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Tuna/Swordfish/Shark... Mercury Levels

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CHTHONIC
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2004/02/28 13:03:34 (permalink)
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Tuna/Swordfish/Shark... Mercury Levels

I've read many an article on mercury levels on the larger sea-dwelling fish. Some say that tinned tuna is fine for you because only young tuna are used for canning and thus their fatty tissues haven't had time to take in dangerously high mercury levels. Others (mostly Canadian/American-based) say that canned Tuna still has excessive mercury deposits in its fatty tissues.

Swordfish and Shark undoubtedly have very high levels of mercury in their fatty tissues and should only be consumed once a month. No-one disputes this fact.

If any of you have any decent articles on canned tuna as regards to mercury content, i'd be interested to read them,

Thanks Alex.
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    ArchAngel
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 18:23:34 (permalink)
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    This is something I'd definitely like to know. I consume lots and lots of canned tuna! Hopefully I wont regret it in years to come!
    #2
    levi
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 18:30:01 (permalink)
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    canned tuna is fin as it is precooked before canning so the oil has been removed, so no good for essential fats either, fresh or frozen still has oil in.

    i have done a survey of locally caught fish(no swordfish or shark) and no heavy metals or other toxins found.

    #3
    MRMUSCLES
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 18:58:45 (permalink)
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    if the gear does nt kill you it will be the tuna ha ha!
    #4
    Big Les
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 20:24:31 (permalink)
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    Good info Levi
    The US bros get the larger species of tuna canned as well as the tiddlers we get.

    The smaller tuna are fine.

    Swordfish - again havent heard anything yet.

    big les
    #5
    CHTHONIC
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 22:19:40 (permalink)
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    precooking eliminates mercury?
    #6
    Boxer
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 22:26:53 (permalink)
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    quote:
    Originally posted by CHTHONIC

    precooking eliminates mercury?


    Nope.
    #7
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 22:31:31 (permalink)
    #8
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 22:38:16 (permalink)
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    CHTHONIC
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/28 22:48:43 (permalink)
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    Cheers, boxer, so canned tuna still has a fair amount of mercury in it!
    #10
    GTM
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/29 15:24:31 (permalink)
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    Scrap that .... I just read the second link of boxers.. and it would seem that the body does have a mechanism to excrete mercury from the body. Even so it appears to take around 45 days to be excreted. That is a fair amount of time for the body to accumalate it. But it would seem clinical problems are only associated with considerably higher levels than are found in tinned tuna.


    GTM
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    Boxer
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/29 15:26:22 (permalink)
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    quote:
    Originally posted by GTM

    The danger of Mercury is that, being a heavy metal the body has no way of removing it from it's system. Just like asbestos, it accumalates over time. This is where the potential for harm lies. Not in the singular levels found in any particular individual tin of Tuna. Of course the higher those levels are the shorter the duration of consumption needs to be before body levels become high enough to start to cause problems.

    GTM


    Not true GTM. The body completely eliminates mercury after approximately 50 days.
    #12
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/29 15:28:30 (permalink)
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    Toxic Schmoxic

    Q: Everyone at the forefront of nutrition these days in recommending fish oil; however, they all quickly add that it's "toxic." What the heck is going on here?! Should I take fish oil or is the mercury going to kill me? Along those same lines, should I limit how much tuna I eat?

    A: I've got a secret to tell you… Everything's "toxic!" That's right. Everything!
    I'm not allowed to eat lean meat because it contains trace amounts of hormones; I'm not allowed to eat fish because it contains a small amount of mercury (we're talking about fractions of parts per million units, or 0.0000001 units, people!); I'm not allowed to eat fruits and vegetables because they are covered in small amounts of pesticides; I'm not allowed to have sex because the condoms I'm using may deliver a micro dose of environmental estrogens; I'm not allowed to cook my food because that renders the food indigestible; I'm not allowed to own a microwave because it sends off electromagnetic energy that will give me cancer in addition to destroying my food; I'm not allowed to drink tap water, distilled water, cold water, or even filtered water from non-glass containers because I'll be getting too much chloride, fluoride, the wrong ionization, impaired digestion, or chemicals leached from the plastic containers; and I'm not even allowed to type this freakin' article because my computer monitor is sending off both electromagnetic fields as well as toxic chemicals into the air, causing a slow erosion of my health.

