• Start Here
  • About
  • Recommended
  • Books
  • Shop
  • My Account
  • Search
  • Recipes
  • Lifestyle
  • Autoimmunity
  • Nutrition
  • Gut Health
  • Wiki
  • Contact
  • Media Requests
  • Terms of Use
  • Privacy Policy
  • Affiliate
  • Refund Policy
  • Menu
  • Skip to left header navigation
  • Skip to right header navigation
  • Skip to primary navigation
  • Skip to secondary navigation
  • Skip to main content

The PaleoMom circular atom logo

The Paleo Mom is a scientist turned health educator and advocate.

  • Start Here
  • About
  • Recommended
  • Books
  • Shop
  • My Account
  • Search
  • Recipes
  • Lifestyle
  • Autoimmunity
  • Nutrition
  • Gut Health
  • Wiki
You are here: Home / Autoimmunity / The Mercury Content of Seafood: Should we worry?
mercury in seafood

The Mercury Content of Seafood: Should we worry?

August 11, 2012 //  by Dr. Sarah Ballantyne, PhD

Facebook0Tweet0Pin0LinkedIn0

About Dr. Sarah Ballantyne, PhD

Award-winning public speaker, New York Times bestselling author and world-renowned health expert, Dr. Sarah Ballantyne, PhD (aka The Paleo Mom) believes the key to reversing the current epidemics of chronic disease is scientific literacy. She creates educational resources to help people regain their health through diet and lifestyle choices informed by the most current evidenced-based scientific research.

We are often warned not to consume too much seafood over fears of the mercury contamination in these foods building up in our systems and leading to mercury poisoning.  Pregnant women are advised to limit seafood consumption to just two 6oz-servings per week over fears that mercury will cause brain damage to the developing fetus.  It certainly sounds scary, but is this concern well founded?

Mercury in Foods

Mercury is present in all foods.  Concentrations are quite low in fruits and vegetables because mercury uptake by plants from soil is low.  In contrast, mercury levels can be quite high in certain types of fish because fish absorb mercury from the water and from the organisms that they consume.  Methylmercury, an organic form of mercury, is the predominant form of mercury in fish.  It is concentrated in the muscle of the fish (not in the fat, which is why paying for low-mercury fish oil is quite pointless) and, because it binds so tightly to certain proteins in fish, it accumulates over time.  Fish at the lower end of the food chain tend to contain very low levels of methylmercury; but fish that eat other fish tend to have a higher concentration of methylmercury (this process is called biomagnification). 

*NEW* The Gut Health Cookbook!

The Gut Health Cookbook is fantastic! Thank you for researching and creating The Gut Health Cookbook! Such wonderful recipes! I’m so excited to try them all! -Sue

The Gut Health Cookbook puts the 20 Keys to Gut Health into practice with:

  • 180+ recipes featuring 61 gut health superfoods
  • Gut health food lists
  • Why’s behind each gut health superfood

Get instant digital access for $27.99

Buy Now

The concern over consumption of methylmercury is that, when ingested, it is almost completely absorbed from the gastrointestinal tract and distributed to all tissues (elemental or inorganic forms of mercury are not easily absorbed and some methylmercury is converted into elemental forms by your gut microflora).  Methylmercury also readily crosses both the blood-brain barrier and the placenta.  High levels of methylmercury are known to cause damage to the central and peripheral nervous system (the term “mad as a hatter” comes from felt makers in the 18th and 19thcenturies eventually going crazy due to chronic mercury exposure; mercury was used in felt production which was a common material in hats).  Yep, this definitely all sounds scary.

However, studies evaluating the effects of seafood consumption on the developing fetus have varied tremendously in their results.  On one end of the spectrum is brain damage (albeit subtle) from methylmercury exposure and on the other end of the spectrum is enhanced cognitive ability attributed to a maternal diet rich in omega-3 fatty acids (DHA, in particular).  So, should we eat more seafood or less?  The answer lies is in the selenium content of the seafood being eaten.

 

Selenium vs. Mercury

Selenium is a mineral that is required for activity of 25–30 different enzymes (selenoenzymes), whose job it is to protect the brain from oxidative damage.  Methylmercury irreversibly binds to selenium.  This is bad if you are exposed to methylmercury because it renders selenoenzymes inactive.  In fact, this is the mechanism through which methylmercury is believed to damage the brain and nervous system, by inhibiting the ability of selenoenzymes to protect these tissues from oxidants.  Very importantly, most typically consumed varieties of ocean fish contain much more selenium than methylmercury.  This is good for the fish (they don’t die from mercury exposure), but it is even better for us.  Selenium-bound methylmercury is not efficiently absorbed by our bodies.  What methylmercury is absorbed is already bound to selenium so it can’t interfere with our selenoenzymes.  The only fish that need to be avoided are those which contain more methylmercury than selenium (which is a fairly short list).

