Is 1 CAN of Tuna per day harmful?

[Newlife]

I want to know if the mercury and other toxins in a can of tuna would be too much or harmful if you ate a can a day in addition to a clean diet

Thank You.

[I. Kay]

I know MH forum is awfully slow, but I remember some really good discussions and links from that site. I think it was from last year sometime, so you may have to deal with the half-assed search engine.

I believe the general consensus was that it's nothing to worry about. However, there were dissenters.

[Willie T]

Newlife,

I’m not an expert but will share with you my experience.

I started the BFL program 19 months ago and in the first few months of healthy eating and exercise, I felt great. I had new found energy. Sometime in the 5th or 6th month, I began to have 1 can of all white, low sodium tuna with salad for lunch, 6 days a week. About the 8th or 9th month, I began to be tired before the end of the day, angry, and unmotivated. I could not figure out what was wrong until a friend alerted me to the mercury issue in tuna. I denied it because I found tuna a cheap but protein rich source and didn’t want to change. However, I could not deny my lack of energy. I stopped tuna and started another source of protein. Within about a month or a month and a half, my energy level returned. That was about 9 or 10 months ago and my energy level has maintained.

Was it the tuna? Was there mercury in the tuna? I don’t know and I can’t prove it. More empirical evidence is needed.

[I. Kay]

Willie T: Interesting. Do you have any other suspicions as to what may have caused your energy changes? I usually eat 3-4 cans per week, so I assume I'm relatively safe.

[Willie T]

RockHard,

I changed nothing else in my diet, lifting, or cardio during the time mentioned. I have no other suspicions but I can't claim it was the tuna either.

Here's a question for you. Are you eating "all white" tuna and what brand? I don't know that it would make a differance but I'm just curious.

[I. Kay]

I eat Starkist White Albacore, unless another brand is on sale.

[Willie T]

Same for me but mine was low sodium. I ate the low sodium b/c I've read that excess sodium can cause water retention and hide difinition. I try to limit sodium when I can.

I now eat chicken breast 6 days a week. It's more time consuming and expensive. However, I do enjoy it more and like I said, my energy is back.

[Newlife]

Originally posted by Willie T:
RockHard,

I changed nothing else in my diet, lifting, or cardio during the time mentioned. I have no other suspicions but I can't claim it was the tuna either.

Here's a question for you. Are you eating "all white" tuna and what brand? I don't know that it would make a differance but I'm just curious.

Great Info Guys!!

I too eat white albacore, high grade stuff, and rinse and drain it very well. Very interesting...

I think I will go to the damn MH site and search. I swore I was not going to return there, but...

Thanks Again!

[Willie T]

Don't know if you want to just limit your sources to fitness sites but you might take a look at these:

http://www.pbs.org/now/science/mercuryinfish.html

http://www.nrdc.org/health/effects/mercury/tuna.asp

http://vm.cfsan.fda.gov/~dms/admehg3.html

They all recommend no more than 2 cans a week of Albacore tuna (it has the most mercury of the can variety).

[Newlife]

Thank Willie T! Great links...

[Lost Dog]

Originally posted by Willie T:
Newlife,
I started the BFL program 19 months ago and in the first few months of healthy eating and exercise, I felt great. I had new found energy. Sometime in the 5th or 6th month, I began to have 1 can of all white, low sodium tuna with salad for lunch, 6 days a week. About the 8th or 9th month, I began to be tired before the end of the day, angry, and unmotivated. I could not figure out what was wrong until a friend alerted me to the mercury issue in tuna. I denied it because I found tuna a cheap but protein rich source and didn’t want to change. However, I could not deny my lack of energy. I stopped tuna and started another source of protein. Within about a month or a month and a half, my energy level returned. That was about 9 or 10 months ago and my energy level has maintained.

Was it the tuna? Was there mercury in the tuna? I don’t know and I can’t prove it. More empirical evidence is needed.

Mercury poisoning is caused by a buildup of mercury that is not reversable. If you'd seen signs of the mercury causing a problem, stopping the tuna wouldn't help, although it could make it worse if you didn't.

The smaller the fish, the less mercury it contains (bigger fish at many smaller fish and absorbed their mercury, too.). The safer tuna, if you're going to eat a bunch of it, is chunk light, which is from smaller fish. Chunk white is the next best (larger fish). Solid white is from the biggest fish.

[Willie T]

Hi Lost Dog,

Thanks for your reply.

While I do not adamantly disagree with you, I have a hard time accepting that mercury poisoning can not be reversible and that by stopping any poisoning to one’s system would not help.

I say this because there are too many unknown factors. Check out this site:

http://www.noamalgam.com

The main point is:

Problems mercury can cause

Mercury can cause a bewildering variety of problems. In fact, one of the major criticisms of amalgam illness is that it is cited as the cause of so many things. But, like the parable of the blind men and the elephant, mercury can indeed cause many diseases. Modern physicians are not trained to find the root cause of a sick person's problems. They are trained to translate what they see into Latin, look it up in their textbook, and apply a cookbook treatment. With a toxin that poisons fundamental metabolic processes different people will experience different symptoms to start off, depending on their own individual biochemistry. As the poisoning becomes more and more serious, further symptoms surface and the modern doctor adds more diagnoses - a patient who starts with depression might later be considered to have hypothyroidism, allergies and asthma in addition. But no thought is given to why one person should develop more and more "diseases," when a single diagnosis - chronic mercury poisoning - could account for them all.


