The American Heart Association recommends eating at least two 3.5 oz. servings of fatty fish per week to meet the recommended intake of omega-3 fatty acids. Omega-3 fatty acids are essential fatty acids that help reduce inflammation, which may in turn help decrease the risk for heart disease. The best sources of omega-3 fatty acids include salmon, mackerel, herring and tuna, but you must balance the nutritional need for omega-3 fatty acids with the risk of mercury poisoning that some fish present.
Albacore Tuna
You can find albacore tuna, scientifically known as Thunnus alalunga, in many oceans around the world. Canned tuna labeled as white tuna consists of albacore tuna. Environmental agencies and the Food and Drug Administration consider albacore tuna to be a medium risk for mercury exposure. Fishermen catch albacore tuna using a variety of methods including long-line, troll and pole-and-line. The mercury content of albacore tuna differs depending on the method of catch. Using the long-line method catches older and larger tuna which typically contain a higher level of mercury, while pole-and-line methods catch the younger and smaller fish.
Effects of Mercury
Mercury is a metallic chemical element found in the Earth's crust. Sea life transforms elemental mercury into organic mercury, also called methylmercury, that fish and shellfish can absorb. Although mercury serves no biological function in your body, you can be exposed to mercury through eating certain types of fish. Some types of fish contain more mercury than others, depending on their size, age and location in the ocean. When your blood contains levels of mercury your doctor refers to it as mercury exposure, but if you experience symptoms caused by the mercury you are said to suffer from mercury poisoning.
Risk
Many factors affect your risk of mercury poisoning including your age, the amount of mercury ingested, the duration of the exposure, the route of exposure and your overall health. Small children and pregnant women should take caution when eating fish because of their risk for developing symptoms of poisoning. The Washington State Department of Health recommends you eat only one serving of albacore tuna per week. To determine a safe serving size for you, eat 1 oz. of fish per 20 lbs. of body weight, which translates to approximately 4 oz. for an 80 lb. child.
Symptoms
Although a spill of elemental mercury can cause exposure when inhaled, consuming fish contaminated with mercury is the most common way to become exposed to mercury. Inhaling elemental mercury can cause headaches, mood swings, muscle weakness, emotional changes and tremors. Eating too much mercury contaminated fish can affect your nervous system, causing symptoms like impaired vision, tingling in the hands and feet, speech impairments, lack of coordination and muscle weakness.
References
- American Heart Association; Fish 101; January 2010
- Washington State Department of Health; Healthy Fish Guide; April 2011
- U.S. Food and Drug Administration; What You Need to Know About Mercury in Fish and Shellfish; March 2004
- United States Environmental Protection Agency; Mercury Health Effects; October 2010
- Monterrey Bay Aquarium: Tuna, Albacore
