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By April Forristall, SeafoodSource assistant editor — 6/25/2009 3:17:19 PM
In 2002, Nick Ralston took a position at the University of North Dakota working with the Environmental Protection Agency-funded Center for Air Toxic Metals Health Effects program. Last week, Ralston and his colleagues published the results of their seven-year-long study, which shows that current U.S. Food and Drug Administration methods for developing seafood consumption guidelines may not provide an accurate assessment of seafood safety. The study's results led them to develop the Selenium Health Benefit Value criterion, which predicts risks or benefits of seafood species based on methylmercury and selenium content. Ralston recently talked to SeafoodSource about the study's implications and what it could mean for the future of FDA's seafood-consumption recommendations.

Forristall: What led to the study?
Ralston: The bulk of the studies (at the University of North Dakota's Energy and Environmental Research Center) have involved studying mercury issues how to capture it, clean it up out of the air. The part that got added when I joined was looking at human health effects. We figured we should get into the biochemistry of mercury, too.

The mercury issue got my attention because I understood the importance of selenium physiology and knew high mercury exposures would cause harm to the brain if it knocked out selenium metabolism. Since I initially though there was far more mercury than selenium in seafood, I thought seafood consumption was causing a lot of harm to children. But after months of full-time research, it became clear that ocean fish contain lots of selenium and relatively little mercury, so I was perplexed about how harmful effects could ever occur. It wasn't until I learned that the studies that had found harm had involved eating whale meat and large sharks that did contain far more mercury than selenium that the story started to become clear.

Why hasn't there been research like this before?
Actually, in 1967, the first study of mercury-selenium interactions showed essentially the same thing that our work shows today. We understand selenium physiology better and can interpret the results better, but some of the early work in the '60s and '70s is hard to beat. Since that time, work on this subject has been largely overlooked or ignored. I am currently writing a manuscript with three of the selenium scientists that did work in this area (they are mostly retired) to get them some of the credit they deserve.

Why hasn't the selenium-mercury issue been more publicized?
For at least the last couple of decades, many have had the problem of dogmatically thinking they knew certain things about the mercury issue for sure. Donmatic thinking always causes trouble and it certainly did in this case. That is why dogmatic thinking is never supposed to be permitted in scientific research. However, politics and policy makers have different agendas and their attitudes toward dogma is quite different than that of scientists. Not wanting to be confused by facts, there has been a long-term tendency to ignore any and all scientific data that got in the way of policy.

Is the FDA taking the research into consideration?
In February, the FDA presented an examination of the data from all the human studies that does a great job of connection all the dots for seafood consumers to consider. Basically, since all the biggest studies show substantial benefits when mothers eat increasing amounts of ocean fish, it's pretty clear the dots are pointing toward encouraging women to increase fish consumption during pregnancy instead of limiting it. They came to the same conclusion as us, but in a different way.

What effect will this study have on the public's perception of the dangers of mercury in seafood?
A lot of people have gotten a completely wrong assumption about what the EPA-FDA advisory actually sys. The current advisory suggests that pregnant women should avoid shark, swordfish, king mackerel and titefish because they contain high levels of mercury. Since we know shark meat can contain more mercury than selenium, I can completely endorse that suggestion. The mercury and selenium levels in the other three varieties on the do-not-eat list need to be examined further before I could comment. However, most people don't understand that the FDA-EPA advisory encourages women to eat up to 12 ounces (two average meals) of ocean fish a week. If the selenium-health benefit values (Se-HBVs) for the various seafood become more widely known, this will make it much easier for women to select ocean fish that are the most beneficial to their children's health. Omega-3 health benefit values (O3-HBV's) calculated in a fashion that is very similar to the Se-HBV's are currently being discussed. And if properly done, these HBVs can be combined to create an overall health benefit value for each of the various varieties of ocean fish.

We developed a way of simplifying how to understand the mercury-selenium issue. If (a species) is not good to eat it will have a negative value. The better it is, the more positive the value; the worse (it is), the more negative. There is a real big contrast to normal types of ocean fish, between 20 and 200. Whales are -100. Seafood with negative values are kind of rare.


New Study Provides Reliable Seafood Consumption Guidelines
Understanding the benefits and safety of eating ocean fish

Grand Forks, North Dakota (9 June, 2009) - A study released this week by the University of North Dakota show that current Food and Drug, Administration methods for formulating seafood consumption guidelines may not provide a reliably accurate assessment of seafood safety.

