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Greenpeace / Roger Grace

By Rachel Hopkins

Tropical tuna species—skipjack, bigeye and yellowfin tunas—are important economic assets for coastal communities across the globe, and even far from the ocean they are a favorite on supermarket shelves and in sushi bars. These three species—together worth close to $40 billion annually at the final point of sale—prompted eight Pacific island countries to launch World Tuna Day on May 2, 2011. In 2016, the UN officially adopted the date to highlight the importance of sustainable tuna management.

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I couldn't, post-election, muster a plausibly big enough piece of good news to warrant a Thanksgiving blog—but then this morning one arrived. In an astonishingly short eight years, as a result of tougher emission rules on power plants and a declining use of coal, concentrations of mercury in Atlantic Bluefin tuna, the sushi sort, dropped by 19 percent.

There are similar findings for bluefish, but tuna are much longer lived, so the results are extremely surprising—concentrations of mercury in even much older tuna fell at the same or faster rate as mercury concentrations in sea water, suggesting that fisheries contamination can be reversed far more quickly than anyone had dreamed.

Bluefin tuna are still not healthy for women of child-bearing age—and most of the tuna which had led more than 10 percent of U.S. women having unhealthy mercury in their blood is not from the Atlantic ocean, which is healing, but from the Pacific, where coal consumption and mercury loading remains unabated.

Mercury contamination is a serious public health issue. In the U.S. alone, hundreds of thousands of newborns are at risk of lower IQ's from the mercury burden they are born with. Concentrations of mercury have been coming down as a result of broad public education and advisories on which fish to avoid. Overall, mercury emissions in the U.S. have declined sharply as a result of U.S. Environmental Protection Agency regulation.

Now the news from the North Atlantic suggests that globally the epidemic of mercury poisoning can be reversed far more rapidly than scientists had imagined. Requiring the clean up of coal power plant emissions in Asia, the globe's largest remaining source of mercury pollution, will begin to allow Pacific ocean fisheries to recover as well. It's important that countries considering the economics of building coal factor in the almost certain necessity to control for mercury—and when they do, they are likely to find that coal power is no longer economically competitive, so that not only will current plants reduce their emissions, but fewer new ones will make any kind of economic sense—which will be wonderful news for the communities where coal is mined and burned, as well as the climate.

More fundamentally, the North Atlantic story goes at the heart of the popular version of climate denialism—which is the initially plausible notion that the world is so large and each human so small, that it's just not likely that anything each of us does can really change the climate—or poison the oceans. And if we have, it's so terrifying that we really don't believe we can do anything about it. Isn't it too late?

What the declining mercury level in Bluefin tuna shows is that we can—and have—had enormous impacts on the natural world, but that we can, and are, reversing those impacts. Nature, if we stop abusing her, can heal herself not in centuries or even decades, but mere years—even the length of the U.S. president's term.

This is a good news story we need to tell everyone.

EcoWatch Daily Newsletter

By Alina Petre

People generally consider sushi to be nutritious, healthy and rich in omega-3 fatty acids.

However, there are also a few concerns regarding some of the ingredients in it.

People generally consider sushi to be nutritious, healthy and rich in omega-3 fatty acids.iStock

This article takes a detailed look at sushi and its health effects.

It also provides simple tips on how to maximize the health benefits of eating sushi.

What Is Sushi?

Sushi is a popular dish that originates from Japan.

It consists of cooked, vinegar-flavored rice rolled together with raw or cooked fish and vegetables in seaweed known as nori.

It is commonly served with soy sauce, a spicy green paste called wasabi, as well as pickled ginger.

Sushi first became popular in 7th-century Japan as a way to preserve fish.

The cleaned fish was pressed between rice and salt and allowed to ferment for a few weeks until it was ready to eat ( 1).

Around the middle of the 17th century, people started adding vinegar to the rice as a way to reduce the fermentation time and improve taste.

The fermentation process was abandoned relatively recently in the 19th century, when fresh fish started being used instead of the fermented variety. This gave rise to an early version of the ready-to-eat sushi we're now accustomed to ( 1).

Bottom Line: Sushi originates from Japan and consists of a seaweed roll containing vinegar-flavored rice, raw fish and vegetables.

Common Types of Sushi

These are the most common types of sushi ( 1):

  • Hosomaki: A thin seaweed roll containing rice and just one type of filling—for example, an avocado or cucumber roll (photos).
  • Futomaki: A thicker specialty roll that usually contains a combination of rice and several types of fillings (photos).
  • Uramaki: A specialty roll containing several ingredients, but with the seaweed on the inside and rice on the outside (photos).
  • Temaki: A cone-shaped hand roll that holds fillings inside (photos).
  • Nigiri: Mounds of rice covered by thin slices of raw fish (photos).

