Fish – Good or Bad

I wrote this as a news story for the site.

Fish – Good or Bad

We have all been told by our grandmothers that fish is good for us being the “food for the brain”. However women who are nursing, pregnant or expecting to get pregnant must be especially careful to avoid contaminated fish.

Polychlorinated biphenyls (PCBs) and mercury have the worst health effects on developing foetuses, infants and children. PCBs are a large group of industrial chemicals with a common structure. They are oily liquids or solids, clear to light brown in colour, and have no smell or taste. PCBs do not occur naturally in the environment. Along with methylmercury, they pose the greatest health concern in eating fish and are one of the main chemical contaminants that have been found in fish.

Mothers who eat contaminated fish unknowingly ingest these toxins and pass them along to their children. PCBs can cause children to develop and learn more slowly. Mercury can affect the development of the nervous system, hindering a child’s ability to walk and talk. It was as long as a decade ago, Drs. Joseph and Sandra Jacobsen of Wayne State University reported that exposure to low levels of PCBs disrupted foetal brain development, and caused neurological abnormalities and learning disabilities, including memory problems, in affected children. Mercury can affect the development of the nervous system, hindering a child’s ability to walk and talk.

There are a few ways to avoid eating contaminated fish:

  • Choose smaller fish. Generally, panfish and fish just over the legal size to be caught will have fewer chemicals.
  • Choose lean fish. Panfish, brook trout and brown trout that live in streams and rivers tend to be low in fat. Small walleye, northern pike and bass, especially those that are just legal size, also tend to have fewer chemicals. Carp and catfish are higher in fat and usually have more chemicals.
  • Choose fish that don’t eat other fish. Large predator fish, especially large walleye, northern pike, muskie, bass and lake trout tend to have more chemicals.
  • Avoid swordfish and shark. They often have very high mercury levels.

Don’t cut out fish altogether though.

Fish has a great deal of other health benefits.

  • Heart Disease. Studies have shown that regular fish intake — about once a week — can significantly reduce the risk of heart disease. In a 1998 study, researchers found that men who ate fish at least once a week reduced their risk of sudden cardiac death by 52 percent, compared to men who ate fish less than once a month.
  • Blood Pressure. Johns Hopkins University’s Dr. Lawrence J. Appel found that omega-3 fatty acids, the kind found in salmon and mackerel, can help lower blood pressure in people with untreated high blood pressure. There have also been numerous studies confirming the benefits of dietary fish intake combined with weight loss to lower blood pressure.
  • Arthritis. A study by Brigham and Women’s Hospital in Boston found that fish oil may help reduce the pain and inflammation of rheumatoid arthritis. Especially helpful are cold-water fish like salmon, cod and even sardines. Shellfish weren’t proven to be very effective.
  • Cancer. There is some evidence to indicate that fish intake may protect against breast cancer, and, based on animal models, fish oil seems to have inhibitory effects against several other types as well –

    - including cancer of the colon, skin, pancreas, prostate, lung and larynx.
  • Weight loss. Several studies have found the correlation between regular fish intake, in addition to a healthy diet, and weight loss. Fish rich in omega-3 fatty acids, such as tuna or salmon, can help in weight loss, lower cholesterol and improve overall health, according to researchers and dieticians.
  • Depression. Though several studies have confirmed the link between fish intake and depression risk, it is unclear exactly what causes the lowered depression risk. Some experts think that fish oil blocks the abnormal signaling in the brain that is present in mania and depression.
  • Vision. Studies show that a moderate intake of fish — one to three servings a month — may protect against age-related macular degeneration (AMD), the leading cause of irreversible blindness in the United States. AMD usually affects people over age 60 and affects central vision — so although victims of the disease don’t usually go blind, the condition complicates daily activities such as reading and driving.


Fish has many health benefits but there are a few risks. You certainly should eat fish once or twice a week but do avoid river fish especially the predatory ones and also avoid swordfish and shark due to there higher mercury levels. Stick to non predatory sea fish such as cod, herrings and sardines whilst pregnant and nursing.

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