Home > Health Conditions > Toxins in fish oil

Toxins/Impurities or lack of in Fish & Fish Oil

In Supplements:

• Removing Toxic Mercury From Fish Oil While Retaining Beneficial Omega-3 Fatty Acids - Science Daily, 4/14/09
• Really? - The Claim - Fish Oil Supplements Can Contain Mercury - NYTimes.com, 3/23/09 - "The concern is a common one, but studies have found that most of the widely available supplements contain little or no mercury, dioxins or PCBs. For one thing, most companies use species of fish that are lower on the food chain, like cod and sardines, which accumulate less mercury. And many companies distill their oils to help remove contaminants"
• The Heart-Healthy Benifits of Omega-3 Fatty Acids - John Hopkins University School of Medicine, 6/05 - "Fish-oil supplements appear to have much lower levels of toxins than fish. In a study of 5 over the-counter fish-oil preparations, levels of PCBs and organochlorines were below the detectable limit in all of the supplements"
• Are Fish Oil Supplements Safer Than Eating Fish? - Life Extension Magazine, 10/05 - "analyzing five brands of fish oil supplements, researchers from Brigham and Women’s Hospital and Harvard Medical School in Boston found that levels of PCBs and organochlorine pesticides were below the detectable limit in all five brands tested"
• Analysis finds fish oil supplements safe - USA Today, 12/15/04 - "of 41 fish oil supplements tested, none were contaminated with mercury or PCBs ... the oil is distilled to filter out contaminants. Also the fish used to make pills tend to be younger and smaller than the fish we eat, meaning they have had less time to accumulate toxins"
• Fish oil suppliers turn to certifiers in the battle against contamination - Functional Foods & Nutraceuticals, 5/04
• Fish Oil Supplements: Too Toxic? - Dr. Weil, 8/21/02 - "she notes that results from a study published in 1998 indicate that tests of 44 different brands sold in 15 countries between 1994 and 1995 revealed appreciable quantities of organochlorines including PCBs and pesticide residues ... Ms. Johnson recommends them [omega-3] to those with autoimmune or inflammatory disorders, heart disease, diabetes, mental or emotional disorders, or insulin resistance ... Choose a brand that provides high levels of both EPA AND DHA in the least number of capsules"
• Fish Oil Supplements Pass Mercury Standards, But Lack Adequate Omega-3 Fatty Acids - Intelihealth, 11/29/01 - "Although none of the products tested positive for mercury (a poison sometimes found in fish), 30% of the products had lower levels of docosahexaenoic acid (DHA) than stated on their labels and 10% had lower levels of eicosapentaenoic acid (EPA). EPA and DHA are the two main fatty acids found in fish oil and are principle sources of omega-3 fatty acids. Omega-3 fatty acids are thought to provide many health benefits, including prevention of heart disease and treatment of pain associated with the early stages of rheumatoid arthritis"
• Product Review: Omega-3 Fatty Acids (EPA and DHA) from Fish/Marine Oils - ConsumerLabs.com, 11/20/01
• Letter - Mercury and Fish Oil Supplements - Medscape, 4/13/01 - "The following oils were tested: Twinlab Emulsified Super Max EPA ... Twinlab EPA New & Improved ... Twinlab Omege-3 Concentrate ... In conclusion, it appears that the independent testing and/or the quality control measures claimed by these companies are being done as far as potential mercury contamination is concerned. At the least, the amount of mercury in the fish used is so minimal as to be below the detectable limit by the method used.  In any event, the common brands tested appear to offer no mercury risk. While this is positive health news, it cannot be assumed that every brand is free of mercury"

In fish itself:

• Students chowing down tuna in dining halls are unaware of mercury exposure risks - Science Daily, 6/28/19 - "Researchers at UC Santa Cruz surveyed students outside of campus dining halls on their tuna consumption habits and knowledge of mercury exposure risks, and also measured the mercury levels in hair samples from the students. They found that hair mercury levels were closely correlated with how much tuna the students said they ate. And for some students, their hair mercury measurements were above what is considered a "level of concern." ... Nearly all fish contain some mercury, but tuna, especially the larger species, are known to accumulate relatively high levels of the toxic metal. Consumers are advised to eat no more than two to three servings per week of low-mercury fish (including skipjack and tongol tuna, often labeled "chunk light") or one serving per week of fish with higher levels of mercury (including albacore and yellow fin tuna) ... The researchers calculated that, to stay below the EPA reference dose, a 140-pound person could consume up to two meals per week of the lower-mercury tuna but less than one meal per week of the higher-mercury tuna"