    I might as well go back to bed. If I stay there all day, I'll be safe — wont I?
    I've gotta be honest with you. I really hate the way that the health paranoiacs brandish the word toxic as if it was a loaded gun. If I had a nickel for every person that told me that fish oil or tuna or one of a host of other foodstuffs was toxic, I'd be a wealthy man. After all, what exactly are those fear mongers saying when they use the word toxic? To me, it's nothing more than waving their magic paranoid wands over something and making it, from that day forward, synonymous with "bad." When they say fish oil is toxic, they're telling us nothing other than their opinion that it's bad. So rather than saying fish oil is bad, how about discussing what those toxins are and perhaps demystifying them?

    Since fish are part of the food chain, they, like many other foods, are subject to contamination. To this end, the Canadian Food Inspection Agency, and agencies like it across the world (i.e. Britain's Food Standards Agency) take measures to quantify the level of contaminants, or "toxins" and determine whether or not the levels of these chemicals are enough to cause any serious health concern.

    Remember, pretty much everything, especially every food, nowadays, has been linked to some type of cancer or malady. So don't get all worked up when I tell you that fish can contain some contaminants. After all, even if you don't get those contaminants directly from the fish, you'll be getting them from the livestock that eat the fish (fish meal and fish oil are very popular livestock feeds), or diluted in your water supply, or from the fruits and vegetables you eat. Yes, the state of affairs of our environment truly sucks. It sure sucks that our water, our air, and our food is all polluted. And I think it's important to do our own part in seeing that this state of affairs improves. But in the meantime, life must go on and we must make choices as to how to live it.

    So now that we know everything we eat has some contaminants and could therefore technically be described as "toxic," and we know that this is because we have allowed our chemicals to muck up our environment, let's clarify that this description of "toxic" means that the foods contain some substances that can cause harm if consumed in high enough concentrations. With that said, let's discuss which toxins are found in fish and whether they're found in high enough concentrations to be of concern.
    The contaminants usually associated with fish are dioxins and furans, PCB's, DDT, and mercury. To give you some clue of what these compounds are, here's a quick synopsis:

    • Dioxins and furans are components in a group of substances (polychlorinated planar aromatic structures) which have similar physical and chemical properties and consist of 75 polychlorinated dibenzo-para-dioxins (PCDDs) and 135 polychlorinated dibenzofurans (PCDFs). Seventeen members of this group have been studied extensively and are considered "toxic".

    • PCBs are also persistent pollutants, some of which resemble the chemical structure of "dioxin-like" compounds. PCBs differ from dioxins and furans in that they are manufactured for transformers, insulators, capacitors etc., while dioxins and furans are produced unintentionally, as unwanted by-products from various combustion and industrial processes and from natural events like forest fires and volcanic eruptions.

    • DDT is a colorless chemical pesticide, dichlorodiphenyltrichloroethane, used to eradicate disease-carrying and crop-eating insects. Unfortunately, this chemical has been linked to the death of many other animal species, to reproductive abnormalities in wildlife, and even cancer in humans.

    • Methyl mercury is a highly toxic substance; there are a number of adverse health effects associated with methyl mercury exposure. Most extensive are the data for neurotoxicity, particularly in developing organisms.
    Now that's an ugly picture isn't it? Knowing that these substances are found in fish does make me a bit hesitant. But we've gotta put things into perspective here. Most of the studies I've seen indicate that many of the fish oils available on the market today as well as many of the fish meal products contain only small amounts of these 4 toxins, amounts well below the limits at which health concerns might arise. Now remember, just because a food might have some toxins in it, that doesn't mean that it will cause health problems. Just like most drugs have a minimum effective dose, so do toxins. We all know that 1mg of caffeine will do nothing to promote concentration or alertness. But take 200mg and all of a sudden, things start to happen.