Sashimi is thin slices of raw fish. It technically isn't sushi, but is often served with it.

Bottom Line: Sushi comes in several different types. The five most popular are hosomaki, futomaki, uramaki, temaki and nigiri.

Nutrient-Rich Ingredients

Sushi is often regarded as a health food, mainly because it contains the following nutrient-rich ingredients.

Fish

Fish is a good source of protein, iodine as well as several vitamins and minerals.

In addition, it's one of the few foods that naturally contain vitamin D (2).

What's more, fish contains omega-3 fats needed for your brain and body to function optimally. They help fight medical conditions like heart disease and stroke (3, 4, 5).

Fish consumption is also linked to a lower risk of developing certain autoimmune diseases, depression and loss of memory and vision in old age (6, 7, 8, 9, 10).

Wasabi

Wasabi paste is often served alongside sushi. It is very spicy, so it is only eaten in small amounts.

It is made from the grated stem of the Eutrema japonicum plant, which is part of the same family as cabbage, horseradish and mustard.

Wasabi is rich in beta-carotenes, glucosinolates and isothiocyanates. Research shows that these compounds may have anti-bacterial, anti-inflammatory and anti-cancer properties (11, 12, 13, 14).

However, due to the wasabi plant's scarcity, many restaurants use an imitation paste made from a combination of horseradish, mustard powder and green dye, which is unlikely to have the same nutritional properties.

Seaweed

Nori is a type of seaweed used to roll sushi.

It contains many nutrients, including calcium, magnesium, phosphorus, iron, sodium, iodine, thiamine as well as vitamins A, C and E (15).

What's more, 44 percent of nori's dry weight is protein, which is comparable to high-protein plant foods such as soybeans (16, 17).

However, one roll of sushi contains very little seaweed, which makes it unlikely to contribute to much of your daily nutrient needs.

Studies show that nori may also contain compounds that have the ability to fight viruses, inflammation and perhaps even cancer ( 18).

Some claim that nori also has the ability to clear heavy metals from the human body.

However, research shows that this property is more likely attributed to brown types of seaweed such as those found in wakame salad ( 19).

Pickled Ginger

Sweet pickled ginger, also known as gari, is often used to cleanse the palate between different pieces of sushi.

Ginger is a good source of potassium, magnesium, copper and manganese ( 20).

In addition, it may have certain properties that help protect against bacteria, viruses and perhaps even cancer ( 21, 22).

Studies further show that ginger may improve memory and help reduce nausea, muscle pain, arthritic pain, menstrual pain and even LDL cholesterol levels (23, 24, 25, 26, 27, 28).

Bottom Line: Sushi contains various healthy and nutrient-rich ingredients, such as fish, wasabi, seaweed and pickled ginger.

Refined Carbs and Low Fiber Content

The main component of sushi is white rice, which has been refined and stripped of almost all fiber, vitamins and minerals.

Some studies suggest that a high intake of refined carbs may promote inflammation and increase the risk of diabetes and heart disease (29, 30, 31).

What's more, sushi rice is often prepared with sugar. The added sugar and low fiber content means that the carbs are broken down quickly in your digestive system.

This can lead to a spike in blood sugar and insulin levels, which has been shown to contribute to overeating in many studies (32, 33).

However, studies also show that the rice vinegar that is added may help lower blood sugar, blood pressure and blood fats ( 34).

Asking for your sushi to be prepared with brown rice instead of white rice can increase its fiber content, nutritional value and reduce the blood sugar spike.

You can also request that your rolls contain a little less rice and more vegetables to further increase the nutrient content and make them feel more filling.

Bottom Line: Sushi contains a large amount of refined carbs. This can make you more likely to overeat and may increase your risk of inflammation, type 2 diabetes and heart disease.

Low Protein and High Fat Content

Sushi is often thought of as a weight loss friendly meal, but it may not be as beneficial as you think.

That's because many types of sushi are made with high-fat sauces and fried tempura batter, which significantly increases the amount of calories you get.

What's more, a single piece of sushi generally contains very little fish or vegetables. This makes it a low-protein, low-fiber meal and therefore not very effective at reducing hunger and appetite (35, 36).

This perhaps also explains why eating a portion of sushi will leave most people still feeling hungry.

To make your next sushi meal more filling, try accompanying it with a miso soup, a side of edamame beans, a portion of sashimi or a wakame salad.

Bottom Line: Sushi often contains high-fat sauces and toppings, but relatively little vegetables or fish. This can easily turn it into a high-calorie meal that's less likely to make you feel full.

High Salt Content

A sushi meal generally contains a large amount of salt.