Fish that tend to contain very low levels of methylmercury include shellfish (for example oysters, clams, scallops, mussels), salmon, crab, shrimp, trout, herring, haddock, pollock (Boston bluefish), sole, flounder, lobster, Atlantic mackerel and lake whitefish.  However, any fish that has a higher selenium content than methylmercury contamination are perfectly safe to consume.  This includes the vast majority of ocean fish and approximately 97% of fresh water fish.  In fact, the only fish that you need to avoid are:  pilot whale, tarpin, swordfish, shark, marlin, king mackerel, and tilefish.  These recommendations are based on various small scale studies (see links below).  The EPA is currently undergoing a comprehensive survey of fresh and salt water fish and assigning what is called the Selenium-Health Benefit Value (Se-HBV) to each type of fish, which is essentially a ratio of selenium to methylmercury content of each fish.  

The Ultimate Support for Your AIP Journey!

Dr. Sarah Ballantyne has delivered an exceptional course and I highly recommend this to anyone looking to improve their health. There is something for everyone. It was extremely helpful and worth the investment. -Marie Schlichtig

The AIP Lecture Series is the ultimate Autoimmune Protocol educational experience! Learn directly from Dr. Sarah!

  • 6-week online course
  • 42 on-demand video lectures
  • dozens of printable guides
  • self-discovery exercises and action steps
  • online forum and guided discussions
  • support and guidance from Dr. Sarah Ballantyne!

The next session begins January 18th, 2021.
Register now to get bonus instant access to the Gut Health Fundamentals online course!

Learn More or ENROLL NOW

Increasing your dietary intake of selenium is one way to protect yourself from mercury exposure from food sources or from environmental factors (broken compact fluorescent light bulbs or amalgam fillings).  Selenium is found abundantly in seafood, seaweed, mushrooms, onions, Brazil nuts, sunflower seeds, and meat and poultry (especially the liver).  The vast majority of the fish that you are likely to find in a store or restaurant are perfectly safe to eat (swordfish being the obvious exception).  In fact, the dietary selenium that you will gain from including fish and shellfish in your diet (not to mention all the good DHA and EPA omega-3 fatty acids, iodine and very easily digested protein) will promote better health.  

 

Selenium-Health-Benefit Values

The selenium health benefit value (Se-HBV) is essentially a measure of the ratio of selenium to methylmercury in each fish. If the number is greater than zero, the fish has more selenium than mercury and is safe to consume. If
the number is less than zero, the fish contains higher levels of mercury than selenium and should be avoided.

Selenium in seafood protects against mercury so fish is safe to eat!

Scientists are just starting to understand the variability of the selenium health benefit value within a species of fish or shellfish and why some types of fish naturally have higher values than others (variability is due to the type of fish, size/age of the fish, geographic location and migration routes, and exact diet of the fish). Also note that selenium levels have not been measured in several species known to have high mercury, like tilefish and king mackerel. However, the take-home message is that most fish have positive selenium health benefit values, reflecting higher selenium than mercury levels, and are therefore safe to consume.

 

No Limits on Fish Consumption!

No, you don’t need to worry about the mercury content of (most) fish.  Actually, I recommend increasing your consumption of fish rather than decreasing, even for pregnant women!  Aiming for three 6oz servings of oily cold-water fish per week (on top of other varieties of fish and types of seafood) will provide you with your recommended intake of DHA and EPA.  And if you have unresolved inflammation, eating even more fish is a good idea.  Also, see Should We Be Worried About Radiation from Fukushima?

The Gut Health Guidebook!

The depth of information, practical tips, and the accessible way Dr. Sarah shows me how to apply complex science to improve my health is truly remarkable. -Wendy

The Gut Health Guidebook is the culmination of 6 years of research. This unprecedented deep dive into the gut microbiome delivers:

  • A new diet for gut health, built from the ground up
  • Essential gut microbiome superfoods
  • 20 Keys to gut health

Get instant digital access for $27.99

Buy Now

More information:

 Burger, J. and Gochfeld, M., Selenium and mercury molar ratios in commercial fish from New Jersey and Illinois: variation within species and relevance to risk communication. Food Chem Toxicol. 2013; 57: 235-45

Kaneko, J. J. and Ralston, N. V. Selenium and mercury in pelagic fish in the central north Pacific near Hawaii. Biol Trace Elem Res. 2007; 119(3): 242-54

Olmedo, P., et al., Determination of essential elements (copper, manganese, selenium and zinc) in fish and shellfish samples. Risk and nutritional assessment and mercury-selenium balance. Food Chem Toxicol. 2013; 62C: 299-307Ralston, NVC. “Selenium Health Benefit Values as Seafood Safety Criteria” EcoHealth 5, 442–455, 2008

Ralston, NVC et al. “Dietary and tissue selenium in relation to methylmercury toxicity” Neurotoxicology. 2008 Sep;29(5):802-11.

