0

votes

How much fish can I eat?

Answered on August 19, 2014
Created August 19, 2012 at 3:43 PM

I'll soon be moving to Dibba, Oman where I'll live for the next seven months. I've lived there before so I know what foods are available. It's easy to buy Australian steak at the grocery store- but I'm sure its not grass fed. Chicken, lamb, eggs, and duck are always stocked in the grocery store. I'll take a bunch of organic coconut oil with me and I can buy lurpak butter there. I won't be able to find the brand of fish oil I take- so far the only brand that doesn't give me insomnia- and it's pricey so I don't really want to buy 7 bottles of it to take with me. There is a pretty awesome fish market in Dibba- where I can buy fresh whole fish and have it cleaned right there. My plan is to take my vacuum sealer which would enable me to buy a whole fish and eat it over the course of several weeks. This allows me to get the Omega 3 levels to balance the beef and chicken I'm eating. I'm pretty concerned about mercury levels in the fish- and I would also like to know which fish have the most omega 3 bang for the buck. Here are the types of fish I remember seeing or have bought before:

  • blackfin tuna
  • red snapper
  • Mackrel (not sure what kind)
  • baracuda
  • cuddlefish
  • sardines (which I don't particularly like)
  • cuddlefish (not really a fish...)
  • spiny lobster
  • a random assortment of jacks that I don't know the names of

    How often can I eat fish without overdoing it on the mercury? The Dibba fish market is one of my best options for getting meat so if I can I'll be eating lots of fish. Do different size fish of the same species contain different levels of mercury? For instance- is it better to buy several smaller tuna than one large tuna? I would assume that I would end up with the same amount of mercury either way.
  • Medium avatar

    (10611)

    on October 13, 2012
    at 06:53 PM

    Except that a major reason to eat the fish is to get protein, not fat. Is that a concern too? I eat wild fish all the time, farmed fish some of the time, and assume that amino acids are all the same.

    D41bd7b3d3b962eb0146f471eb632f56

    (2029)

    on October 13, 2012
    at 05:11 PM

    I'd at least consider the mercury a problem. I had a Spanish professor who was so invested in his health that he ate at least one can of tuna every day (I think it was more than that), and he ended up in the hospital with mercury poisoning. It does happen.

    782d92f4127823bdfb2ddfcbcf961d0e

    (5231)

    on October 13, 2012
    at 04:00 PM

    Selenium may not help. See this link: http://suppversity.blogspot.co.uk/2012/08/mercury-in-fish-not-harmless-regardless.html. I would stick with smaller (younger) fish, such as sardines, as they would not have absorbed as much mercury.

    C2cf95a5457c8ef5eb9ebb8cb1a5ec4d

    (20)

    on October 13, 2012
    at 03:41 PM

    Yes I agree - world oceans are becoming depleted of fish stocks and we have created a nightmare

    C2cf95a5457c8ef5eb9ebb8cb1a5ec4d

    (20)

    on October 13, 2012
    at 03:40 PM

    this is correct

    Medium avatar

    (2169)

    on August 20, 2012
    at 01:04 AM

    sweet thanks zach. I think this is what BonrBrothFast was trying to get at as well

    1e36119906da54831601a7c23674f581

    (698)

    on August 19, 2012
    at 10:26 PM

    Yeah i'm not sure why that happens.. it's a legit website. And no, mercury is not a concern in fish because of its binding affinity for selenium. Just search "mercury binding selenium" on pubmed and read up.

    D5d982a898721d3392c85f951d0bf0aa

    (2417)

    on August 19, 2012
    at 10:11 PM

    WARNING: I get a malware warning from my browser when I tried Zach's link. Regardless, I think I'll go precautionary principle on my fish.

    Medium avatar

    (2169)

    on August 19, 2012
    at 05:00 PM

    And also, the first link doesn't answer my question

    Medium avatar

    (2169)

    on August 19, 2012
    at 04:59 PM

    what tags did you use to find those? I did several searches and didn't run across them- I used "fish" and "fish oil" and "mercury"

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    5 Answers

    3
    1e36119906da54831601a7c23674f581

    (698)

    on August 19, 2012
    at 04:59 PM

    Basically mercury toxicity from fish is a pile of garbage..

