On The Fence About Eating Fish? Worried About Mercury?

March 4th, 2016

Plate of Fried Salmon fillet and spices

If you have reduced or eliminated fish intake due to concerns about mercury it’s probably a big mistake.  The government and alleged experts just got it all wrong!

Most people have read about the multiple health benefits of eating seafood. Many of these benefits are derived from the essential fatty acids like EPA (eicosapentanoic acid) and DHA (docahexanoic acid) which are found in higher amounts in fatty fish like salmon, mackerel, herring, anchovies and lake trout. In addition, seafood is an excellent source of quality protein and vitamin D.


Just some of the reported benefits of fish include:
·         Heart health
·         Brain health,
·         Mental health,
·         Eye health
·         Reduced risk of auto-immune diseases

Fish may increase grey matter in the brain and protect it from age-related deterioration and may reduce the risk of certain types of cancer. The essential fatty acids in fish are very anti-inflammatory and systemic inflammation is fundamental to the development and progression of most chronic degenerative diseases.

In my opinion, the consumption of the right types of fish and vegetables are the foundational components of a life extending-longevity diet.

The question is, “How did we ever get to the point where we thought it might be a good idea to limit fish consumption because of mercury levels?”

To understand how fish consumption and mercury content incorrectly became something to be concerned about and how this “misguided information and subsequent poor advice” (which by the way, the FDA has subsequently reversed) came about we have to go back over 12 years ago to a study that was published about the effects of maternal fish consumption on children born in the Faroe Islands, a group of islands halfway between Iceland and Norway.1

The study found that maternal consumption of seafood had a modest negative effect on young children’s brain and possibly heart function.  No negative effects of mercury in seafood on adults were stated.

Based upon these results, the National Research Council set standards for limiting seafood consumption in pregnant women and in 2004 the EPA and FDA released guidelines proposing that women wanting to become pregnant or already pregnant limit their fish consumption to 12 ounces a week (28.4 grams per ounce for those using metric).

These guidelines-warnings caused millions of young women to severely cut back on fish consumption, if not eliminate it completely, thinking they were protecting their unborn children.  This reaction to these guidelines was probably not protective and very possibly harmful.

As it turns out, the maternal seafood consumption in the Faroe Islands was 85% pilot whale and this fish was known to have excessively higher levels of mercury and toxins than most any other sources of ocean seafood and was pretty much a phenomenon related to this culture and had little or no application to the types of seafood being eaten by the rest of the world.

An interesting side-bar is that the Harvard Chan School was involved in this study. The take-away is that studies can be misleading, confusing and potentially dangerous if reviewed in a vacuum and not put into proper perspective, especially when contradictory studies exist (no matter how prestigious the reputation of the researchers.)

The media and ecology groups ran wild publicizing and writing about this misleading study, and what was incorrectly aimed only at reducing seafood consumption in pregnant or soon to be pregnant women quickly spread to include everyone.

Large numbers of pregnant women either reduced seafood consumption or eliminated it completely.  We will discuss how these pregnant women may have inadvertently negatively impacted the brain development of their soon to be born children by reducing seafood consumption.

Then 10 years later (2014) based upon a review of existing data and two new studies demonstrating the substantial health/brain benefits of fish consumption by pregnant women on the brain development of their newborns, the FDA reversed it’s 2004 guidelines and released the following proposed draft of new guidelines:

June 10, 2014 – Release

The U.S. Food and Drug Administration and the U.S. Environmental Protection Agency today issued draft updated advice on fish consumption. The two agencies have concluded pregnant and breastfeeding women, those who might become pregnant, and young children should eat more fish that is lower in mercury in order to gain important developmental and health benefits. The draft updated advice is consistent with recommendations in the 2010 Dietary Guidelines for Americans.

Previously, the FDA and the EPA recommended maximum amounts of fish that these population groups should consume, but did not promote a minimum amount. Over the past decade, however, emerging science has underscored the importance of appropriate amounts of fish in the diets of pregnant and breastfeeding women, and young children.

“For years many women have limited or avoided eating fish during pregnancy or feeding fish to their young children,” said Stephen Ostroff, M.D., the FDA’s acting chief scientist. “But emerging science now tells us that limiting or avoiding fish during pregnancy and early childhood can mean missing out on important nutrients that can have a positive impact on growth and development as well as on general health.”

