Friday Favorites: Avoiding Fish for Five Years Before Pregnancy

The problem with fish advisories that tell pregnant women to cut down on fish consumption is that it may be too late for certain persistent pollutants.

In my other video on this topic, How Long to Detox from Fish Before Pregnancy ( ), I mentioned a study that suggests detoxing from fish for one year to see mercury levels decrease, but other pollutants take longer to leave our system.

For optimum brain development, consider a pollutant-free source of omega-3 fatty acids. See Should Vegan Women Supplement with DHA during Pregnancy? ( ).

There are other reasons you may want to avoid excessive amounts of any animal protein. See The Effect of Animal Protein on Stress Hormones, Testosterone, and Pregnancy ( ).

What about A Plant-Based Pregnancy? ( ) Check out the podcast.

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Thanks for watching. I hope you’ll join in the evidence-based nutrition revolution!
-Michael Greger, MD FACLM

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Dave McKinnon

  • @user-vi6ro8bd4l says:

    Oh My Poseidon! This is so depressing. I eat sardines almost weekly and take fish oil for Omega3 (DHA/EPA) daily.

    • @Spock_Rogers says:

      Fish suffer.

    • @nuovoaccount998 says:

      It is indeed, i’ll add these substances to my blood checkup

    • @sundiataq says:

      Sardines are very low in Mercury… Smaller fish, lower on the food chain generally speaking have substantially lower mercury levels than larger fish like tuna.

    • @Spock_Rogers says:

      Joe Rogan got arsenic poisoning from sardines.

    • @sundiataq says:

      @@Spock_Rogers with all due respect, Joe Rogan isn’t the brightest bulb in the room. He was eating 3 cans of sardines a day. There is such a thing as a “balanced diet”, and 3 cans of sardines a day isn’t it. There is arsenic in many things we consume. Even the water we drink can contain arsenic. But it’s the dose that makes the poison.

  • @Apollo440 says:

    Big questions:
    Do these studies only include fish from the ocean / SEAfood or lake and stream caught fish as well?
    The data on crayfish (“lobster of the lake”) contamination 03:20 seems to be very, very low, which could indicate that we can eat the far less popular and not that readily available, yet indefinitely fresher lake / river fish…

    • @xperience-evolution says:

      Much of the poison and garbage in oceans come from rivers. Better leave the fish alone.

    • @Apollo440 says:

      @@xperience-evolution It’s like they say “if you want to save the fish – then stop eating them”

    • @Apollo440 says:

      @@xperience-evolution but on a more serious note – tankers and ocean liners usually go throgh the big seas and oceans. And, although it would be optimistic to think that the river / lake fish you can buy is cleaner – it is also a factor to consider. As well as the factor of factories and cities dumping stuff into the water, whether there’s a fishing farm further down the stream or not. TL:DR – Dr. G, in this video, showed a statistic about crawfish, which are way cleaner than their relatives from the ocean.

  • @Kayte... says:

    Is the mislabeling actually on the kind of fish or whether or not it’s wild caught. I know fish kinds are mislabeled. Anyway your concluding statement may be misleading unless farmed versus wild caught is also mislabeled. Which wouldn’t surprise me. Same as uncaged/free range chickens who still only have the spot they’re standing in available. They are still unable to walk freely as cage free implies.

    • @nuovoaccount998 says:

      It doesn’t really matter since from the studies you could clearly see that no matter where you buy fish, you’re doomed.

  • @jessicaroseburrowes says:

    The Kosher food laws, which require fish to have both fins and scales to be considered permissible for consumption, do not directly address the issues of mercury and ammonia levels in fish. However, these dietary laws may inadvertently align with some modern dietary guidelines that advise against consuming certain types of fish known to have higher levels of mercury and other contaminants. Fish without scales, such as sharks and swordfish, tend to be higher on the food chain and can accumulate more mercury in their tissues¹. Therefore, while the Kosher laws are not based on modern scientific understanding of contaminants, they may offer some protection against them.

