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Should patients be concerned about taking fish oil supplements?

Heart, Stroke, General, Infant and Children | May 17, 2016 | Author: The Super Pharmacist

Children, heart, general, infant, Stroke

Should patients be concerned about taking fish oil supplements?

Long chain polyunsaturated fatty acids found in fish, also-called omega-3 fatty acids, provide a number of impressive cardiovascular benefits. Omega-3 fatty acids improve blood cholesterol and triglyceride levels, blood pressure, arrhythmia, and heart rate thus reducing the risk of atherosclerosis, coronary heart disease, acute coronary syndrome, and sudden cardiac death. Omega-3 fatty acids also appear to be important for normal brain and nervous system development in fetuses and infants.

While fatty fish are a good source of omega-3 fatty acids, it is generally more practical for people to consume fish oil supplements that contain eicosapentaenoic acid (EPA, 20:5n-3), and docosahexaenoic acid (DHA, 22:6n-3) instead of large amounts of fresh fish.

There has been some concern that fatty fish and, indeed, fish oil supplements may contain toxins such as heavy metals that may cause their own health problems. While existing laws prevent the importation and sale of contaminated products, the amount of scrutiny that supplements receive is usually far less than those of prescription or even over-the-counter medications. Thus, in many cases, it is ultimately up to the consumer to assess the safety of fish oil supplements.

Complementary medicines in Australia

Complementary medicines in AustraliaFish oil supplements are considered complementary medicines in Australia. It takes a risk-based approach when considering complementary medicines, separating medicines into two tiers - high risk and low risk. 

Higher risk medicines must be listed on the Australian Register of Therapeutic Goods (ARTG)

Lower risk medicines, such as fish oil supplements, may or may not be registered on this list.

Approximately 2400 compounds containing fish oil are listed in the ARTG.

Complementary medicines, including fish oil supplements, list ARTG must comply with certain composition and purity requirements.

Current standards for fish oil supplements

Compositional guidelines regarding fish oil supplements have been laid out by the Australian government, specifically the Therapeutic Goods Administration under the auspices of the Australian Department of Health.

  • Natural fish oil must contain at least 10% EPA and DHA combined. Total omega-3 fatty acids must exceed 14%.
     
  • Likewise, there are maximum acceptable levels for heavy metals and potentially toxic substances including lead, arsenic, cadmium, and mercury. The acceptable level of arsenic is less than or equal to one part per million (ppm), while the acceptable level of the other three elements are equal to or less than 0.5 ppm.
     
  • Fish oil supplements must also conform to statutory maximums concerning pesticides. The acceptable levels of pesticides are must follow European Pharmacopeia guidelines, specifically Ph Eur method 2.8.13.
     
  • Fish tend to absorb and concentrate some toxins, namely polychlorinated dibenzo-para-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs). Regulations require manufacturers of fish oil supplements to keep the concentration of these toxins below stringent maximum acceptable values. The maximum acceptable values for these substances are on the level of one part per billion (ppb) or 1 part per trillion (ppt).

Can there be a minimum safe level of toxins?

Consumers tend to look at these guidelines in one of two ways. The acceptable levels set by regulatory agencies are quite low and are considered to be generally safe. On the other hand, many people may be reasonably concerned that their fish oil supplements contain any heavy metal or toxic substance, no matter how low.

Can there be a minimum safe level of toxins?Remember these guidelines are maximum values. It may be the case that a fish oil supplement contains no detectable amounts of these contaminants. The guidelines stipulate that they may not exceed these amounts. 

Keep in mind, also, only a handful of large, predator fish contain significant amounts of mercury. These fish include shark, swordfish, king mackerel, tilefish, and albacore tuna.

Fish oil supplements are largely produced from less expensive fatty fish and, as such, commercially available fish oil capsules contain little to no mercury. 

Indeed, since heavy metals tend to bind to fish proteins rather than the fatty acid component, fish oil supplements likely contain less mercury than the corresponding amount of fish.

The same is true for PCBs and dioxins. Fish oil capsules contain extremely small amounts of these substances, far less than the whole fish themselves.

Healthy individuals are unlikely to experience any negative health effects from the low levels of these substances, even when fish oil supplements are taken in therapeutic or slightly supratherapeutic doses.5

Pregnant and nursing mothers

One group of individuals who may be particularly cautious when it comes to fish and fish oil consumption are pregnant and nursing mothers.

Mercury can cross the placenta and may be found in breast milk, though in extremely small amounts. Women may be concerned that they are exposing their unborn and newborn children to heavy metals, such as mercury and not consume enough omega-3 fatty acids in their normal diet to provide sufficient amounts during gestation and breast-feeding.

Fish oil supplements may be a better source of omega-3 fatty acids, such as EPA and DHA, and likely to contain far lower concentrations of mercury and other toxins than predator fish themselves.

Experts agree that pregnant and nursing mothers should eat a minimum amount of fish during pregnancy and breastfeeding, there is no clear evidence that children born of mothers who take fish oil supplements during pregnancy have improved nervous system development. This explains why governmental regulatory agencies suggest eating low mercury fish rather than taking fish oil supplements during pregnancy and breastfeeding.

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References

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Erkkila AT, Lichtenstein AH, Mozaffarian D, et al. Fish intake is associated with a reduced progression of coronary artery atherosclerosis in postmenopausal women with coronary artery disease. Am J Clin Nutr. Sep 2004;80(3):626-632.

Geleijnse JM, Giltay EJ, Grobbee DE, et al. Blood pressure response to fish oil supplementation: metaregression analysis of randomized trials. J Hypertens. Aug 2002;20(8):1493-1499.

Mozaffarian D, Lemaitre RN, King IB, et al. Plasma phospholipid long-chain omega-3 fatty acids and total and cause-specific mortality in older adults: a cohort study. Ann Intern Med. Apr 2 2013;158(7):515-525.

Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. Oct 18 2006;296(15):1885-1899.

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https://www.tga.gov.au/compositional-guideline-fish-oil-natural.

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Jimenez B, Wright C, Kelly M, et al. Levels of PCDDs, PCDFs and non-ortho PCBs in dietary supplement fish oil obtained in Spain. Chemosphere. Feb 1996;32(3):461-467.

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