    Mercury has a high binding affinity for selenium.. guess what else is present in quantity in almost every fish? Selenium.

    http://www.fishscam.com explains it all.. go ahead and eat your fish, fuck the FDA

    1e36119906da54831601a7c23674f581

    (698)

    on August 19, 2012
    at 10:26 PM

    Yeah i'm not sure why that happens.. it's a legit website. And no, mercury is not a concern in fish because of its binding affinity for selenium. Just search "mercury binding selenium" on pubmed and read up.

    Medium avatar

    (2169)

    on August 20, 2012
    at 01:04 AM

    sweet thanks zach. I think this is what BonrBrothFast was trying to get at as well

    D5d982a898721d3392c85f951d0bf0aa

    (2417)

    on August 19, 2012
    at 10:11 PM

    WARNING: I get a malware warning from my browser when I tried Zach's link. Regardless, I think I'll go precautionary principle on my fish.

    782d92f4127823bdfb2ddfcbcf961d0e

    (5231)

    on October 13, 2012
    at 04:00 PM

    Selenium may not help. See this link: http://suppversity.blogspot.co.uk/2012/08/mercury-in-fish-not-harmless-regardless.html. I would stick with smaller (younger) fish, such as sardines, as they would not have absorbed as much mercury.

    D41bd7b3d3b962eb0146f471eb632f56

    (2029)

    on October 13, 2012
    at 05:11 PM

    I'd at least consider the mercury a problem. I had a Spanish professor who was so invested in his health that he ate at least one can of tuna every day (I think it was more than that), and he ended up in the hospital with mercury poisoning. It does happen.

    2
    C2cf95a5457c8ef5eb9ebb8cb1a5ec4d

    on October 13, 2012
    at 03:38 PM

    My lab has studied the health-beneficial properties of omega-3 fatty acids in fish for about 35 years.

    All fish, on a global scale, are heavily contaminated by the toxin methyl-mercury.

    The US Food and Drug Administration (FDA) recommends no more than two (2) servings of fish per week to healthy adults.

    This is because, although the omega-3 fatty acids in fish are good for you, eating more than 2 servings of fish per week will increase your methyl-mercury intake and the toxicity of the methyl-mercury will override the benefits of the omega-3 fatty acids.

    Another interesting fact on the content of omega-3 fatty acids in fish:

    Today, most commercially available fish around the world are fish farmed. On fish-farms, fish are typically fed with corn pellets. Their normal food is omega-3 rich fatty acids from small marine organisms and plants from which the fish normally concentrate the omega-3 fatty acids.

    However, there is very little, if any, omega-3 fatty acid in corn pellets, and therfore very little omega-3 fatty acid in today's commercially available fish.

    We have thereby created a 'Frankenfish' - a fish that looks like a fish but has none of the health benefits.

    Enjoy!

    C2cf95a5457c8ef5eb9ebb8cb1a5ec4d

    (20)

    on October 13, 2012
    at 03:40 PM

    this is correct

    Medium avatar

    (10611)

    on October 13, 2012
    at 06:53 PM

    Except that a major reason to eat the fish is to get protein, not fat. Is that a concern too? I eat wild fish all the time, farmed fish some of the time, and assume that amino acids are all the same.

    C2cf95a5457c8ef5eb9ebb8cb1a5ec4d

    (20)

    on October 13, 2012
    at 03:41 PM

    Yes I agree - world oceans are becoming depleted of fish stocks and we have created a nightmare

    0
    Ba755fa2c130005537b9c15647da067d

    on June 26, 2014
    at 01:39 PM

    Personally, I am not convinced that the high levels of mercury in fish such as tuna and swordfish are safe if they exist in the presence of equimolar or higher concentrations of selenium.

    The definitive study on this issue is Chang’s, in which16 kittens were fed a diet of tuna containing 0.3 to 0.5 ppm mercury, plus supplementary nutrients and vitamins. After a period of seven months, two of the cats had mild ataxia and one had severe ataxia. The cats were sacrificed at 11 months and autopsy revealed extensive liver damage including damage to the mitochondria. In this case the selenium in the fish was not protective.

    In his review on Mercury: selenium interactions and health implications Dr Ralston, a supporter of the protective effect of selenium, says that “the 'protective effect' of selenium against mercury exposure may actually be backwards. Mercury’s propensity for selenium sequestration in the brain and endocrine tissues may inhibit formation of essential Se-dependent proteins (selenoproteins). Hence selenium’s 'protective effect' against mercury toxicity may simply reflect the importance of maintaining sufficient free selenium to support normal selenium-dependent enzyme synthesis and activity.” But even that may not be enough to completely nullify mercury’s toxic effects.