Western Pacific Regional Fishery Management Council http://wpcouncil.org/ 

Selenium and Mercury Ratio Graphic URL:  http://www.wpcouncil.org/councilmtgs/145th/Selenium_Poster_final.pdf

Energy & Environmental Research Center, University of North Dakota (EERC).” EERC Research Finds Mercury Levels in Freshwater and Ocean Fish Not as Harmful as Previously Thought”. June 22, 2009. Accessed at http://www.undeerc.org/news/newsitem.aspx?id=343

Health Canada,Bureau of Nutritional Sciences, Food Directorate, Health Products and Food Branch “Human Health Risk Assessment of Mercury in Fish and Health Benefits of Fish Consumption.” March 2007. Accessed at http://www.hc-sc.gc.ca/fn-an/pubs/mercur/merc_fish_poisson-eng.php

The Autoimmune Protocol E-Book!

One of my FAVORITE books I used to start the transition to AIP!!! It’s so helpful! I printed mine out and spiral bound it. Thank you for this! -Rita Davidson

The Autoimmune Protocol e-book is your up-to-date guide to jump-start your healing with the AIP today.

  • 3oo+ pages of quick-access information on the AIP
  • 4 weeks of meal plans with shopping lists
  • over 80 family-friendly recipes, all 100% AIP!

Get instant digital access for $19.99

Buy Now

http://chriskresser.com/is-eating-fish-safe-a-lot-safer-than-not-eating-fish#fn-672-1

http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.highlight/abstract/9503

Save

Save

Facebook0Tweet0Pin0LinkedIn0

Category: Autoimmunity, Nutrition

Get the Definitive AIP Resource

 

The Paleo Approach is the New York Times bestselling epic guidebook that explains all of the detailed WHYs behind every facet of the Paleo Autoimmune Protocol.

Get Your Copy HERE!

You may also like

  • Seafood Leek Soup-4
    Seafood Leek Soup

    I was craving cioppino right when I was giving up…

  • Seafood Leek Soup-4
    Seafood Leek Soup

    I was craving cioppino right when I was giving up…

  • Wine-Poached Salmon

    This is such a simple and quick way to prepare…

  • Lemon-Dill Poached Salmon Aerial View
    Lemon-Dill Poached Salmon

    Can you tell that I love salmon?  I do.  I…

  • Teriyaki-Inspired Poached Salmon

    My father-in-law was a very good cook.  One of his…

  • Seafood Leek Soup-4
    Seafood Leek Soup

    I was craving cioppino right when I was giving up…

  • Lemon-Tarragon Salmon

    My tarragon is going crazy in a pot in my…

  • Wine-Poached Salmon

    This is such a simple and quick way to prepare…

  • Lemon-Dill Poached Salmon Aerial View
    Lemon-Dill Poached Salmon

    Can you tell that I love salmon?  I do.  I…

  • Teriyaki-Inspired Poached Salmon

    My father-in-law was a very good cook.  One of his…

  • Seafood Leek Soup-4
    Seafood Leek Soup

    I was craving cioppino right when I was giving up…

  • Lemon-Tarragon Salmon

    My tarragon is going crazy in a pot in my…

Previous Post: «leg of lamb Greek-Inspired Slow-Roasted Leg of Lamb
Next Post: Basil-Avocado Baked Salmon Basil Avocado Baked Salmon-2 copy»
  • Contact
  • Media Requests
  • Terms of Use
  • Privacy Policy
  • Affiliate
  • Refund Policy

Lithium Apple logo

  • Facebook
  • Twitter
  • Pinterest
  • Instagram
  • YouTube
  • Itunes

Site Footer

Disclaimer: The majority of the links in ThepaleoMom.com posts and sidebar are affiliate program links.
This means that (most of the time) when you purchase a product linked from my site, I receive a commission.

Copyright © 2021 The Paleo Mom · All Rights Reserved · Powered by BizBudding Inc.