Fish and seafood are high in Omega-3 Fatty Acids - often referred to as the “good” fats. The human body cannot make significant quantities of Omega-3 Fatty Acids on its own - highlighting the importance of getting sufficient amounts through food. While there are 6 types of Omega-3 Fatty Acids - the two main types found in seafood are eicosapentaenoic acids (EPAs) and docosahexaenoic acids (DHAs).

Typically, fish with a higher oil content are higher in EPAs and DHAs. Health benefits associated with Omega-3 Fatty Acids include:
Lowered incidence of coronary heart disease
Regulate blood clotting and vessel constriction
Help manage diabetes
Help manage skin disorders
Reduced cholesterol levels
Lowered blood pressure
Reduced lupus symptoms
Reduced arthritis symptoms
Prevent and control colitis
Reduced asthma symptoms
Increase cognitive ability (memory & focus)
Halt mental decline in older adults
Reduced depression severity
Help manage attention deficit disorder, bipolar and schizophrenia
Cancer prevention
Improved immune function
Important for pre and postnatal neurological development

Other sources of Omega-3 Fatty Acids include: flaxseed - walnuts - soybeans and tofu. However, plant sources of Omega-3 Fatty Acids are not absorbed as readily by the body and therefore may not result in the same health benefits. The majority of fish oil supplements are now made from purified fish oil. Purified fish oils are free of all contaminants present in fish making them a safe alternative - but it is recommended to not consume more than 3 grams per day - unless under physician care.

Mercury is a naturally occurring metal found in soil, rocks and water. In addition, Mercury is released into the atmosphere as a result of human activities such as, coal-fired power generation, metal mining, and waste incineration. Contrary to popular belief, the amount of Mercury in our environment and in the fish we eat is not increasing. In fact, there is evidence that the amount of Mercury in fish has remained the same - or even decreased in the past 100 years.

Mercury is toxic - it does not break down in the environment and can build up in living organisms. Traces of Mercury are present in all foods, including fish and seafood. In fish, Mercury converts into its most toxic form - Methyl Mercury. Methyl Mercury levels in fish accumulate in larger species - predatory fish such as Shark, Swordfish, Tuna, Marlin, Pike, Bass and Walleye. Consequently, individuals who consume fish and seafood may be exposed to varying levels of Methyl Mercury.

Research evaluating the health risks of Methyl Mercury toxicity - also known as Minamata disease - is contradictory and inconclusive. The World Health Organization has concluded that "the general population does not face a significant health risk from Methyl Mercury" in the fish we eat and that even fish species with the highest levels of Methyl Mercury don’t contain enough to be harmful. Conversely, other studies have found that health effects of Methyl Mercury toxicity do exist and that severity can depend on the level of exposure and age of the individual exposed. Possible symptoms include:
Tingling of the skin
Numbness
Lack of muscle coordination
Tremors
Tunnel vision
Slurred speech
Skin rashes
Abnormal behavior (such as fits of laughter)
Intellectual impairment
Coma
Death

Studies have also been done to document the prenatal affects of Methyl Mercury toxicity. These indicate that fetuses are at particular risk for neurological damage from Mercury exposure.

Polychlorinated Biphenyls (PCBs) refer to any one of 209 man-made chemicals that are similar in structure. PCBs were first manufactured as industrial materials (caulking compounds, cutting oils, lubricants, paint additives etc.) in the 1920’s. Concern over their environmental impact led the federal government to ban manufacture and import of PCBs and to phase out any PCBs used in current electrical applications.

Trace levels of PCBs are found in the environment and in the cells of animals. Higher concentrations are found in animals at the top of the food chain, including humans. The human average daily dietary intake of PCBs is thought to be less than 0.5 micrograms. People who eat large amounts of sports fish, wildlife or marine mammals may be exposed to higher dietary levels.

Adverse health effects caused by high-level exposure to PCBs include:
Severe acne
Swelling of upper eyelids
Discoloring of nails and skin
Numbness in arms and legs
Weakness
Muscle spasms
Chronic bronchitis
Problems related to the nervous system
Increased incidence of cancer, particularly liver and kidney

The American Heart Association (AHA) recommends that people eat at least two 3.5 oz servings of fish per week. Canada’s Food Guide recommends individuals consume a similar amount of fish per week, although slightly lower. Individuals with coronary heart disease may need to consume additional Omega-3 Fatty Acids. These people may be directed to take dietary supplements by their physician. No person should consume more than 3 grams of Omega-3 Fatty Acids per day from dietary supplements - unless under physician care.

The Monterey Bay Aquarium states that fish species considered high in Omega-3 Fatty Acids are those that provide at least 0.20 grams/day based a diet of 8 oz. per week. For a 7 oz. (two 3.5 oz. servings) diet per week this is 0.22 grams/day.

Despite conflicting evidence - various organizations have recommendations for the general public with respect to Mercury exposure. The US Environmental Protection Agency recommends that a person is exposed to 0.1 ug Mercury per kg body weight per day. This level corresponds to a blood Mercury level of 5.8 ug/L or 5.8 parts per billion. Commonly consumed fish species (Salmon, Cod, Pollock, Sole, Shrimp, Mussels, Scallops and canned Tuna) have Mercury levels far below this limit and are considered safe for consumption. Moreover, this level is far below what is necessary to result in neurological damage to adults - 200 ug/L is associated with a 5% risk.

Children, women of childbearing age, pregnant women and nursing mothers are advised to avoid eating fish species with the highest Mercury contamination levels e.g. Shark, Swordfish, King Mackerel.

Absolutely. Fish are considered an important part of a healthy diet and the benefits of consuming Omega-3 Fatty Acids far exceed the risk of Mercury or PCB exposure. However, as a precaution it is recommended to stay up-to-date on relevant health advisories and to not eat certain types of fish - too often.