    Regarding the advice for pregnant women to avoid fish for five years before pregnancy, it’s important to consider the potential nutritional losses, particularly omega-3 fatty acids, which are crucial for fetal brain development. Fish is a primary source of two important omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). While nuts, seeds, and legumes can provide alpha-linolenic acid (ALA), a precursor to EPA and DHA, the conversion rate of ALA to EPA and DHA in the human body is low¹⁶. This means that completely avoiding fish could lead to inadequate intake of EPA and DHA.

    The minerals in plant-based sources like nuts, seeds, and legumes are indeed bioavailable, but they may not always be as readily absorbed as those from animal sources due to the presence of antinutritional factors like phytates¹⁵. Fermentation can enhance the bioavailability of these nutrients by reducing antinutritional factors⁵⁶. However, fermentation does not produce EPA and DHA; thus, it cannot fully replace the nutritional benefits of fish. For individuals who choose not to consume fish, algae-based supplements can be a direct source of EPA and DHA¹⁶.

    In summary, while fermentation can improve the nutrient profile of plant-based foods, it cannot fully substitute the unique nutrients found in fish. Pregnant women or those planning pregnancy should consult healthcare providers to balance the benefits of consuming fish with the risks of exposure to contaminants, and to explore alternative sources of essential nutrients if necessary.

    (1) All About Kosher Fish – Parshat Shemini –
    (2) The 7 Best Plant Sources of Omega-3 Fatty Acids – Healthline.
    (3) Vegetarian diet: How to get the best nutrition – Mayo Clinic.
    (4) A review of fish meal replacement with fermented wastes in aquaculture.
    (5) Fermentation in aquafeed processing: Achieving sustainability in feeds ….
    (6) Kosher Fish List –
    (7) Kosher Seafood: Exploring the Dietary Laws and Delicious Options.
    (8) Kosher Fish for the Kosher Consumer – Chicago Rabbinical Council.
    (9) (PDF) A review of fish meal replacement with fermented biodegradable ….
    (10) Avoiding Fish for 5 Years Before Pregnancy.
    (11) Avoiding Fish for 5 Years Before Pregnancy.
    (12) Eating Fish During Pregnancy – Safe or Unsafe?.
    (13) Friday Favorites: Avoiding Fish for Five Years Before Pregnancy.
    (14) Pregnancy and fish: What’s safe to eat? – Mayo Clinic.
    (15) Is it safe to eat seafood and fish during pregnancy? | BabyCenter.
    (16) Eating Fish During Pregnancy: Safe Fish for Pregnant Women & Fish to Avoid.
    (17) If you’re worried about inflammation, stop stressing about seed oils ….
    (18) Which Nut is The Healthiest? Omega-3 Ratios in Nuts and Seeds.
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  • @adrian_zombturtle148 says:

    Ok who’s the one putting mercury in the fish ? You better stop it!

    • @quartqwertbudisgood says:

      Unfortunately mercury is very useful and common in many industrial processes 🙁 including some food production

    • @phillippinter7518 says:

      It’s in the ocean, a lot of pollutants run into the ocean.

  • @kathy.7475 says:

    Tuna was the only fish we could afford after we got married. Course that was over fifty years ago that our first was born. I wonder how much, if any, mercury was in fish then?

    • @quartqwertbudisgood says:

      Probably less, mercury is still very useful and common and now more poor countries are using it in industrial processes

  • @jessicaroseburrowes says:

    The relationship between mercury levels and ammonia in fish is complex and involves understanding the bioaccumulation of mercury, the production and excretion of ammonia, and the factors that influence these processes.

    • Mercury in Fish:
    Mercury, particularly in the form of methylmercury (MeHg), is a toxin that can accumulate in fish tissues, especially in fatty areas. The bioavailability of mercury in fish can vary and is influenced by several factors, including the mercury source, cooking methods, and the presence of other nutrients⁵. Mercury’s bioavailability is not always 100%; it can be less, which means not all ingested mercury is absorbed into systemic circulation⁵.

    • Ammonia in Fish:
    Fish produce ammonia as a waste product, primarily through the metabolism of proteins and amino acids. Ammonia is toxic to fish and is usually excreted through the gills. However, some fish species can accumulate high levels of ammonia in their brain or defend against ammonia toxicity by enhancing the effectiveness of ammonia excretion through active transport, manipulation of ambient pH, or reduction in ammonia permeability through the branchial and cutaneous epithelia¹.