• Fish, a Mediterranean source of n-3 PUFA: benefits do not justify limiting consumption - Br J Nutr. 2015 Apr;113(S2):S58-S67 - "By contrast, there is convincing evidence of adverse neurological/neurodevelopmental outcomes in infants and young children associated with methylmercury exposure during fetal development due to maternal fish consumption during pregnancy. Dioxins and polychlorinated biphenyls present in contaminated fish may also develop a risk for both infants and adults. However, for major health outcomes among adults, the vast majority of epidemiological studies have proven that the benefits of fish intake exceed the potential risks with the exception of a few selected species in sensitive populations" - Note:  If you look at the studies on the better fish oil supplements, nearly all of those toxins are filtered out.
• Fatty acids in fish may shield brain from mercury damage - Science Daily, 1/21/15 - "the new research indicates that this relation is far more complex and that compounds present in fish -- specifically polyunsaturated fatty acids (PUFA) -- may also actively counteract the damage that mercury causes in the brain ... These findings show no overall association between prenatal exposure to mercury through fish consumption and neurodevelopmental outcomes" - See fish oil supplements at Amazon.com.
• A Quantitative Synthesis of Mercury in Commercial Seafood and Implications for Exposure in the United States - Medscape, 12/18/12 - "U.S. Food and Drug Administration Hg Monitoring Program (FDA-MP) ... Mean Hg concentrations for each seafood item were highly variable among studies, spanning 0.3–2.4 orders of magnitude. Farmed fish generally had lower grand mean Hg concentrations than their wild counterparts, with wild seafood having 2- to12-fold higher concentrations, depending on the seafood item. However, farmed fish are relatively understudied, as are specific seafood items and seafood imports from Asia and South America. Finally, we found large discrepancies between mean Hg concentrations estimated from our database and FDA-MP estimates for most seafood items examined ... The FDA action level for MeHg of 1.0 ppm represents the threshold above which the agency can take legal action (e.g., removing the product from the marketplace) (FDA 2007). The U.S. EPA MeHg criterion of 0.3 ppm represents the fish tissue concentration that should not be exceeded for safe consumption of sport-caught fish in local waters based on average consumption (U.S. EPA 2001)"
• Farmed fish fed vegetable matter may have residual pesticides - Science Daily, 11/8/11 - "half of all the fish we eat comes from fish farms. The problem is that these fish are increasingly being fed vegetable matter, which could lead to a build-up of residual pesticides in them ... To protect consumers, there has to be a way to test fish bred in captivity for pesticide residues, but this has not been possible up to now"
• Mercury in Tuna Still a Concern, Consumer Reports Says - Medscape, 12/8/10 - "A woman of childbearing age who ate 2.5 ounces of any of the samples would be over the intake deemed safe by the Environmental Protection Agency (EPA)"
• Fish consumption and myocardial infarction: a second prospective biomarker study from northern Sweden - Am J Clin Nutr. 2010 Nov 3 - "fish also contains methylmercury, which may increase the risk of MI ... mercury (Ery-Hg) ... selenium (Ery-Se) ... (eicosapentaenoic and docosahexaenoic acids) in plasma phospholipids (P-EPA+DHA) ... sudden cardiac deaths (SCDs) ... Odds ratios for the third compared with the first tertile were 0.65 (95% CI: 0.46, 0.91) for Ery-Hg, 0.75 (95% CI: 0.53, 1.06) for Ery-Se, and 0.78 (95% CI: 0.54, 1.11) for P-EPA+DHA. Ery-Hg and P-EPA+DHA were intercorrelated (Spearman's R = 0.34). No association was seen for reported fish consumption ... High concentrations of Ery-Se were associated with an increased risk of SCD"