Results of the study; Selenium-Health Benefit Values as Seafood Safety Criteria, reported in the journal, EcoHealth, (volume 5, number R, pages 442-455) indicate that when mercury levels are measured in fish, the levels of the essential dietary mineral selenium also need to be considered. Since only mercury levels in fish are presently being overstated, and conversely, risks from eating fresh water fish from some locations may be much greater than is currently assumed.

Selenium is an essential nutrient that is required for health of the brain and hormone producing tissues. Mercury binds to selenium with an incredibly high affinity, preventing it from doing its essential functions in the body, especially the brain.

The research team lead by Dr. Nicholas Ralston has previously demonstrated that laboratory animals fed diets with selenium levels approximately equal to those present in ocean fish are more than are many times greater than those that actually occur in ocean fish.

"Since selenium and mercury occur together in seafood but affect health outcomes in opposing directions, it is essential to look at the balance of these elements present in fish," says Ralston.

The study examined a new seafood safety criterion known as the Selenium-Health Benefit Value (or Se-HBV) that predicts risks or benefits of seafoods based on their relative mercury and selenium contents. Foods that contain disproportionately high amounts of mercury have negative Se-HBV's and need to be completely avoided during pregnancy.

However, foods with positive Se-HBV's provide mothers with the selenium their babies need in order to develop healthy brains. Fortunately, only a few seafoods have negative Se-HBV's. For example, among mothers that eat meats of pilot whaled; -85, and larger sharks estimated between -11 and -100, increasing exposures have been found to harm their unborn children. However, most other varieties of ocean fish have highly positive Se-HBV's that are expected to promote child health.

Predictions based on Se-HBV's coincide with findings that children of mothers that eat ocean fish enjoy substantial IQ benefits of up to 10 IQ points, Previous warnings regarding fish consumption have been Based on worst case scenarios projected based on adverse effects of mothers eating foods with negative Se-HBV's.

"Seafood safety criteria based on the Se-HBV will improve protection of public health by properly restricting consumption of hazardous seafoods such as pilot what and shark meats while improving public health by encouraging mothers to eat types of ocean fish that optimize their nutritional status and enhance the IQs of their children," says Ralston.

Proponents of the study, which was funded by the National Oceanic and Atmospheric Administration (NOAA) and the Environmental Protection Agency (EPA), hope the findings will lead to a more balanced approach to seafood consumption guidelines. Particularly those pertaining to pregnant and nursing women.

About the Selenium-Health Benefit Value Study

The Selenium-Health Benefit Value Study (Se-HBV) was proposed by Dr. John Kanelkp and Dr. Nicholas Ralston (Biol. Trace Elem. Res. 2007, 119,242-54) to provide a reliably accurate and easily understood assessment of seafood safety for consumers.

Because it considers both the health benefits of selenium as well as risks of methylmercury, the Se-HBV index provides far more accurate predictions of seafood benefits and safety than current criteria which are based on mercury alone.

Pilot whale meats that were eaten by mothers in the Faroes study that form the basis of current U.S. Environmental Protection Agency advisories regarding seafood safety. However, studies of the effects of maternal ocean consumption are finding IQ benefits of up to 10 points in children of mothers that eat increasing amounts of ocean fish.

What is Selenium?

Selenium is an essential mineral nutrient required for vital bodily processes that are especially important in the brain and hormone producing tissues. Once in the body, selenium becomes incorporated in enzymes (selenoenzymers) that provide vital antioxidant protection in the brain in addition to aiding thyroid and immune system function.

Ocean fish are particularly rich in selenium. Out of 1,100 foods that have been analyzed for selenium by the U.S.D.A., oceans fish comprised 17 of the 25 best dietary selenium sources.

What is Mercury?

Mercury is a naturally occurring element that originates form geothermal sources, but once released into the air, it is rapidly distributed around the world until it falls to the ground where it accumulates in plants and animal materials, Mercury present in these materials is released back into the air when these materials are burned in grass or forest fires, or become retired from circulation if they become buried. Large amounts of mercury released from volcanic activities during prehistoric times became retained in fossilized materials that turned into coal.

When coal is burned, the mercury that had been fossilized in these materials for millennia is released back into the air and becomes actively distributed throughout the environment once more. Airborne mercury that deposits and accumulates in plants and animals becomes more concentrated in the food web, especially in aquatic environments. As a result, nearly all fish and shellfish contain traces of methylmercury. However, larger and older predatory fish have the highest levels of methylmercury.