    • Calculating Risk:
    To calculate the risk of mercury and ammonia in fish accurately, one must consider the bioavailability of these substances and their storage in fatty tissues. For mercury, risk assessors often assume a bioavailability of 95%–100% in their models, but this may not be accurate. Studies have shown that the overall absorption estimates for mercury can range from 12% to 79% for MeHg and 49% to 69% for Hg (II), consistently less than 100%⁵.

    For ammonia, the risk calculation would involve understanding the rate of production and the effectiveness of excretion mechanisms. Factors such as the species of fish, environmental conditions (e.g., water temperature, pH, salinity), and the fish’s diet can affect ammonia production and excretion².

    • Bioavailability and Toxin Storage:
    Bioavailability refers to the extent and rate at which a substance, like mercury or ammonia, enters systemic circulation, becoming available at the site of physiological activity. Toxin storage, particularly for mercury, occurs in fatty tissues where it can accumulate over time. The exocrine excretion of these substances involves their removal from the body, which, for ammonia, is primarily through the gills, and for mercury, can involve complex detoxification processes.

    • Exocrine Excretion:
    Exocrine excretion refers to the process by which waste products are eliminated from the body. In fish, ammonia is excreted through the gills, while mercury does not have a straightforward excretion pathway and can remain in the tissues for a longer duration.

    To accurately assess the risk of mercury and ammonia in fish, it is essential to have detailed knowledge of the specific fish species, their environment, and their diet. Additionally, understanding the bioaccumulation process, which includes both aqueous and dietary uptake, is crucial⁶. This information can then be used to develop models that estimate the risk based on the bioavailability and storage of these toxins in fish tissues.

    (1) A Review of Mercury Bioavailability in Humans and Fish – MDPI.
    (2) Ammonia production, excretion, toxicity, and defense in fish: a review.
    (3) A broader look at ammonia production, excretion, and transport in fish ….
    (4) Bioaccumulation of contaminants in fish | SpringerLink.
    (5) Ammonia Control in Aquaculture: Keep Levels Low & Fish Healthy.
    (6) The Expert Guide to Reducing Ammonia in Your Aquarium.
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  • @mchagawa1615 says:

    Thank you <3 glad I've not eaten fishes for many years by now 🙂 flaxseeds (and chia, and green leafy vegetables) are where I get my omega 3s 🙂

  • @Allmighty_Vidar says:


  • @lorenadavila3161 says:

    Thank you for these videos . Can we get some on Lymphatic system. Lymphedema.? Tysm❤

  • @roligue says:

    I’m convinced…no more fish for me

  • @economicdevelopmentplannin8715 says:

    Healthiest birthing ages are around 21 to 22, per a Search 🔎 for maternal age and fetal loss.

    So girls shouldn’t eat any seafood starting at age 16 ❤

  • @hayrola2 says:

    Damn, this hit hard

  • @androz38 says:


  • @syrahsmythe says:

    “Avoiding fish for 5 years before pregnancy” – haha, more like avoiding fish forever!!

    • @StanDupp6371 says:

      That is not what Dr. Shigeaki Hinohara said. Dr. George Mann who lived to age 95 said to consume fish 3 times per week and Dr. Hinohara would say the same.

  • @VeganLinked says:

    Thanks so much for doing this! This is going to be great to share on my new website called raising children vegan. I just built this recently to compliment the interviews I am producing moving forward focused on this topic for dominantly if not exclusively. 💚

  • @trevorregay9283 says:

    man…….trying to find Atlantic or Pacific salmon wild caught is not easy………plenty of sockeye salmon wild caught though…….so curiously, wondering if there is a good source of farm salmon that is not as bad as wherever it is they got these statistics from ……so going there are some farmed fish facilities that manage to keep the mecury and pollutitue levels down……..

  • @deconcoder says:

    The video and none of the comments mention that mercury is concentrated higher in the food chain. Also, really good products are tested. Hello?

  • @3cardmonty602 says:

    Don’t listen to this guy. He publishes faulty data.

  • @AndrewPawley11 says:

    I love this channel!

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