• Intake of marine n-3 fatty acids during pregnancy and risk for epilepsy in the offspring: A population-based cohort study - Epilepsy Res. 2010 Aug 24 - "Children born to mothers in the lowest (IRR=1.28, 95% CI: 0.98, 1.67) and highest (IRR=1.33, 95% CI: 1.02, 1.74) quintile of n-3 LCPUFA intake had an increased risk of epilepsy after adjustment for potential confounders compared to children born to mothers with an average intake ... Maternal deficiency of n-3 LCPUFA and a high intake of n-3 LCPUFA perhaps related to a high consumption of contaminated fish may be associated with an increased risk of epilepsy in early childhood"
• Fish Intake in Maternal Diet, Mercury Exposure May Affect Fetal Growth - Medscape, 9/14/09 - "small for gestational age (SGA) ... Compared with mothers who consumed less than 1 portion of canned tuna per month, those consuming 2 or more portions per week had newborns who weighed more (P for trend = .03) and had a lower risk of having infants who were SGA for weight"
• Mercury Low in Wild and Farmed Salmon - WebMD, 6/5/08
• Studies Link Other Ills to Mercury, Too - New York Times, 1/23/08 - "evaluated more than 100 patients who had vague, unexplained symptoms. Of them, 89 percent had mercury in their blood that exceeded the level considered acceptable by the Environmental Protection Agency ... The symptoms included memory lapses, hair loss, fatigue, sleeplessness, tremors, headaches, muscle and joint pain, trouble thinking, gastrointestinal disturbances and an inability to do complex tasks"
• High Mercury Levels Are Found in Tuna Sushi - New York Times, 1/23/08 - "Sushi from 5 of the 20 places had mercury levels so high that the Food and Drug Administration could take legal action to remove the fish from the market"
• Store-bought Freshwater Fish Contain Elevated Levels Of Mercury, Arsenic And Selenium - Science Daily, 11/7/07 - "mercury levels were 2.2 to 4.8 times higher in fish caught in the Canadian Lake Erie and available commercially than in fish caught near former iron and steel mills on the Allegheny and Monongahela rivers in Pittsburgh"
• Extracts Of Catfish Caught In Polluted Waters Cause Breast Cancer Cells To Multiply - Science Daily, 11/7/07
• Fish Farming's Growing Dangers - Time, 9/19/07
• One In Four New York City Adults Has Elevated Blood Mercury Levels - Science Daily, 7/23/07 - "A quarter of adult New Yorkers have elevated blood mercury levels, according to survey results released by the Health Department, and the elevations are closely tied to fish consumption"
• Fish-diabetes pollution link may boost supplements - Nutra USA, 4/13/07 - "the risk of pollutants from oily fish, such a methyl mercury, dioxins, and polychlorinated biphenols (PCBs) have led to some claims to reduce fresh fish intake, especially for pregnant women who may damage the development of their babies ... Most extracted fish oils are molecularly distilled and steam deodorised to remove contaminants ... The study, led by Professor Duk-Hee Lee observed a link between POP levels and diabetes"
• Fish pollutants' link to diabetes - BBC News, 4/12/07 - "An international team found high levels of persistent organic pesticides (POPs) in the blood correlated to insulin resistance"
• Maternal Fish Consumption, Mercury Levels, and Risk of Preterm Delivery - Medscape, 3/12/07 - "fish consumption is a major source of mercury exposure for pregnant women ... The greatest fish source for mercury exposure appeared to be canned fish, both because it was consumed more and, per meal, it was among the fish categories associated with the highest levels of mercury in maternal hair. The observed relationship between elevated mercury levels and increased risk of very preterm delivery is a new finding and requires caution in interpretation"
• Mercury Contamination Of Fish Warrants Worldwide Public Warning - Science Daily, 3/8/07 - "The health risks posed by mercury contaminated fish is sufficient to warrant issuing a worldwide general warning to the public"
• Seafood benefits outweigh risks - MSNBC, 10/17/06 - "Eating seafood twice a week is good for your heart and generally outweighs the risk of exposure to mercury and other dangerous contaminants"
• How Dangerous Is Farmed Salmon? - Dr. Weil, 8/1/06
