat fish regularly live longer and have lower incidences of chronic disease than those who do not. Research studies confirm the health benefits of omega-3 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) which are only found in fish and seafood. However, reports of contamination with toxic compounds and environmental damage from flawed fishing practices leave some skeptical. Can the benefits of eating fish and seafood outweigh the risks?

Health Effects

The essential omega-3 fats in fish and seafood have been found to protect against cancer and heart disease. They can reduce inflammation in the body, improve cholesterol levels, and reduce the likelihood of blood clot formation. Fish fats play important roles in the prevention of heart attack, stroke, cancer and autoimmune inflammatory conditions like rheumatoid arthritis and systemic lupus erythematosus. They may also improve chronic conditions such as insulin resistance, coronary artery disease, high blood pressure, atherosclerosis, diabetes, PMS, memory loss and depression.

DHA and EPA are essential to our diet because our bodies cannot make them. Alpha-linoleic acid (ALA) is a precursor found in flax seeds, walnuts, hemp seeds, purslane and soy. It can be converted into DHA and EPA inside the body, but the conversion process is not efficient. Some experts estimate that less than one percent of ALA is converted into these healthy omega-3 fats. Furthermore, conversion becomes less efficient as we age. This puts elderly individuals who do not eat seafood at higher risk of DHA and EPA deficiency at a time when support for neurological and cardiovascular systems is more important than ever.

Despite the numerous benefits of eating fish and seafood, health concerns exist as well. Studies have shown that some species are contaminated with mercury, lead, cadmium, polychlorinated biphenyls (PCBs), dioxins, antibiotics, insecticides and pesticides. A 2004 study published in Science compared wild salmon to farm-raised salmon from across Europe and North and South America. Researchers found that the farm-raised fish had much higher concentrations of cancer-causing contaminants, including PCBs, dioxins and insecticides dieldrin and toxaphene. Given the increased risk for cancer, many experts advise limiting consumption of farm-raised salmon to one meal per month or less. I recommend avoiding it all together.

Cancer isn’t the only risk associated with eating contaminated fish. Toxins in fish have also been associated with problems in neurological, reproductive, endocrine and immune systems. Mercury can be especially dangerous for pregnant women because it is damaging to fetuses, impairing brain and nervous system development. Problems with memory, cognitive thinking, learning, language, visual and fine motor skills have been associated with exposure to mercury in utero. Symptoms in adults include problems with peripheral vision, sensation, muscle coordination, speech and hearing.

Environmental Damage

As global demand for fish and seafood continues to grow, wild fisheries are becoming depleted and fishing practices contribute to environmental problems. Bottom trawling and dragging dredge nets damage delicate sea and ocean floors. Once compromised, it can take centuries for the coral, animals and plants to return. Also, animals like seals, sea turtles, dolphins, whales and seabirds are caught unintentionally and discarded (dead or dying). The Monterey Bay Aquarium estimates that for every pound of shrimp caught in a trawl net, between two and ten pounds of other animals are harvested unnecessarily as bycatch. Alternative fishing practices such as hook-and-line fishing, trap fishing and longlining are much less damaging to the environment and other animals.

Fish farming has helped supply the increasing demand for seafood and taken pressure off wild fisheries, but aquaculture poses problems for the environment. Like other confined animal feeding operations, fish farms generate excessive amounts of waste and animals are treated with chemical agents to increase growth and control infections. Surrounding waters become polluted with fish feces, food waste, antibiotics, insecticides and pesticides. This promotes the growth of oxygen-depleting microorganisms, upsets ecosystems and threatens wild populations.

Two exceptions exist. Bivalve farms can be used to clean costal bays and estuaries by filtering farm runoff and preventing algae overgrowth. Rainbow trout aquaculture has a low impact on the environment, and nutritionally, this fish is a very good source of omega-3 fats.

Good Choices

When chosen carefully, fish and seafood can be part of a healthy diet and a sustainable future. Two general rules apply when it comes to selecting healthy and sustainable seafood. First, find species high in DHA and EPA. These usually include oily fish that live in cold water, such as salmon, halibut, herring, sardines and anchovies. Second, eat low on the food chain. Avoid large fish that eat other fish – like tuna, swordfish, marlin and shark – because these predators accumulate higher concentrations of toxic compounds than smaller fish.

The most healthful and most sustainable fish and seafood choices currently include anchovies, wild-caught Alaskan salmon, wild-caught Pacific halibut, wild-caught Atlantic herring and sardines, wild-caught black sea bass, farm-raised rainbow trout, wild-caught pink shrimp (also known as northern shrimp), wild caught spot prawn, diver-caught sea scallops, and farm-raised or wild-caught clams such as steamers, littlenecks, longnecks and cockles.

However, good and bad choices can vary by geographical area. To search for the best choices in your region, visit the website of Monterey Bay Aquarium’s Seafood Watch program. Seafood Watch is a good resource for the most current information and advisories on toxic contaminants and environmental issues, including how fish are harvested. Visit their website to browse the seafood guides and download phone apps or printable pocket versions.

Supplementation

If good seafood is hard to find, or if certain health conditions call for more concentrated consumption, fish oil supplements offer an alternative. Because many toxic compounds are fat-soluble, the purity of fish oil is very important. Companies that produce fish oil supplements should test their products for contaminants and make this information available to consumers. Many good brands exist, but Nordic Naturals stands out because they are committed to using only sustainable sources of fish. Before you take fish oil or any other new supplement, talk to your doctor about whether it is a good choice for you, and ask about an appropriate dosage.

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