Clean Eating

Tuna: Health Food or Health Pariah?

Winter 2008

Lately, experts can’t seem to agree. To eat tuna or not to eat tuna? That is the great nutrition question. We’ve got the full scoop on how to handle your favorite fish and get those all-important omega-3s.  

Few foods have had a better rep in fitness circles than canned tuna. As a cheap source of unmingled top-notch protein, cans of Bumble Bee and StarKist are as a big a part of gym bags as are stinky sneakers (who could blame canned salmon for plotting an assassination). But here’s the catch. Recent grim headlines about “toxic tuna” may have you thinking something’s fishy. Is tuna a top-notch comestible for building a better body or, with potentially more heavy metal than a Metallica album, should it be left to flounder on store shelves? We’ve gone fishin’ to find out.

The Angel Says

“Tuna remains one of the best bargain low-fat, high-protein foods around.”

With roughly 30 grams of protein - or about 35 percent of the protein a 125-pound active female needs in a day in just 4 low-fat ounces - who can blame the fitness savvy for noshing on copious amounts of tuna week-in and week-out.

“The very high-quality protein found in tuna and other fish is important for building lean body mass, boosting energy levels and improving mood,” says dietitian Susan Kleiner, PhD, owner of High Performance Nutrition in Mercer Island, Washington and author of The Good Mood Diet (Springboard Press, 2007). “Also,” continues Kleiner “data on and off over the years hints that fish protein might be different than other meat proteins in that it stimulates fat-burning.”

While nowhere in the ballpark of Prime Rib, tuna does contain some fat but, according to Kleiner, a good chunk of this is the extraordinarily healthy omega-3 kind. “The omega-3 fats EPA and DHA found only in fish are integral for the health of the nervous and cardiovascular system, the brain and ...ready for this, here it comes… “your mid-section.” That’s right, it appears that fish fat can tilt metabolism in favor of burning fat instead of storing it. Want more? Recent research highlights that EPA and DHA can strengthen bones, fight depression and certain cancers, ward of Alzheimer’s, enhance vision, lower blood pressure, stamp out dry skin, dampen the pain of arthritis and improve cholesterol levels. For pregnant women, these fats are also extremely important for optimal fetal brain development. Who new something could be so naturally talented.

Even though the omega-3s and protein get all the accolades when it comes to tuna, there’s other stuff under those gills worth cheering about. Where better to start than its iron, which helps form hemoglobin, a compound that carries oxygen from your lungs to your working muscles. Rustle up a tuna salad and you’re also rewarded a generous serving of B vitamins that play a central role in energy metabolism. And just 3 ounces of canned tuna forks over a full day’s requirement for selenium. “A really, really important antioxidant that helps eliminate disease-causing free radicals,” Kleiner says.

The Devil Says

“Sorry, Charlie. With sky high mercury levels, tuna should be tossed overboard.”

Holy mackerel! With such an impressive nutrition resume, it’s little surprise health and fitness guru Jennifer Cohen made tuna a dietary staple. So much so that at her tuna apex, the 31-year-old Toronto-based celebrity trainer and former Nike Goddess was downing 1 to 2 cans daily along with frequent trips to her local sushi joint. The outcome of this tuna fixation? “A blood test from my physician that revealed mercury levels a ghastly 28 times higher than what is considered a safe level for an adult female,” sighs Cohen. Dumbfounded, she immediately gave up eating her beloved protein source and has now commenced a ‘boycott tuna’ campaign so more women take heed of the risks of eating large amounts of tuna and, in turn, make wiser seafood choices.

Timothy Fitzgerald, a scientist with the Environmental Defense’s Oceans Program says that being of child-bearing age, Cohen falls into the ‘at risk population’ for mercury toxicity. “Mercury is a potent neurotoxin that builds up in the body over time and does not go away quickly. It is especially dangerous to unborn babies and young children’s developing brains and nervous systems,” says Fitzgerald.

The U.S. Environmental Protection Agency recently reported that up to one in six American women of childbearing age have mercury levels that would put their babies at risk for neurological damage. While Harvard researchers found that mercury exposure during pregnancy was associated with lower infant cognitive scores. Something that is very concerning to Cohen who wants to start a family in the near future. “I wonder how many health-minded women like me there are out there that are eating too much tuna and putting themselves and children at risk.”

According to Fitzgerald, there are also many documented symptoms in healthy adults. “Blurred vision, decline in motor skills, memory loss and tingling of the extremities are common in those with high mercury levels,” reports Fitzgerald. Other evidence suggests that frequent consumption of high-mercury fish may adversely affect the cardiovascular and immune systems. “Despite being very active, I was getting sick a lot and always felt rundown,” adds Cohen. She quietly wonders if swimming in mercury had a lot to do with that.

So how did all that mercury end up in Jennifer’s tuna? Released during the burning of fossil fuels, this heavy metal makes its way into waterways where bacteria transform it into toxic methylmercury. Fish then absorb methylmercury when they feed on aquatic organisms. Big, long-living predatory fish like tuna as well as shark, swordfish, and king mackerel dine on lots of mercury-containing small fish and, over time, accumulate a concerning amount of it. Because it is a common addition to grocery carts, “tuna is one of the biggest ways women accumulate mercury,” reports Fitzgerald. Reason enough to reconsider that tuna casserole.

The Voice of Reason Says

“You can still eat tuna, but tread lightly.”

Being both highly toxic and accumulative, mercury consumption should be limited but, it’s not necessary to blacklist tuna altogether. Just make sure you choose the right species in the appropriate amounts.