Available for Interview

Dr. Nicholas Ralston
Energy and Environmental Research Center
University of North Dakota

Wayne Heikkila - Executive Director
Western Fishboat Owners Association
   

 

HOW TO IDENTIFY
Troll-Caught Albacore Tuna

Most canned "white meat tuna" sold in North America today by the major US tuna companies comes from older larger albacore caught in deep waters. Only a small amount of the younger, tastier, Omega-3 rich albacore is available on supermarket shelves - and worse, it's not properly marked on the label!

However, there is an easy way for you to instantly recognize any younger troll-caught canned albacore that may be available on supermarket shelves: simply look at the nutrition label on the back of each can. Notice that older albacore packed in water will show a total fat content of 2 grams or less.

 
2g or less total fat on label indicates older albacore with drier meat

Nutrition Facts Amount/
Serving
%DV' Amount/
Serving
%DV'
Serv. Size 2oz Drained (56g- about 1/4 cup)
Servings about 2.5
Calories 70
   Fat Cal. 10
*Percent Daily Values (DV) are based on a 2,000 calorie diet.
Total Fat 1.0 g 2% Total Carb. 0g

0%

Sat. Fat 0 g 0% Fiber 0g 0%
Cholest. 25 mg 8% Sugars 0g  
Sodium 250 mg 10% Protein 15g 27%  
Vitamin A *% , Vitamin C *%, Calcium *%, Iron *%
*Contains less than 2% of the Daily Value of these nutritions.

However, a can of younger, Omega 3 rich troll-caught in water or natural juices will have at least 3 to 5 grams of total fat.

     
3 - 5g total fat on the label indicates younger Omega -3 rich troll-caught albacore

Nutrition Facts Amount/
Serving
%DV' Amount/
Serving
%DV'
Serv. Size 2oz Drained (56g- about 1/3 cup)
Servings about 3.5
Calories 100
   Fat Cal. 45
*Percent Daily Values (DV) are based on a 2,000 calorie diet.
Total Fat 5.0 g 7% Total Carb. 0g

0%

Sat. Fat 15 g 6% Fiber 0g 0%
Cholest. 20mg 7% Sugars 0g  
Sodium 75 mg 3% Protein 14g 27%  
Vitamin A *% , Vitamin C *%, Calcium *%, Iron *%
*Contains less than 2% of the Daily Value of these nutritions.
 

HIGH SEAS ALBACORE CONTAINS
2200mg OF OMEGA 3 PER SERVING

The higher total fat content on the label reflects the Omega 3 essential fatty acids. Also, not only will you taste the difference, there's an added plus: you will find yourself using less mayonnaise or other added less-healthy oils when using troll-caught in your favorite recipes, since the younger fish are not nearly as dry as the more common older, larger albacore.


The obvious advantage is that heart disease and cancer-fighting Omega 3s
end up replacing saturated fats or unhealthy oils in your cooking without sacrificing taste.

SELENIUM IN TUNA
Protects Against Mercury

Yellowfin tuna was first shown in 1972 to protect against mercury toxicity, not cause it. Further studies by Dr. Howard Ganther and his team at the University of Wisconsin led them to conclude that the rich levels of selenium in tuna were responsible for the protective effect.

Selenium, an essential element in our diet, is vital to the body's antioxidant system and proper immune system function. It has anti-cancer effects and is known to detoxify metals including mercury. It has been shown to protect against mercury in every animal model tested.

If the ratio of selenium to mercury determines if a food is safe, what are the ratios in Hawaii fish? In a Hawaii Seafood Project study supported by NOAA, Dr. John Kaneko of PacMar Inc. in Honolulu and Dr. Nick Ralston of the Energy and Environmental Research Center in North Dakota analyzed selenium and mercury in 15 pelagic fish species caught near Hawaii. They found that all of the tuna and billfish species and most other pelagic fish species contained an excess of health promoting selenium over mercury content. Mako shark was the only fish in the study that had more mercury than selenium. For this reason, most Hawaii fish are not only a healthy source of high quality protein and omega-3 fatty acids; they are also excellent sources of selenium. Our favorite fish are more likely to protect against mercury toxicity, than cause it.

The good news for Hawaii seafood lovers
- the selenium is in every bite!


Molar concentrations of mercury and selenium in 15 Hawaii fish species expressed as means + standard deviations.
Regardless of the amount of mercury, if the selenium level is higher, the fish is safe to eat. In the above figure, molar concentrations of mercury and selenium in 15 Hawaii fish species are expressed as means + standard deviations.


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