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Cancer and Heart Disease from Fish are Suspect
 By Dr. Neil Nedley

Evidence is mounting that there may be a relationship between toxins and chronic human diseases such as cancer and heart disease that affect the developed na­tions in epidemic proportions. One piece of evidence involves the halogenated hydro­carbons, which is one class of compounds known to be biomagnified through the food chain.

Halogenated hydrocarbons also bioac­cumulate in humans. Elevated levels of these compounds have been found in the tissue of breast cancer patients. The re­searchers who identified this breast cancer linkage concluded, "These results, although preliminary, suggest a role for environmen­tally derived suspect carcinogens in the gen­esis [origin] of mammary [breast] carci­noma."

But the problems do not stop with can­cer. One investigator, in his review of the literature, found a "correlation between DDT plus DDE [two other halogenated hydrocarbons] in the blood and subjects who reported hypertension, arteriosclero­sis, and diabetes during subsequent years…"

Fish present some of the greatest con­cerns from the standpoint of biomagnification and bioaccumulation. They are not only contaminated with PCBs and various heavy metals such as mercury, but also with petroleum hydrocarbons and halogenated organic compounds. In a prominent medical textbook on environmental medi­cal issues, Dr. Kenneth Rosenman of Michigan State University stated, "The major on­going source of PCB exposure for the gen­eral population is the consumption of fish." Along with concerns about causing cancer, there is preliminary evidence link­ing both PCBs and dioxins with elevated blood cholesterol and triglycerides. Other data indicate that PCBs may affect male sperm counts and fertility.

Research suggesting that these contami­nants can harm the developing fetus has increased the stakes in the PCB issue even further.  Dr. Theo Colborn has pointed out that the research literature suggests that PCB present in the womb can "affect the developing nervous system of the embryo, fetus, and newborn." Recently, the New England Journal of Medicine grabbed head­lines when Drs. Joseph and Sandra Jacobsen further determined the developmental risks of PCB exposure. At 11 years of age, chil­dren with higher exposures to PCBs before birth showed impaired intellectual devel­opment. Although the children were not retarded, those with the highest PCB expo­sures were three times more likely to have low IQs and twice as likely to be at least two years behind in their reading compre­hension.

Acid Rain —A Pollution Agent for Toxic Metals

Accumulation of toxic metals in fish has recently caused particular concern in light of the problem of acid rain. Acid rain leads to acidified waters. This chemically altered water can then leach aluminum, manganese, lead, zinc, cadmium, and mercury out of bottom sediments or soil and into the wa­ter. Once these toxic metals are liberated, they find their way into the food chain and tend to bioaccumulate in fish tissues.

Warnings Advise Limited Fish Consumption

Even in scenic Maine, women of child-bearing age and children under eight are being urged not to eat fish from any pond or lake in Maine. Others are advised to re­strict their annual consumption to no more than six large fish or 22 small ones, all due to mercury content of the fish. Mer­cury ingestion in high levels can harm the development of human fetuses and children, and cause nervous system disorders and kid­ney damage in children and adults.

Michigan is the only other state to issue such a statewide warning. However, accord­ing to Martha Keating, an EPA staff scien­tist, other U.S. lakes and streams are just as hazardous as Maine's. The Boston-based Clean Water Action group has even gone on record stating that 90 percent of fresh­water fish caught in New England waters have contamination levels of mercury, lead, PCBs, or dioxin that are unsafe when con­sumed more that once a week. Although the group had collected significantly less data on saltwater fish, (so could not make a simi­larly sweeping statement), they did warn that the saltwater fish that were tested had high levels of PCB and mercury.

Probably the most widely publicized case of fish-related heavy metal poisoning had nothing to do with acid rain. It involved the tragic methyl mercury poisoning that resulted from eating fish from Japan's Minamara Bay. Japanese factory discharges of methyl mercury into the bay laid the foundation for the problem. The bionmagnification that occurred through the food chain exposed humans who ate the fish to dangerous organic mercury levels.

Known Health Problems from Contaminated Fish

 Perhaps nursing infants face the great­est danger from fish. One study found that pregnant mothers who consumed contami­nated Great Lakes fish experienced compli­cations with their newborns. These included alterations in birth size, gestational age, changes in neonatal health status, and effects that persisted into early Infancy. As a result of these risks, some have suggested that infants should not be breastfed because of the cancer risk. Although this may seem to make sense in our toxin-contaminated world, a better alternative may he to avoid the major sources of those toxins. Other research suggests that the bottle-feeding strategy may backfire. There is evidence that breastfeeding in and of itself decreases breast cancer risk. A 1994 study found that daugh­ters who were breast fed by their mothers had 25 percent less breast cancer. Breast­feeding has many other benefits as well.

 For the reader's convenience, a sum­mary of previously mentioned contamina­tion compounds found in fish is shown in Figure 8.

Benefits versus Risk of Eating Fish

 Some nutritionists would say that in certain individuals, risks of consuming fish are outweighed by the benefits of a diet high in omega-3 fats, particularly the mental and heart benefits. A diet high in omega-3 may also help rheumatoid arthritis and ulcerative colitis.

 Happily, there is a way to have the ben­efits of the omega-3 fatty acids without the risk of eating fish, fish oil, or expensive supplements. There is a way to bypass the cholesterol and toxins that come with the animal-derived omega-3. The way is so simple, yet it is not getting the publicity it deserves. We can obtain the benefits of omega-3 fatty acids from a plant fat called "linolenic acid." A certain variety of plant foods are high in omega-3 and can supply all of the body's needs for this essential fat. A list of plant foods high in omega-3 is pro­vided in Figure 9.

 It is possible for both meat-eaters and vegetarians to have a diet too low in omega-3 fats. For individuals who have depression or bipolar disorder, I recommend that each day they consume dishes that include some foods high in omega-3. In addition, I rec­ommend a home remedy that has helped a number of mentally ill patients to recover. A favorite recipe of many is included in Fig­ure 10.


Note the high content of omega-3 fats in the recipe. This is nearly equal to the daily amount consumed in fish oil by bipolar dis­order patients that produced promising re­sults in a Harvard Medical School study (9-6 g/day). Commenting on this study, Dr. Joseph Calabrese and colleagues at Case Western Reserve University in Cleveland, Ohio, call the trial a "landmark attempt in drug development for bipolar disorder." I would agree that it is a landmark study. However, no drugs were used, but omega-3 supplements only.

I recommend that at least one meal a day include foods high in omega-3.   I also recommend a minimum supplementation of 9 grams of omega-3 fats per day—ideally from plant sources.

Some nutritionists believe that it is not only important for the diet to contain suf­ficient omega-3 but to also emphasize foods that have a higher omega-3 to omega-6 fatty acid ratio. The average American consumes a diet many times higher in omega-6 than omcga-3. Appendix VIII lists foods with a more favorable omega-3 to omega-6 ratio.


DepressionFrom the book
Depression, the Way Out,
Nedley  Publishing, Ardmore, OK, 2001


Neil Nedley, M.D.,
Nedley Health Solutions
P. O. Box 1565
Ardmore, OK 73402

Toll-free: 1-888-778-4445
Phone: 1-580-226-8007
Fax: 1-580-223-2645