Another favorable mercury/fish study

Training Bodybuilding
1

Here's an article from Scientific American on the mercury/fish study.

"Study Questions Mercury Toxicity in Fish

Fish can absorb toxins from the environment and accumulate them within their flesh to dangerous levels in a process known as bioaccumulation. In particular, there have been numerous advisories warning people--particularly pregnant women and children--to restrict their intake of particular species to limit their exposure to mercury, which has been linked to neurological damage and an increased risk of heart attacks. Now a report published today in the journal Science indicates that the type of mercury present in swordfish and tuna might not be as harmful as previously thought.

Graham N. George, now at the University of Saskatchewan in Canada, and his colleagues bought samples of fresh fish from a market in California. Using X-ray absorption spectroscopy (XAS), the scientists investigated which atoms surround mercury found in muscle tissue and determined that the metal was most often bound to a carbon atom on one side and sulfur on the other. In this form, known as methylmercury cysteine, mercury is less likely to cross cell membranes than it is when present in the form of methylmercury chloride, which is typically used to model its potential toxic effects. Indeed, according to the report, day-old zebrafish larvae tolerated 20 times more methylmercury cysteine than methylmercury chloride. "There may be reason for cautious optimism," George says. "The mercury in fish may not be as toxic as many people think but there is a lot we need to find out before we can make this conclusion."

The scientists next plan to study what form of mercury accumulates in mammals that consume fish containing mercury. "Once we understand how mercury is bound in mammalian tissue," George notes, "we'll be ideally poised to design a drug that could perhaps remove it." --Sarah Graham"

Considering that the toxicity of mercury comes from its denaturation of proteins through the binding of sulfur the study findings make sense. In a way, the fish may be detoxifying the mercury.

The other favorable study, a few years old now, was in JAMA. It found that children who ate fish and were born of women who ate fish had no cognitive deficits.

Here's the abstact.

"JAMA. 1998 Aug 26;280(8):701-7.

Davidson PW, Myers GJ, Cox C, Axtell C, Shamlaye C, Sloane-Reeves J, Cernichiari E, Needham L, Choi A, Wang Y, Berlin M, Clarkson TW.University of Rochester School of Medicine and Dentistry, NY 14642, USA. pdavidson@cc.urmc.rochester.edu

Effects of prenatal and postnatal methylmercury exposure from fish consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study.

CONTEXT: Human neurodevelopmental consequences of exposure to methyl-mercury (MeHg) from eating fish remain a question of public health concern. OBJECTIVE: To study the association between MeHg exposure and the developmental outcomes of children in the Republic of Seychelles at 66 months of age. DESIGN: A prospective longitudinal cohort study. PARTICIPANTS: A total of 711 of 779 cohort mother-child pairs initially enrolled in the Seychelles Child Development Study in 1989. SETTING: The Republic of Seychelles, an archipelago in the Indian Ocean where 85% of the population consumes ocean fish daily. MAIN OUTCOME MEASURES: Prenatal and postnatal MeHg exposure and 6 age-appropriate neurodevelopmental tests: the McCarthy Scales of Children's Abilities, the Preschool Language Scale, the Woodcock-Johnson Applied Problems and Letter and Word Recognition Tests of Achievement, the Bender Gestalt test, and the Child Behavior Checklist. RESULTS: The mean maternal hair total mercury level was 6.8 ppm and the mean child hair total mercury level at age 66 months was 6.5 ppm. No adverse outcomes at 66 months were associated with either prenatal or postnatal MeHg exposure. CONCLUSION: In the population studied, consumption of a diet high in ocean fish appears to pose no threat to developmental outcomes through 66 months of age."

So, if you’re a fish-eater like me things are not likely as bad as the fearmongers claim.

2

muhr, interesting study. I hope the people on here (there are still a few) who cling to their theories that tuna is killing us all will read it also. They never listened to me.

3

Heh.

Fisheater.

Heh.

4

Man during bulking diets I sometimes take in up to 5 cans of tuna a day! I’ve never bought into the whole mercury craze.

5

http://www.sfms.org/sfm/sfm301d.htm

The Danger of Mercury Poisoning From Fish
Jane Hightower, MD

I recently discovered elevated mercury levels in many of my fish-eating
patients…The fish most popular for them are swordfish, Ahi, halibut,
seabass, snapper, sushi and canned tuna. Sixty-two of the patients had [serum mercury] levels >10 mcg/L, 20 were greater than 20 mcg/L, and 4 were greater than 50 mcg/L. The most common symptoms for those affected were fatigue, hair loss, trouble thinking, memory loss, muscle aches and headache. A unique symptom was metallic taste. The levels also did not necessarily correlate to their level of symptoms.

Fish accumulate methyl mercury in their tissues which becomes strongly bound. It cannot be cooked out of the fish. This organic compound is nearly 100 percent absorbed when we eat it. It is lipophilic and can traverse every cell in the body. It is strongly bound to sulfhydril groups in our tissues which gives it a strong affinity for our brain and muscles. It binds to proteins involved with the production of microtubules and, in doing so, interferes with mitoses.

The EPA studied the world’s literature on mercury and their report was released in 1997 as the Mercury Study Report To Congress. Because of delays in its release and other new information Congress asked the National Academy of Sciences to evaluate the literature. Their report was released July, 2000. These two reports confirmed that the “no adverse affect level” for mercury is <5.0 mcg/L whole blood. The “benchmark dose calculation” (how much you can eat), was estimated to be 0.1 mcg/Kg body wt/ day. This is to protect fetuses, infants, children, sensitive individuals and exposure over a life-time. The “fudge factor” is still being debated and can be 3-10 fold, depending on which report you read.

To give an example, salmon has a mercury level on average of 0.035 mcg/g. A 60 Kg person could eat 42 mcg Hg/ week and stay within the current EPA guidelines. This would be about 2 lbs per week of salmon. For swordfish at 1 mcg/g this would be less than 2 ounces per week. or canned tuna at 0.206 mcg/g, a child should not eat more than 1 ounce per 20 lbs. body wt./week. Although the recent warning did not include large tuna, many researchers and advocates, including myself, feel that it should have. Canned tuna is also still being questioned as people eat so much of it.

Dr. Hightower is a board-certified internist, with a private practice in San Francisco since 1991. Her interest in the subject of fish and mercury was inspired by her patients and colleagues who have been questioning their symptoms and Hg levels. She is a member of the SFMS.

6

Nice to see that study, muhr.

I’d read some of the other studies and just basically said to hell with it. Tuna is too clean, and too inexpensive a protein source to avoid.

Now I don’t feel as bad.