An FDA analysis of seafood consumption data from over 1,000 pregnant women in the United States found that 21 percent of them ate no fish in the previous month, and those who ate fish ate far less than the Dietary Guidelines for Americans recommends—with 50 percent eating fewer than 2 ounces a week, and 75 percent eating fewer than 4 ounces a week. The draft updated advice recommends pregnant women eat at least 8 ounces and up to 12 ounces (2-3 servings) per week of a variety of fish that are lower in mercury to support fetal growth and development.

“Eating fish with lower levels of mercury provides numerous health and dietary benefits,” said Nancy Stoner, the EPA’s acting assistant administrator for the Office of Water. “This updated advice will help pregnant women and mothers make informed decisions about the right amount and right kinds of fish to eat during important times in their lives and their children’s lives.”

Before issuing final advice, the agencies will consider public comments, and also intend to seek the advice of the FDA’s Risk Communication Advisory Committee and conduct a series of focus groups.

The public can provide comment on the draft advice and the supplemental questions and answers by submitting comments to the Federal Register docket or by participating in any public meetings that may be held. The comment period will be open until 30 days after the last transcript from the advisory committee meeting and any other public meetings becomes available. The dates of any public meetings, as well as when the public comment period will close, will be published in future Federal Register notices at www.federalregister.gov.

We (the Food and Drug Administration and the Environmental Protection Agency) are issuing this advice to encourage women to eat recommended amounts and types of fish. Recent reports show many pregnant women in the United States are not consuming fish in amounts recommended by the Dietary Guidelines for Americans 2010. This advice is being issued now to encourage women who are pregnant (or may become pregnant) or breastfeeding and young children to eat more fish and to eat a variety of fish from choices that are lower in mercury. The Dietary Guidelines for Americans 2010, the federal government’s evidence-based nutritional guidance to promote healthy eating, now recommends that “women who are pregnant or breastfeeding consume at least 8 and up to 12 ounces of a variety of seafood per week, from choices lower in methyl mercury.” 

There is longstanding evidence of the nutritional value of fish in the diet. Fish contain high quality protein, many vitamins and minerals, omega-3 fatty acids, are mostly low in saturated fat, and some fish even contain vitamin D. The nutritional value of fish is especially important during growth and development before birth, in early infancy for breastfed infants, and in childhood.

Two important studies that caused the guidelines to be corrected were done in the Seychelle Islands and Barcelona Spain.

The Barcelona study found that pregnant women who ate 3-4 servings of fish (21 ounces weekly or approximately 600 grams) on a weekly basis may benefit the brains of their  to be born children and may even reduce the risk of autism.  The study tracked 2000 women from their first trimester up until their kids turned 5 years old. The researchers found that the children whose mothers consumed fish at the level had almost 3% higher IQ’s than those children whose mothers consumed less.  There were NO signs that mercury had any negative effect on these children.2

The Seychelle Islands study was published in The American Journal of Epidemiology.  This study was carried out by scientists from the University of Rochester Medical School. The researchers continue to monitor multiple areas of brain and cognitive function of these children every few years and to date; they are healthy and show no negative effect of their mothers eating high levels of mercury containing fish.3

Dr. Gilbert Ross, medical director of the American Council on Science and Health stated – “Their exposure to fish with high mercury content has, so far, had no negative measurable effects……..”I would counsel the American public to not be afraid of eating fish, despite the allegations of advocate groups and some of our government agencies,” Ross advised. “These are merely hypothetical risks. In contrast, fish consumption has empirically proven to be very beneficial. Among other benefits, fish consumption helps combat heart disease, arrhythmias, and cognitive decline in old age.”

Dr. Philip Davidson, the lead researcher of the study stated, “The body of evidence so far indicates that there are no detectable effects in young children,” Scientists will continue to monitor the children to ensure negative effects do not manifest themselves later in life.”

At this point, a reader might ask why is mercury, a known toxin, not having a measurable negative effect on the development of these children?  Often times in medical research the mechanism of action of a compound or drug is not well known or understood, regardless of whether or not its effect is health promoting or health compromising.

In this case we have an ingredient, mercury (actually methyl mercury the form found in seafood) that is not exhibiting the negative effects on development that were anticipated to show up before these studies started.

Some unproven but plausible explanations are being suggested:

1-    It is well established in the medical literature that DHA (Docosahexanoic acid one of the omega-3 essential fatty acids found in fish) is important to normal neurological/brain development in young children.