• Higher mercury in imported tuna - MSNBC, 7/11/06
• Canned Tuna: Avoid if Pregnant? - WebMD, 6/5/06
• Benefits Of Eating Seafood Outweigh Risks - Science Daily, 2/24/06 - "Though some species of fish around the world's are likely to be contaminated with mercury, PCBs and other toxins, the benefits of eating seafood continue to outweigh the risks, a panel of scientists recently said at the annual meeting of the American Association for the Advancement of Science"
• Study: 20% Of Women 16-49 Have High Mercury Levels - cbs2chicago.com, 2/8/06 - "Twenty percent of women ages 16 to 49 have mercury levels that exceed the EPA's recommended limit ... the greatest single factor influencing mercury exposure was the frequency of fish consumption"
• Have a Daily Dose of Omega-3 - US News, 12/26/05 - "Farmed salmon are raised on fish oil pellets derived from local fish, which are often contaminated with cancer-causing PCB s. The most recent study, in the November issue of the Journal of Nutrition, reports that contaminant levels in farmed salmon from certain regions increase the risk of cancer enough to outweigh benefits"
• Stick To Wild Salmon Unless Heart Disease Is A Risk Factor, Risk-Benefit Analysis Of Farmed And Wild Fish Shows - Science Daily, 12/26/05 - "On the one hand, farmed salmon has more heart-healthy omega-3 fatty acids than wild salmon. On the other hand, it also tends to have much higher levels of chemical contaminants that are known to cause cancer, memory impairment and neurobehavioral changes in children"
• Benefits of Fish Outweigh Mercury Risk - WebMD, 10/19/05 - "If you are not going to become pregnant, you should eat fish. Mercury is not an issue for you"
• Viewpoint: Mercury Level and Fish: Risks vs Benefits - Medscape, 10/17/05
• N.Y. Times Calls Wild Salmon a Gamble for Consumers - Vital Choices, 4/22/05
• Mercury in Commercial Fish - Medscape, 3/21/05
• Fish Oil Supplements May Be Safer Than Eating Fish - Medscape, 1/28/05 - "The authors estimate that compared with fish oil supplementation, regular consumption of fish from the Great Lakes would expose humans to at least 70 times more PCBs and 120 times more OC pesticides"
• A Better Pink Fish? - Dr. Weil, 9/2/04
• Too Much Mercury in Freshwater Fish? - Dr. Weil, 8/31/04 - "To avoid mercury contamination and still derive the nutritional benefits of eating fish, I recommend sticking to such cold water fish as wild Alaskan salmon, sardines, herring, and – if you can get it – black cod, also known as sablefish"
• Fish Advisories Rising Due to Mercury Risks - WebMD, 8/25/04 - "Eating fish from more than a third of the country's lakes and a nearly quarter of its rivers may not be a healthy idea ... the threat of mercury contamination is rising in American waters"
• Fishing for Fish Information? - Dr. Weil, 8/19/04 - "My favorite fish is wild Alaskan salmon, which is delicious, contains plenty of omega-3s, and is relatively toxin-free ... Avoid farmed salmon (also called Atlantic salmon)"
• Low Levels of Flame Retardant Found in Salmon - WebMD, 8/11/04
• Traces Of Fire Retardant Found In Salmon - Intelihealth, 8/11/04
• Farmed and wild fish in the prevention of cardiovascular diseases: assessing possible differences in lipid nutritional values - Nutr Metab Cardiovasc Dis. 2004 Feb;14(1):34-41 - "Provided that they are raised under appropriate conditions, the nutritional content of farmed fish is at least as beneficial as that of wild fish (particularly in terms of the prevention of cardiovascular diseases), and they also have the advantages of freshness and apparent non-toxicity"
• FDA Issues New Tuna Limits for Women - WebMD, 3/19/04
• Recommended fish intake is potentially dangerous due to high methylmercury content of certain fish - Asia Pac J Clin Nutr. 2003;12 Suppl:S67 - "Recommendations to limit fish intake to prevent MeHg toxicity are in conflict with recommendations to prevent CHD. Species and origin of fish needs to be taken into account to prevent MeHg toxicity"
• Farm Salmon More Contaminated Than Wild - WebMD, 1/8/04 - "The most highly contaminated salmon came from farms in Europe, the study shows -- especially Scotland. North American and South American salmon farms had a lot less -- but still more than wild salmon" - On 1/8/03, the CBS Evening News had some expert that claimed that you should not eat farmed salmon more then once per month.