While this type of mercury poisoning emphases amalgam fillings it is still mercury none the less. I have a few of these type fillings and combined with a daily dose of Chunk white tuna, I think it would be safe to say that no one could say what effect this would have on me or anyone else.

I maybe wrong about all of this because I have read little concerning mercury poisoning but I just find it hard to accept that, stopping increased mercury consumption, eating healthy, drinking a lot of water, lifting, and cardio would not decrease some of the effects. I also think that this life style would help detoxify the body to some degree no matter what type of poisoning one has received. Note that I said ‘hard to accept’ because it may not be reversible and there could be other reasons why I feel better. I would accept it with more evidence (which may be out there and I just am not educated enough on the issue yet). However, I think that most of us would agree that medical science continues to learn how poisons and other substances affect the human body. I remember over the years how doctors changed their minds about eggs being healthy or unhealthy. Maybe science doesn’t know everything at this point about mercury poisoning either.

I look forward to your reply and becoming more informed on this issue.

Willie T

[Lost Dog]

I'm no expert either. But a key difference here is that mercury is a heavy metal that settles into your body's cells and stays there. This is why bigger fish get more and more mercury concentrated in their bodies as they eat more and more smaller mercury containing fish.

Poisons, typically, cause their damage and are flushed from the system (should you live, of course).

[Johnka]

Good discussion guys.

I'll add my 2 cents. In general, I'm unsure about how much tuna can be safely eaten, so I typically don't go over about 5 cans a week. Here is some information that I've accumulated:


Here are the most common health effects of mercury poisoning:

1. Gum problems. The gums become soft and spongy, the teeth get loose, sores may develop, and there may be increased saliva.

2. Mood and mental changes. People with chronic mercury poisoning often have wide swings of mood, becoming irritable, frightened, depressed or excited very quickly for no apparent reason. Such people may become extremely upset at any criticism, lose all self-confidence, and become apathetic. Hallucinations, memory loss and inability to concentrate can occur.

3. Nervous system. The earliest and most frequent symptom is a fine tremor (shaking) of the hand. A tremor may also occur in the tongue and eyelids. Eventually this can progress to trouble balancing and walking.


There are a number of issues to address here. One which surprised me is that there is more mercury in fresh tuna than in canned tuna. In this article: Food Addit Contam 2004 May;21(5):434-40, they found that:

Levels of mercury in the fresh and frozen tuna contained a mean of 0.93 microg g(-1) (range 0.077-2.12 microg g(-1)) and were substantially higher than in the canned tuna (0.15, 0.02-0.59 microg g(-1)).

The same study found that of the varieties of canned tuna, albacore had the highest mercury:

In the canned tuna, mercury concentrations varied with subspecies, with the highest average concentrations being found in Albacore tuna (mean 0.26 microg g(-1), range 0.19-0.38 microg g(-1)) and the lowest (0.047, 0.025-0.069 microg g(-1)) in five samples for which the subspecies of tuna were not identified.

These findinga led some people to conclude that canned tuna was safe, even for pregnant women:

QUESTION: One of my pregnant patients consumes four cans of tuna a week. She became very concerned when she read that tuna contains methylmercury, which is toxic to the fetal brain. How should I advise her? ANSWER: Fresh tuna might contain toxic levels of methylmercury, but levels are much lower in canned tuna. Reassure your patient that eating canned tuna will not harm her or her baby.

Comment In: RefSource:Can Fam Physician. 2003 Feb; 49:141-2; author reply 142/PMID:12619733

As a result, I rarely eat fresh tuna. A recent study examined the mercury levels in various species of tuna from the Mediterranean Sea and found that bluefin tuna averaged 1.18 mg of mercury per kg of fish, and albacore averaged 1.17 mg per kg ( Can Fam Physician 2002 Oct;48:1619-21 )

So an 8 oz. tuna steak would have 270 micrograms of mercury, given the 1.17 mg/kg average. The FDA has set a maximum safe daily mercury exposure rate of .44 micrograms per kilogram of bodyweight. For a 200 lb guy, that's an upper limit of 40 micrograms of mercury per day.

So one tuna steak could go way over that. Of course, I don't know where the FDA got that limit or how flexible it is, and it's probably no problem to eat a tuna steak every once in a while, as long as you're not having steak after steak after steak.

Interestingly, the World Health Organization and the United Nations' Food and Agriculture Organization has set a much lower 'safe limit' than the FDA, for child-bearing women and children: a limit of .23 micrograms per kilo of body weight.

If we can take the averages of the study I mentioned above to be correct, then one can of albacore tuna would have 131 micrograms of mercury, and regular (cheap) canned tuna would have 21 micrograms of mercury. So it would be safe to eat 1 can of normal tuna per day, if you can accept the FDA guidelines, but albacore canned tuna goes over the limit of 40 micrgrams.

If you are worried about unsafe levels of mercury and don't want to give up your 1 can of tuna a day, then apple pectin may provide a little help. In a study of 146 children ( Vopr Pitan 1999;68(1):28-30), apple pectin was found to be effective in mercury intoxication treatment.

[Newlife]

Great Discussion from you both!

Again, THANK YOU.


"As I eat the tuna on my salad"...

[Newlife]

That was great Johnka!