It could be that the high levels of DHA consumed by eating fish multiple times per week, out strips any negative effects of mercury.

2-    It is proposed that almost all fish that are low in mercury, have a high selenium-to-mercury ratio and that is protective.  One theory explaining this is that mercury interferes with selenium related enzymes that are necessary for healthy neurological development.  When the amount of mercury exceeds the amount of selenium present, this healthy function of selenium is interrupted.

Another legitimate question would be – “What about the other toxins in seafood that have been reported to be dangerous? Specifically PCBs. (polychlorinated biphenyls) and dioxins.

Once again a paper was published talking about the high levels of PCBs found in farmed Salmon.  Once again the media jumped all over this and bloggers who are either not qualified to properly analyze the reporting of science based studies and statistics (or if they are qualified just didn’t do their homework) gave the fish eating public something else to be worried about.4

Well it turns out, that when the entire paper (not just the abstract) is read, the data showed that even though farmed salmon had a higher content of PCBs than wild salmon, its level was only about 2% of the level where governmental agencies thought it was of concern.  JUST 2%!!!  Meat and dairy levels are significantly higher!

So the accurate message to be derived from this study is that levels of PCBs in all the salmon tested were very low and that wild salmon was even lower than farmed salmon.  The take away is – Eat whatever source of salmon you can afford.  There are plenty of benefits from eating farmed salmon as well.

What about mercury from other sources besides fish?  Well a recent study done by the same Saychelle Island researchers tracked the impact of mercury amalgams (fillings) in pregnant woman on the develop of their children at birth and for the next five years. They found no negative effects in this study as well.4

Just to keep things in proper prospective, it is always possible that tracking kids from 5-15 years is not long enough for mercury related issues to crop up, but the benefits are very real and any future risks are currently at the very best just hypothetical.

Your call to action is – Eat around a pound and a half of low mercury seafood a week (refer to the list).  Both children and adults who do are likely to be substantially healthier and in my opinion, have a greater chance of living longer.

I wish you a long, vibrant, and happy life.

Curt Hendrix M.S. C.C.N.  C.N.S.
Chief Science Officer, Akeso Health Sciences LLC



(1)  Neurotoxicol Teratol. 1997 Nov-Dec;19(6):417-28.   Faroe island study

Cognitive deficit in 7-year-old children with prenatal exposure to methylmercury.
Grandjean P1, Weihe P, White RF, Debes F, Araki S, Yokoyama K, Murata K, Sørensen N, Dahl R, Jørgensen PJ.

1Institute of Community Health, Odense University, Denmark. p.grandjean@winsloew.ou.dk

(2)  Am J Epidemiol. 2016 Feb 1;183(3):169-82. doi: 10.1093/aje/kwv195. Epub 2016 Jan 5.  Barcelona study

Maternal Consumption of Seafood in Pregnancy and Child Neuropsychological Development: A Longitudinal Study Based on a Population With High Consumption Levels.
Julvez J, Méndez M, Fernandez-Barres S, Romaguera D, Vioque J, Llop S, Ibarluzea J, Guxens M, Avella-Garcia C, Tardón A, Riaño I, Andiarena A, Robinson O, Arija V, Esnaola M, Ballester F, Sunyer J.

(3)  JAMA. 1998 Aug 26;280(8):701-7. Seychelles Study

Effects of prenatal and postnatal methylmercury exposure from fish consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study.
Davidson PW1, Myers GJ, Cox C, Axtell C, Shamlaye C, Sloane-Reeves J, Cernichiari E, Needham L, Choi A, Wang Y, Berlin M, Clarkson TW.

1University of Rochester School of Medicine and Dentistry, NY 14642, USA. pdavidson@cc.urmc.rochester.edu

(4)  Neurotoxicol Teratol. 2013 Sep-Oct;39:57-62. doi: 10.1016/j.ntt.2013.07.003. Epub 2013 Jul 13.

Neurodevelopmental outcomes at 5 years in children exposed prenatally to maternal dental amalgam: the Seychelles Child Development Nutrition Study.
Watson GE1, van Wijngaarden E, Love TM, McSorley EM, Bonham MP, Mulhern MS, Yeates AJ, Davidson PW, Shamlaye CF, Strain JJ, Thurston SW,Harrington D, Zareba G, Wallace JM, Myers GJ.