• FDA to Warn Pregnant Women to Limit Tuna - WebMD, 12/11/03
• Fish Intake Is Positively Associated with Breast Cancer Incidence Rate - J Nutr. 2003 Nov;133(11):3664-3669 - "higher intakes of fish were significantly associated with higher incidence rates of breast cancer. The association was present only for development of ER+ breast cancer"
• Mercury in Fish May Not Be Toxic - WebMD, 8/28/03
• How Safe Is Salmon? - Time, 8/11/03 - "EWG found that store-bought salmon, most of which is farmed, contained 16 times the PCB levels of salmon caught in the wild. The Environmental Protection Agency considers these levels a health hazard, and if they were found in wild salmon would recommend eating the fish no more than once a month"
• Is Your Salmon Safe? - WebMD, 7/31/03 - "bought 10 salmon filets in grocery stores in Washington, D.C.; Portland, Ore.; and San Francisco. Lab analysis showed "high" PCB levels in seven of the 10 samples"
• How much mercury is in the fish you eat ? - MSNBC, 4/4/03
• Something Fishy With Seafood? - CBS News, 2/25/03 - "Studies show that mercury found in some fishes can be unhealthy and dangerous for pregnant women. But experts say little has been done to warn those at risk ... mercury in the body can result in impaired coordination, blurred vision, tremors, irritability, memory loss and behavioral or intellectual problems"
• Heart Risks Tied Directly To Mercury In Nine-Country Study - Doctor's Guide, 12/2/02 - "High mercury content in some fish may diminish the cardioprotective effects associated with consumption of omega-three fatty acids fish ... While the toenail mercury level was directly associated with risk of myocardial infarction, the fish oil level was inversely associated with this risk"
• How Much Tuna Can You Eat Each Week? - Time, 11/18/02 - "25 lbs. -- 1 oz. (1 tablespoon) ... 50 lbs. -- 2 oz ... 75 lbs. -- 3 oz ... 100 lbs. -- 5 oz ... 125 lbs. -- 6 oz. (1 can) ... 150 lbs. -- 8 oz ... 175 lbs. -- 9 oz ... 200 lbs. -- 10 oz"
• Hold The Mercury - CBS News, 11/5/02 - "89 percent of patients with a fish-heavy diet had blood-mercury levels exceeding that deemed safe by the government"
• Study Records Elevated Mercury - Intelihealth, 10/19/02 - "A study of Californians who loaded their lunch and dinner menus with fish shows 89 percent wound up with elevated mercury levels in their bodies ... Of that group, 63 people had blood mercury levels more than twice the recommended level and 19 showed blood mercury levels four times the level considered safe. Four people had mercury levels 10 times as high as the government recommends"
• Fish-mercury risk underestimated - CNN, 4/12/01 - "millions of pregnant women and their fetuses are at risk of serious health problems from exposure to mercury in fish ... shark, swordfish, king mackerel and tilefish not be eaten by pregnant women and women of childbearing age who might become pregnant. It also recommended that nursing mothers and young children steer clear of these fish"