    Since you also asked about tuna, I'll address that as well. Yes, tuna contains some mercury. But the levels of mercury contained in tuna are about 1/3 as low as those in fish considered to present a health risk. In addition, canned tuna has much less mercury than fresh tuna, so this bodybuilding staple is probably just about as safe as the next food.
    While it's easy to understand why the health paranoia proponents are cautioning us against this toxic fish or fish oil, we can't let them take the focus off what's important here. Thousands of studies have been done using fish oil (of all concentrations and "purities") and in each study the benefits of the fish oil have manifested in amazing ways. Talk about a panacea for our culture's syndrome x problems! And in the face of this overwhelming evidence in favor of fish oil, there's been very little reported in the way of negative effects.

    But even if the research isn't enough to convince you, how about checking out the health histories of the people with the highest level of deep ocean fish consumption? You won't find a dramatically high incidence of "toxicity." In fact, these people are far healthier than North Americans are.
    At this year's SWIS symposium, everyone recommended fish oil but most of these people also suggested that fish oil was toxic. Interesting that in the face of all of this toxicity, the studies have shown overwhelming benefits anyway, such that the experts are still recommending them.

    Regardless, one thing I did take away from the SWIS symposium, something I've been championing for a long time now, was that you should be getting concentrated forms of EPA/DHA — especially if you're taking a whole lot of it. For example, Barry Sears recommended "pharmaceutical grade" fish oil, which is defined as containing > 60% EPA+DHA, isn't a bad idea. I'm also told that Biotest is coming out with a fish oil that will match or surpass that percentage of EPA +DHA.

    In the end, I've heard all the arguments for and against using fish oil and my conclusion, at this point, is that even if there is potential toxicity (mercury or anything else), the benefits FAR outweigh the risks. So when health experts suggest avoiding fish oil, I think they're doing people a disservice. By creating a big toxin scare they're discouraging the use of the ultra-health promoting oils. They're "muddying the waters," so to speak, and people, in the absence of an expert consensus, do nothing proactive to take control of their health.

    Taken from http://www.johnberardi.com/articles/qa/afc/afc_nov082002.htm
    #13
    Boxer
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/02/29 15:37:26 (permalink)
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    quote:
    Originally posted by GTM

    Scrap that .... I just read the second link of boxers.. and it would seem that the body does have a mechanism to excrete mercury from the body. Even so it appears to take around 45 days to be excreted. That is a fair amount of time for the body to accumalate it. But it would seem clinical problems are only associated with considerably higher levels than are found in tinned tuna.


    GTM


    It says 50 days in this link http://www.ynhh.org/online/nutrition/advisor/mercury.html which confirms the above link I guess.
    #14
    sillynarbie
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/06/02 15:01:45 (permalink)
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    So if its eliminated in 50 days, what exactly is the problem?
    #15
    PJH20
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/06/02 15:14:48 (permalink)
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    how much tuna do you eat in 50 days and will that be too much mercury in your system until it is excreted?
    #16
    Boxer
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/06/02 15:27:57 (permalink)
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    You will know if you have mercury posining as you can't mistake the symptoms as you would become very ill.

    So at your current intake of fish you are fine.

    Remember the benefits of eating oily fish in particular outweigh any negatives of possible contamination ( which is in all our foods by the way ).
    #17
    masryinlondon
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/06/21 14:16:12 (permalink)
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    So 300gms of tuna a day for 7 days a week for 2 months - what that be lethal then? Nothing appears to be certain and the Food Standards Agency's advise appears to be more concerned with pregnant women.
    #18
    Dav
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    RE: Tuna/Swordfish/Shark... Mercury Levels 2004/06/21 14:59:51 (permalink)
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    As mad a hatter eh!! I had a lecture when studying from Dr Neil Ward one of the worlds leading authorities on heavy metal poisoning, he was the lead scientist on the camelford incident when an aluminium compound was dumped into the camelford water supply. He found and atested to the fact that in much of his work the body can cope with toxins as long as it has the raw materials for being able to process them in aluminium's case he found that those with higher supplemental or dietary intake of zinc (works antagonistically to aluminiunm) did not exhibit the awful effects of aluminium poisoning, the same for mercury poisoning but selenium is the mineral that is needed although other nutrients will be also required. Interestingly tuna contains high levels of selenium.
    #19
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