Canned Tuna

According to FDA data and a recent study from Rutgers University, canned albacore ‘solid white’ tuna has roughly three times more mercury than pink ‘chunk light’ tuna. Want more cruddy news? The Rutgers study found that 25 percent of the tastier white stuff tested exceeded 0.5ppm – a mercury level that some scientists say is very dangerous. “Albacore tuna has more contaminants because it is a much larger fish than the smaller species skipjack used mostly for light tuna,” says Fitzgerald. But here’s the catch: a Chicago Tribune investigation found that chunk light tuna sometimes contains larger yellowfin tuna – a sub that can bring mercury levels in par with that of albacore canned tuna. Yikes!

Nevertheless, it’s still a safer bet to stick with light tuna or, better yet, switch to canned salmon. Fitzgerald smartly points out that canned wild salmon is not only lower in mercury, it’s also much higher in omega-3 fats. Canned salmon trumps canned tuna in bone-building calcium too, with one serving offering up nearly a third of the recommended daily amount.

Tuna Steaks

A lightly seared tuna steak on the BBQ is fish at its best. But some choices are tantamount to a swimming bullet. “Bluefin and bigeye tuna often contain the most mercury, with bluefin being a very bad ecological choice due to overfishing,” says Fitzgerald. Albacore and yellowfin are next on the risk scale with skipjack posing the least risk. Ahi tuna can refer to either yellowfin, bigeye or albacore. Unfortunately, it’s not always evident which type of tuna you are buying. Rutgers University researchers visited several fish markets and supermarkets in New Jersey and determined that, in most cases, labels gave only a fish name and price. “I would absolutely recommend that consumers ask what type of tuna they are purchasing,” advises Fitzgerald.

Sushi

Low in fat and big on taste, sushi is rapidly becoming one of the most popular figure-friendly options when eating out. But watch out. Spawning controversy, a 2006 investigation of Chicago area sushi found that 10 percent of samples tested were above the 1.0ppm legal U.S. mercury limit set forth by the FDA. What’s more, 70 percent of all samples had mercury contamination levels where women of childbearing age and children would be recommended to eat the fish no more than once per month. “The tuna you most often get at sushi places is yellowfin or bigeye,” says Fitzgerald. These two species (esp. bigeye) can put dangerous amounts of heavy metal into your body if you get on a roll and chow on too much. Err on the side of safety and limit your intake of tuna sushi (a.k.a. nigiri, maki, sashimi) to one or two times a month.

How much can you eat? Use this guide to make sure that you don’t overload on mercury.

0.5ppm is the legal limit for fish sold in Canada and Europe

1.0ppm is the FDA action level for fish sold in the U.S.

A Better Tuna

If you just can’t bring yourself to jump ship with respect to tuna, consider dishing out a few extra greenbacks for the offerings from small-scale canneries. Here’s why:

More Kind-Hearted Fat

“The big tuna companies cook their tuna on board and dump much of the oil into the sea,” suggests Kleiner. They do this because the ‘fishy’ smell is in the fat. Unfortunately, says Kleiner, this means the average supermarket can of tuna has a lot less omega-3 fats than they should. She points out that a 2-ounce serving of a large commercial brand of tuna has half a gram of fat while the same serving from what she refers to as ‘boutique’ canneries can have a hefty 7 grams.

Not-So-Corrupt

Large commercial fisheries aren’t messing around. Bigger tuna translates into bigger profit and, unfortunately, more mercury in your tuna sammie. “Many boutique canneries catch younger, smaller tuna so they have less time to bioaccumulate mercury,” Kleiner points out. Going one step further, some, like the Pacific Northwest St. Jude Fishery, test their catch for mercury to ensure what ends up on store shelves is safe to eat.

Eco-rrific

Large-scale tuna fishing often means longlining - a method of fishing that casts a line with multiple hooks. You end up with lots of tuna and a whole lot of by-catch like sea turtles and sharks that are tossed away. Not exactly environmentally savvy. Small, privately-owned canneries are much more apt to employ minimal by-catch techniques like hand polling and trolling which reel in more sustainable catch sizes and quantities.

A Better Bite

Kleiner believes the fresh taste from tuna that is only cooked once which allows all the natural juices and oils to remain in tact before it’s canned is worth the extra cost alone. The big guys often cook their catch twice, not to mention give it a good freezing. “A 79 cent can of tuna from the supermarket has more mercury, less omega-3 fat and tastes awful. Everything I don’t want,” says Kleiner. Reel in better tuna from these trustworthy sources:

St. Jude (www.tunatuna.com)

Raincoast Trading (www.raincoasttrading.com)

EcoFish (www.ecofish.com)

Vitalchoice (www.vitalchoice.com)

Pacific Fleet Tuna (www.pacificfleettuna.com)

Wild Planet (www.1wildplanet.com)

Mary Lu Seafoods (www.marylouseafoods.com)

Dave’s Gourmet Albacore (www.davesalbacore.com)

Good Fish, Bad Fish

Fish lovers have a lot to be anxious about: PCBs and mercury. Wild or farmed-raised? Sustainably harvested or which ever tastes best? Since seafood is still one the healthiest foods you can slide down your gullet, use this list at your local fishmonger to help steer you away from species that are high in toxins or are being scoop up in environmentally destructive ways. Additionally, these websites will let you determine if your favorite fish is safe to eat or perhaps you should cast your line somewhere else. www.fishonline.org, www.oceansalive.org and www.seafoodchoices.com, www.mbayaq.org/cr/seafoodwatch.asp

Face The Fats

Like Britney Spears emerging from a car with cameas present, omega-3 fats - with their bevy of health virtues - are no strangers to being gawked over. “Adult women should aim for roughly 7 grams of EPA and DHA from fish per week,” advises Kleiner. Here’s which seafood harbor the most: