What Is The Deal with Fish, Omega 3’s and Mercury?

By now, everyone who reads about food and health should know that seafood, particularly fatty fish such as king mackerel, salmon and tuna, are good for you. They are full of beneficial fats, particularly omega 3 fatty acids, which protect against heart disease, diabetes and help children and developing fetuses build better brains and eyes.

On top of that, those fish are mighty tasty, and can add an awful lot of flavor to a healthy diet.

That’s all kinds of great, isn’t it?

Well, yeah, sort of.

It -would- be all kinds of great if it wasn’t for the fact that thanks to coal burning power plants and pollution from heavy industry, our oceans and waterways are all contaminated with a compound called methyl mercury. Methyl mercury makes its way into the food chain, and eventually into us insidiously by being consumed by small critters such as filter feeders or plankton, which in turn get eaten by consecutively larger fish, until those big, tasty fatty fish full of their wonderful omega 3’s get caught and eaten by us, humans, the critters at the top of the food chain.

The thing is, the methyl mercury doesn’t just travel up the food chain, it is bioaccumulative. This means that t gets stored in body tissues of the organisms that eat it, the concentration of contamination rising the higher it travels up the food chain until it stops with humans. It is fat soluble, and in humans, is stored in body fat.

Except humans aren’t really at the top of the food chain. Specific humans are the end-point of the food chain–fetuses and breast-fed babies are actually at the very top of the food chain. And, guess what–these wee humans who teeter at the top of the food chain are also the most vulnerable to the effects of methyl mercury. The bodies of nursing women often use the mother’s accumulated body fat, which can have mercury stored up in it for years, in order to make milk, meaning that mercury-contaminated fish that was eaten years before can essentially contaminate the milk she is feeding her baby.

Want to know the effects of mercury poisoning? Read a bit about what happened in Minimata, Japan, back in the 1950’s when people unkowingly ate fish from Minimata Bay which had been contaminated by a local fertilizer factory. Brain damage, neurological dysfunction, blindness, muscular and skeletal abnormalities have all been linked to severe cases of mercury poisoning.

Of course, you notice I said “severe mercury poisoning.” As most saavy readers probably know the levels of mercury in the fish eaten by the victims in Minimata was much higher than the levels the EPA is reporting in fish in the US marketplace.

However, even lower levels of mercury are problematic, especially for fetuses, babies and small children.

Which is why the US government has warned pregnant and nursing women and young children against eating canned tuna, king mackerel, shark, and grouper, and to limit their consumption of many other kinds of seafood, including fresh and canned tuna.

But, of course, that would limit women and children’s access to the health benefits of the omega 3’s in fish. (Now is a good time to note that one can get omega 3’s from flaxseed, flaxseed oil, purified fish oil supplements that have had the mercury removed from them, grassfed beef, eggs, and dairy. Fish derived omega 3’s are being used to supplement all sorts of processed foods in order to provide risk-free health benefits.)

In light of this ironic problem that large fatty predatory fish contain lots of what is good for humans as well as lots of what will cause humans harm, a great many Americans have avoided fish altogether, because the risk of mercury poisoning outweighed the health benefits in the minds of many consumers.

However, a pair of new studies on the subject show that the potential benefits of eating fish outweigh the potential risks of mercury contamination. All reports of the studies however, are careful to reiterate the US government’s guidelines to women of childbearing age, pregnant or nursing women, and young children: eat only certain types of fish in specifically prescribed “safe” amounts. (For EPA information about various species of fish and the levels of mercury contamination found in them, look here.)

However, various consumer and public interest groups contend that the government’s guidelines do not go far enough to protect the public, particularly children, from the dangers of mercury contamination in seafood.The Public Interest Research Group states int their 2001 report, Brain Food: What Women Should Know About Mercury Contamination In Fish, “If American women ate a varied diet of FDA’s recommended 12 ounces of fish a week (and none of the four prohibited fish) they would expose more than one fourth of all fetuses (one million babies) to a potentially harmful dose of methylmercury for at least one month during pregnancy.”

The Center for Science in the Public Interest criticized (and rightfully so, in my opinion) the recent reports for not really providing useful tools for consumers to safely eat fish. In addition, the CSPI points out something that most major media coverage has ignored about one of the reports, titled, Seafood Choices: Balancing the Benefits and the Risks, which was commissioned by the National Marine Fisheries Service, a governmental body “dedicated to the stewardship of living marine resources through science-based conservation and management, and the promotion of healthy ecosystems.”

Interestingly, these reports are being trumpeted in most media outlets as being “independent,” and thus not connected with the fishing industry. However, one branch of the National Marine Fisheries Service, the
NOAA Fisheries Office of Constituent Services, is involved in “promoting and facilitating trade for the U.S. seafood and aquaculture industries by expanding existing markets and opening new ones for U.S. producers and processors”.

(Hrm…suddenly this report is not sounding as independent and unbiased as most media outlets portray it as being. In fact, I am sensing a bit of conflict of interest here.)

According to CSPI, this report downplays the dangers of consuming mercury-contaminated species for children, and does not follow the FDA’s recommendations that children eat smaller portion sizes. This action does not take into account the difference in body weight between children and adults and ignores the fact that what is a non-toxic amount of mercury to an adult is proportionally quite dangerous when it comes to a child.

In July, prior to the release of these reports, Consumer Reports took to task the government’s assertion that canned light tuna was lower in mercury (and thus safe for pregnant and nursing women and young children to consume) than albacore tuna, when they did an independant analysis of FDA data on the subject. They concluded that pregnant women should simply avoid eating canned tuna altogether, rather than follow the EPA guidelines.

So, what is my take on all of this?

Well, I am of the opinion that pregnant and nursing women, and infants and children are probably better off getting their omega 3 fatty acids from non-fish sources at this time. The evidence is not as clear cut as the new media stories want to portray it, and I, personally see no reason for pregnant and nursing women who have no idea how much mercury they have already accumulated in their body fat to risk adding to that already present store of a toxic material by ingesting more of it. The potential risk to the developing bodies and brains of our infants is just too great, and there are other ways to get those omega 3’s than just by eating fish. Flax seeds, eggs, dairy and meat from grass-fed livestock and purified fish-oil based supplements are all good, safe sources of omega 3’s in the human diet.

That said, I have to admit that I still miss my tuna and salmon, and have recently indulged in some wild-caught smoked salmon, which most sources cite as being minimally contaminated with mercury.

However, not knowing how much mercury I have stored away in my body fat which is slowly melting away as it is being metabolized into breast milk production, I am not about to go hog-wild and start eating salmon every day, not matter what any governmental agency or scientist paid by any said agency tells me is safe.

For some reason, I just don’t quite trust them enough to take their advice on this matter, and put at risk my daughter’s developing brain.

8 Comments

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1. Interesting post. I am conflicted about my fish consumption. One the one hand, I’m supposed to be on an anti-inflammatory diet because of my chronic pain, which tends to mean consuming a lot of fish. On the other hand, with all the health problems I have do I really want more chemical exposure? My compromise has been eating sushi (raw tuna) a few times a month and wild-caught salmon about once a week and, and the rest of the time avoiding fish but taking a fish oil supplement.

   It’s hard to weigh pros and cons when so much of the info is so biased and when we honestly don’t know the full extent of mercury’s effects on the human body. But I think I’d probably tend towards your position if I was pregnant or nursing.

   Comment by Gluten-Free By The Bay — October 19, 2006 #

2. Thank you for this article. A doctor recently encouraged me to eat more fish, which I rarely do despite loving it. I’m going to comply with his advice simply because it’s one of my favorite foods. It’s good to know the downside as well, no matter what my choice is.

   Everything in moderation, right?

