Misunderstanding involved with consuming marine organisms

When I first started studying marine biology at University of Hawai‘i at Mānoa I didn’t eat very much fish. I had heard all the hype about mercury poisoning and the potential health risks and was not interested in getting sick. After taking an oceanography class on fisheries I found out that this was a very common misconception. The fact is eating fish has unbelievable effects on your health. Fish is one of the healthiest things you could put into your mouth, and by not eating fish you could be potentially causing harm to your body. “There are no confirmed cases of mercury poisoning from eating tuna or open ocean fish” (Bienfang and Rosenthal) these facts completely blew my mind. Throughout my life I have heard so much talk about how terrible the effects of mercury poisoning from eating fish are. After completion of this course I was now well aware that eating fish was actually better than not eating fish and began enhancing my diet with fish as often as possible. Since then I have still been hearing non-stop talk about how fish are BAD and we shouldn’t eat too much because we might get sick, so I decided to set everyone straight and share my knowledge of the subject with the world.


Why is it healthy?

I hope everyone is already aware that protein is a major component of the human diet and is absolutely necessary for survival. Proteins do pretty much everything in the human body; they make cells, repair cells and make other proteins. Without proteins life would not be possible, they are required to see, feel, hear, and move. Different sources of protein are ranked on a scale of quality based on the amount of amino acids they contain and the % of calories that come from the protein in them. “fish protein utilization efficiency is 82%-83%”(Bienfang and Rosenthal) Seafood is the highest ranking on this scale due to the fact that it contains all 9 of the essential amino acids and has the highest percent of calories from protein. Seafood is “an excellent source of protein which accounts for more than 40% of the calories in the fish for comparison, protein accounts for only 15%, 25%, and 35% of the calories in pork, chicken, and eggs.” (Bienfang and Rosenthal) The only other proteins that are slightly close are found in eggs, other meats and vegetables simply cannot compare to the quality of seafood. Fish also contains omega 3 fatty acids which are extremely healthy and necessary in the human body, but cannot be made in the human body and must be consumed. Fish oil pills are available and are healthy, but do not have all the same health benefits as simply consuming fish does.

Disease or health condition Strong evidence of significant health benefits Promising preliminary results
Coronary heart disease a
High blood pressure a
Irregular heart beat
Diabetes a
Rheumatoid arthritis a
Asthma a
Bowel cancer a
Crohn’s disease a
Neural development a








Why isn’t it harmful?

Consuming fish is talked about as harmful due to the mercury content in fish. Mercury is a metal element that is known to be toxic. Mercury poisoning is known to have harmful effects including coma and death. So the fact that fish has mercury in it seems to be a reasonable scare and it is understandable why people are afraid to eat fish. Mercury is toxic when the amount is high enough, but can be harmless when the amount is low enough. The fact is no cases of mercury poisoning have been caused from eating open ocean fish. Selenium is a nonmetallic element which is also found in fish, and is known to counteract the mercury content in fish. Yellowfin tuna is known to have high levels of selenium which protects against mercury poisoning.


Pregnancy and small children

The FDA and EPA have put out warnings to prevent pregnant women and small children from getting mercury poisoning. Unborn babies and young children are more susceptible to the harmful effects of mercury.  The FDA warning had 3 warning for pregnant women “1. Do not eat shark, swordfish, king mackerel, or tilefish because they contain high levels of mercury. 2. Eat up to 2 meals of fish per week. 3. Limit tuna consumption to one meal per week.” (FDA and EPA 2004) Then the Harvard center for risk analysis states “this advisory is only for pregnant women and young children, it is not for general consumer. The majority of consumers can benefit from eating more fish; avoiding fish may cause an increased risk of heart disease.” (Harvard center for risk analysis)


Real risks

Due to the great health benefits from consuming fish, the real problem is that some people may be scared to eat fish and become malnourished due to the lack of the nutrients found in fish. This is particularly important in unborn babies and young children. Omega fatty acids are required for proper brain development and in these crucial growing stages of children’s lives, it is necessary to supplement development in every way possible. Improper balance of these can “lead to overproduction of hormone-like compounds called eicosanoids, and this condition can lead to the development of atherosclerosis (thickening of blood vessel walls due to deposition of fat and cholesterol) heart attacks and possible other health problems.(Lands, 1986) “ mercury advisors may scare women to avoid eating fish and place babies at risk. Babies deprived of healthy fish oils can effect brain and vascular development” (Bienfang and Rosenthal) “ the benefits of healthy fish oils to babies are known and widely accepted and the potential harmful effects of low levels of mercury from open ocean fish are uncertain, undocumented, and hypothetical” (Bienfang and Rosenthal)


Developing countries

Some countries that are poverty stricken and malnourished due to lack of resources available could greatly benefit from the health boosts from consuming fish.