    In the same review he mentions the study by Friedman into the protective effects of dried swordfish on methylmercury toxicity in rats. He states that rats fed a diet of swordfish and methylmercury showed no signs of neurotoxic effects, while rats fed a control diet spiked with methylmercury without swordfish did. Dr Ralston attributes this to the protective effects of selenium. However, the protective effect is not that impressive.

    In spite of the proposed protective effect of selenium, both the control group and the experimental groups died, at 4.6 and 5.3 weeks respectively. If the rats had lived longer, there would have been more chance for any neurological effects to manifest. It should also be noted that the control diet included 15% casein which has been shown to reduce mercury excretion in rats, and thus may have exacerbated the effects of mercury toxicity in the control rats.

    These studies do not take into account the long-term effects of mercury exposure. The lower the dose of mercury, the greater the delay in the manifestation of symptoms. Deborah Rice fed monkeys a diet of 50 micrograms of methylmercury for 7 years. After cessation, blood levels quickly dropped to normal levels. When the monkeys were tested at 13 years of age they displayed clumsiness and loss of fine motor skills as well as decreased sensitivity to touch. Humans are exposed to mercury for decades and have longer to develop overt signs of mercury toxicity.

    One of the problems with the studies from the Seychelles and the Faroe Islands on the effect of methylmercury on neurodevelopment is that they rely on hair testing of mercury levels. This is often accurate, but does not take into account the fact that mercury disrupts cellular transport due to its affinity for sulfhydryl molecules. These molecules often form the active site in cellular transport proteins. Mercury binds to these active sites, altering mineral transport. This can result in hair readings for mercury and other toxic elements that are artificially low. Thus children with high exposure may actually be classed as having low exposure. Hair analysis actually provides a measure of how much mercury is being excreted. The most important factor is how much mercury is being retained in the body and that is difficult to measure.

    Amy Holmes found that autistic children, even though they had higher exposures to mercury through their mothers’ dental amalgams and Rhogam injections, had lower levels of mercury in their hair, implying a reduced ability to excrete mercury. The following hair test illustrates the ability of mercury to disrupt mineral transport - http://www.livingnetwork.co.za/files/hairtest_564.pdf

    This is clearly an abnormal distribution of elements (all except one of the essential elements are below the 50th percentile) associated with a low reading for mercury.

    It may be safe for some individuals with optimal antioxidant and metallothionein status to consume tuna and other high mercury fish, but I think for many it would be safer to stick to fish such as sardines and salmon, which also have high levels of omega 3s, but much lower levels of mercury.

    David Hammond

    author – Mercury Poisoning: The Undiagnosed Epidemic.

    References

    Chang, L. W., & Yamaguchi, S. (1974). Ultrastructural changes in the liver after long-term diet of mercury-contaminated tuna. Environmental Research, 7(2), 133-148.

    Raymond, L. J., & Ralston, N. V. (2004). Mercury: selenium interactions and health implications. Seychelles Medical and Dental Journal, 7(1), 72-77.

    Rowland, I. R., Robinson, R. D., & Doherty, R. A. (1984). Effects of diet on mercury metabolism and excretion in mice given methylmercury: role of gut flora. Archives of Environmental Health: An International Journal, 39(6), 401-408.

    Rice DC. Delayed neurotoxicity in monkeys exposed developmentally to methylmercury. Neurotoxicology. 1989 Winter; 10(4):6450-50.

    Holmes, A. S., Blaxill, M. F., & Haley, B. E. (2003). Reduced levels of mercury in first baby haircuts of autistic children. International journal of toxicology , 22 (4), 277-285.

    0
    Ba755fa2c130005537b9c15647da067d

    on June 26, 2014
    at 01:38 PM

    Personally, I am not convinced that the high levels of mercury in fish such as tuna and swordfish are safe if they exist in the presence of equimolar or higher concentrations of selenium.

    The definitive study on this issue is Chang’s, in which16 kittens were fed a diet of tuna containing 0.3 to 0.5 ppm mercury, plus supplementary nutrients and vitamins. After a period of seven months, two of the cats had mild ataxia and one had severe ataxia. The cats were sacrificed at 11 months and autopsy revealed extensive liver damage including damage to the mitochondria. In this case the selenium in the fish was not protective.