   Comment by Susan — October 19, 2006 #

3. Thanks for the good information, Barbara. When I went to my first prenatal visit, the doctor gave me a sample of an Omega-3 supplement, and the company selling it is clearly using the fish scare as a marketing tool. Do you think the need for Omega-3 for a pregnant woman is so great that a supplement is necessary (in addition to the prenatal vitamins and folic acid I’m already taking)? Or, can I get what I need from non-fish food, like eggs and grain-fed beef (although beef doesn’t really appeal to me at the moment)?

   Since I found out I was pregnant, I’ve been scouring your pre-Kat posts; so many good things to think about, thanks.

   Comment by Jennifer — October 20, 2006 #

4. Barbara, did you see this story on the BBC site?

   http://news.bbc.co.uk/2/hi/health/6057732.stm

   The story is based on a JAMA report on the benefits of eating oily fish. They claim that at worst the mercury reduces the benefit of the omega-3s (which doesn’t actually make sense – we all know that mercury is in general a Very Bad Thing to consume).

   Personally, I’m a bit sceptical of the whole omega-3 bandwagon. I don’t think we can blame the stupidity of our politicians on a lack of omega-3 or assume that our kids will be wonder-children if they have it. So I eat these fish rarely, but mainly because I’m against fish-farming and here in Europe it is next to impossible to find tuna or salmon that isn’t farmed! (And when I do find it, it’s what the French call hors de prix or “beyond expensive”!)

   Comment by Meg — October 23, 2006 #

5. […] What Is The Deal with Fish, Omega 3’s and Mercury?  […]

   Pingback by Women: Eat more seafood while pregnant, have smarter kids at Fresh. Healthy. Useful. — March 4, 2007 #

6. Wild-caught salmon generally contain a “safe” amount of mercury. Watch out for farmed.

   Comment by Masked — April 4, 2007 #

7. Thanks for doing the research on this. I guess we all realise that ‘as close to nature as possible’ is always going to best for us, presuming, of course, that the environment of that ‘nature’ is uncontaminated. Fortunately I live at the bottom of the world (next stop – Antarctica) where the fish will be reasonably safe to consume. I guess everything is a trade-off: We want (and need)the nutritional benefits, which may be lessened, though not necessarily outweighed, by some contamination drawback. ‘Who to believe’ is a very real concern, because anyone who has done research will know that there is so much conflicting advice out there, that the well-intentioned become very confused. I tend to stick to basics: let’s say we’re all agreed that a variety of fresh, raw fruits and vegetables go a long way to keep us healthy (they have been proven to strengthen the immune system and repair DNA damage) Okay. So that’s better than canned, cooked, dried, etc. Now, to get organically grown produce would be one step better, agreed? And to get the produce picked ripe for maximum nutrition, not under-ripe in consideration of maximum shelf life would be another gain, wouldn’t it? So, I guess we would all concede that to grow your own is ideal, but presents it’s own problems: what busy mother has the time? Or garden space? Or climate? Etc. But at least we can head TOWARDS that ideal, even if it is only to start sprouting alfalfa in jars on our kitchen windowsill. A very good ‘second best’ to this would have to be a product called Juice Plus. It is basically 17 different fruits and vegies, picked ripe, tested for pesticides, etc, juiced and dehydrated into powder at low temperature to preserve the nutrients. Being a wholefood source it contains thousands of types of vitamins, minerals, enzymes, antioxidants, etc, and not just a handful of elements processed into a multivitamin tablet which may not be easily assimilated by the body. If you are concerned about your family’s foundational health, and are not able to grow much of your own, this is definitely worth a look. Pretty economical too.
   Yes, the plant-sourced Omega 3s / 6s are available as you say, such as in flaxseed, but the concentration of it is much lower, so you’d have to eat an awful lot to benefit! It is possible (but not simple) to raise your own fish in the backyard with aquaculture methods, but I guess that would be for the enthusiast.

   Comment by Sue from Tasmania — July 5, 2007 #

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