“An improvement to the quality protein available to persons in developing countries would undoubtedly help to alleviate protein deficiency problems. Incorporation of those fish and or fish products into the diet could obviously serve that purpose” (Bienfang and Rosenthal) “in the case of developing countries partial substitution of fish for other meats could greatly improve the ratio of omega 3 to omega 6 in the diet and hence reduce the incidence of atherosclerosis and heart attacks. “(Bienfang and Rosenthal)


Eating whales and dolphins

This information is all based on open ocean fish. This means fish, not marine mammals. Some marine mammals have high levels of mercury and extremely low levels of selenium to counter them. Consuming marine mammals could result in mercury poisoning. “Pilot whales are marine mammals, not fish, and consuming them could result in mercury poisoning” (Bienfang and Rosenthal)


Some studies to prove it

In 2007 ALSPAC ( AVON LONGITUDINAL STUDY OF PARENTS AND CHILDREN) which is the largest study to date on fish consumption effects, tested over 8,000 women and children pairs and showed children’s test scores increased with increasing consumption of fish by mothers during pregnancy. They showed regardless of dietary mercury, eating fish is good for babies. Children born to women that ate two fish meals or less per week, which is EPA/FDA guidance, were more likely to be in the lowest 25% of cohert group for verbal IQ and other developmental scores.

(Avon Longitudinal Study of Parents and Children (Hibbeln, et al., 2007 Lancet))

National healthy mothers, healthy babies coalition states that pregnant mothers should eat fish. They recommend mothers to eat at least 2 meals per week (12 oz) to ensure proper brain development, it also recognizes selenium appears to protect against the toxic effects of mercury. (http://www.sciencedaily.com/releases/2007/10/071004133313.htm)

The Faroe Islands study found subtle learning defects in children correlated with umbilical cord mercury levels. Many misconceptions have developed based on this study. This study is used to convince people to limit fish consumption. The problem with this study is pilot whales are not fish. During this study women ate high amount of pilot whale during their pregnancy. Pilot whale has high amounts of mercury and low amount of selenium that are not enough to counteract it. (Steuerwald et al., 2000. Maternal seafood diet, methyl mercury exposure and neonatal neurological function. J Pediatrics 136:599-605.)



This is a Faroe islands event, these are whales. Not fish.

The Seychelle islands study was done with fish consumption very high, 12 meals per week, with fish eaten including skipjack, yellowfin, wahoo, jacks and barracuda (ave mercury 0.3ppm). No whale meat was consumed during this study and there was no evidence of negative health effects in children tested up to age 9. (Myers et al., 2003. Prenatal methyl mercury exposure from fish consumption in the Seychelles child development study. Lancet 361: 1686-1692. )


So now we know

“The health benefits of eating fish greatly outweigh the possible risks (rimm et al (Harvard school of public health)) “there has never been a case of mercury poisoning from eating pelagic fish, including tuna, swordfish and other” (Bienfang and Rosenthal) Whale meat and dolphin meat have high levels of mercury and low levels of selenium and are therefore dangerous to eat. “Selenium is an essential antioxidant; it has anti-cancer effects and is known to promote immune system function. It is known as a metal detoxification (ex: mercury)” (Bienfang and Rosenthal)

-Brittney Kosar



Agency for Toxic Substance and Disease Registry

Avon Longitudinal Study of Parents and Children (Hibbeln, et al., 2007 Lancet)

Bienfang, P. K., H. Trapido-Rosenthal, and E. A. Laws. 2011. Magnification of Risks: Bioaccumulation/Biomagnifications in Food Chains. 25pp. In: Encyclopedia of Sustainability Science and Technology. R. A. Meyers (Ed.), Springer Science + Business Media LLC, doi:10.1007/978-1-4419-0851-3.

Choy et al., 2009. The influence of depth on mercury levels in pelagic fishes and their prey.  www.pnas.org/cgi/doi/10.1073/pnas.0900711106

FDA and EPA. 2004. What you need to know about Mercury in Fish and Shellfish. March 2004. www.cfsan.fda.gov/~dms/admehg3.html

Ganther et al., 1972 Selenium: relation to decreased toxicity of methylmercury added to diets containing tuna. Science 175: 1122.

Kaneko, JJ and NVC Ralston 2007. Selenium and Mercury in Pelagic Fish in the Central North Pacific Ocean near Hawaii. Biological Trace Element Research 119 (3): 242-254. (NOAA Award No. NA05NMF4521112)

Lands, W. E. M., 1986. Fish and Human Health. Academic Press, New York.

Myers et al., 2003. Prenatal methyl mercury exposure from fish consumption in the Seychelles child development study. Lancet 361: 1686-1692.

NRC. 2000. Toxicological effects of methylmercury. National Academy Press.

Plessi et al., 2001. Mercury and Selenium Content in Selected Seafood. JOURNAL OF FOOD COMPOSITION AND ANALYSIS. 14, 461}467. doi:10.006/jfca.2001.1003.

Raymond et al., Mercury and selenium interactions and health implications

Rimm et al. (Harvard School of Public Health)

Steuerwald et al., 2000. Maternal seafood diet, methyl mercury exposure and neonatal neurological function. J Pediatrics 136:599-605.


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