    In his review on Mercury: selenium interactions and health implications Dr Ralston, a supporter of the protective effect of selenium, says that “the 'protective effect' of selenium against mercury exposure may actually be backwards. Mercury’s propensity for selenium sequestration in the brain and endocrine tissues may inhibit formation of essential Se-dependent proteins (selenoproteins). Hence selenium’s 'protective effect' against mercury toxicity may simply reflect the importance of maintaining sufficient free selenium to support normal selenium-dependent enzyme synthesis and activity.” But even that may not be enough to completely nullify mercury’s toxic effects.

    In the same review he mentions the study by Friedman into the protective effects of dried swordfish on methylmercury toxicity in rats. He states that rats fed a diet of swordfish and methylmercury showed no signs of neurotoxic effects, while rats fed a control diet spiked with methylmercury without swordfish did. Dr Ralston attributes this to the protective effects of selenium. However, the protective effect is not that impressive.

    In spite of the proposed protective effect of selenium, both the control group and the experimental groups died, at 4.6 and 5.3 weeks respectively. If the rats had lived longer, there would have been more chance for any neurological effects to manifest. It should also be noted that the control diet included 15% casein which has been shown to reduce mercury excretion in rats, and thus may have exacerbated the effects of mercury toxicity in the control rats.

    These studies do not take into account the long-term effects of mercury exposure. The lower the dose of mercury, the greater the delay in the manifestation of symptoms. Deborah Rice fed monkeys a diet of 50 micrograms of methylmercury for 7 years. After cessation, blood levels quickly dropped to normal levels. When the monkeys were tested at 13 years of age they displayed clumsiness and loss of fine motor skills as well as decreased sensitivity to touch. Humans are exposed to mercury for decades and have longer to develop overt signs of mercury toxicity.

    One of the problems with the studies from the Seychelles and the Faroe Islands on the effect of methylmercury on neurodevelopment is that they rely on hair testing of mercury levels. This is often accurate, but does not take into account the fact that mercury disrupts cellular transport due to its affinity for sulfhydryl molecules. These molecules often form the active site in cellular transport proteins. Mercury binds to these active sites, altering mineral transport. This can result in hair readings for mercury and other toxic elements that are artificially low. Thus children with high exposure may actually be classed as having low exposure. Hair analysis actually provides a measure of how much mercury is being excreted. The most important factor is how much mercury is being retained in the body and that is difficult to measure.

    Amy Holmes found that autistic children, even though they had higher exposures to mercury through their mothers’ dental amalgams and Rhogam injections, had lower levels of mercury in their hair, implying a reduced ability to excrete mercury. The following hair test illustrates the ability of mercury to disrupt mineral transport - http://www.livingnetwork.co.za/files/hairtest_564.pdf

    This is clearly an abnormal distribution of elements (all except one of the essential elements are below the 50th percentile) associated with a low reading for mercury.

    It may be safe for some individuals with optimal antioxidant and metallothionein status to consume tuna and other high mercury fish, but I think for many it would be safer to stick to fish such as sardines and salmon, which also have high levels of omega 3s, but much lower levels of mercury.

    David Hammond

    author – Mercury Poisoning: The Undiagnosed Epidemic.

    References

    Chang, L. W., & Yamaguchi, S. (1974). Ultrastructural changes in the liver after long-term diet of mercury-contaminated tuna. Environmental Research, 7(2), 133-148.

    Raymond, L. J., & Ralston, N. V. (2004). Mercury: selenium interactions and health implications. Seychelles Medical and Dental Journal, 7(1), 72-77.

    Rowland, I. R., Robinson, R. D., & Doherty, R. A. (1984). Effects of diet on mercury metabolism and excretion in mice given methylmercury: role of gut flora. Archives of Environmental Health: An International Journal, 39(6), 401-408.

    Rice DC. Delayed neurotoxicity in monkeys exposed developmentally to methylmercury. Neurotoxicology. 1989 Winter; 10(4):6450-50.

    Holmes, A. S., Blaxill, M. F., & Haley, B. E. (2003). Reduced levels of mercury in first baby haircuts of autistic children. International journal of toxicology , 22 (4), 277-285.

    Medium avatar

    (2169)

    on August 19, 2012
    at 04:59 PM

    what tags did you use to find those? I did several searches and didn't run across them- I used "fish" and "fish oil" and "mercury"

    Medium avatar

    (2169)

    on August 19, 2012
    at 05:00 PM

    And also, the first link doesn't answer my question

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