First, the rice used to make it is often cooked with some salt. In addition, the smoked fish and pickled veggies used to make certain types of sushi also contain salt.

Finally, it's usually served with soy sauce, which is very high in salt.

Too much salt in your diet may increase your risk of stomach cancer. It may also promote high blood pressure in people who are sensitive to sodium (37, 38, 39).

If you want to reduce your salt intake, then you should minimize or avoid the soy sauce, as well as sushi prepared with smoked fish, such as mackerel or salmon.

Although miso soup may help prevent you from overeating, it contains a lot of salt. If you're watching your salt intake, you may want to avoid that as well.

Bottom Line: Sushi can contain a large amount of salt, which may increase the risk of stomach cancer and promote high blood pressure in some people.

Contamination With Bacteria and Parasites

Eating sushi made with raw fish may put you at risk of infection with various bacteria and parasites ( 40, 41, 42, 43).

Some of the species most often found include Salmonella and various Vibrio bacteria as well as the Anisakis and Diphyllobothrium parasites (44, 45, 46, 47).

It's important to note that the U..S Food and Drug Administration does not currently regulate the use of the "sushi grade fish" label. Because of that, this label does not guarantee that the sushi you are eating is safe.

The only current regulation is that certain fish should be frozen to kill any parasites before being served raw.

One recent study examined the raw fish used in 23 Portuguese restaurants and found that 64 percent of the samples were contaminated with harmful microorganisms ( 48).

However, proper food processing and handling procedures can reduce the risk of contamination ( 49, 50).

If you wish to reduce your risk of contamination, aim to eat sushi at reputable restaurants. These are more likely to follow proper food safety practices. Opting for vegetarian rolls or ones made with cooked fish can also be beneficial.

There are some people that may need to avoid sushi made with raw fish. This includes pregnant women, young children, older adults and those with weakened immune systems.

Bottom Line: Improper food processing and handling practices combined with the use of raw fish and seafood increases the risk of contamination with various bacteria and parasites.

Mercury and Other Toxins

Fish can also contain certain toxins due to pollution of the sea.

The best known toxin is mercury.

Predatory fish tend to have the highest levels of mercury.

These include tuna, swordfish, mackerel, marlin and shark. Seafood species that are low in mercury include salmon, eel, sea urchin, trout, crab and octopus ( 51).

Other types of toxins found in fish can lead to ciguatera or scombroid poisoning ( 52).

Sea bass, grouper and red snapper are the most likely to lead to ciguatera poisoning, whereas scombroid poisoning is most likely to result from consumption of tuna, mackerel and mahi mahi ( 52).

You can reduce your risk by simply avoiding the types of fish most likely to be contaminated.

Bottom Line: Certain types of fish are more likely to be contaminated with toxins. This includes mercury and toxins that can lead to ciguatera or scombroid poisoning.

How to Maximize the Health Benefits of Sushi

To get the most health benefits out of sushi, follow these simple guidelines:

  • Increase your nutrient intake. Choose sushi rolls made with brown rice over those made with white rice.
  • Favor cone-shaped hand rolls. Look for temaki on the menu. These rolls contain less rice than more traditional rolls.
  • Increase the protein and fiber content of your meal. Accompany your sushi with a portion of edamame, a wakame salad, a miso soup or sashimi.
  • Avoid rolls made with cream cheese, sauces or tempura. To create crunchiness without these unhealthy ingredients, ask for extra vegetables.
  • Cut down on soy sauce. If you are salt-sensitive, avoid soy sauce or only lightly brush the top of your sushi with it.
  • Avoid certain types of fish. Do not order rolls made with salty smoked fish or fish species at high risk of toxin contamination.
  • Order sushi from reputable restaurants. They're more likely to follow proper food safety practices.

Bottom Line: There are various ways to increase the health benefits of your sushi while reducing the risk of negative effects.

Bottom Line: Is Sushi Healthy or Unhealthy?

Sushi is rich in several vitamins, minerals and health-promoting compounds.

However, not all types are equally healthy or nutritious. Some of them are high in refined carbs and other ingredients that can be problematic.

That being said, if you follow the tips above, then eating sushi can definitely be healthy.

Reposted with permission from our media associate Authority Nutrition.

Sierra Club

Successfully eating with chopsticks will once again be the most nerve-racking part of eating sushi, thanks to a new app that informs and educates consumers about mercury levels in fish. The Sierra Club, the largest and most effective grassroots environmental advocacy group, announced the availability of the Safe Sushi app Dec. 8.

Safe Sushi is an app for people who love to eat sushi and want to be informed about which fish have high levels of mercury. The app can be used in two ways—sushi novices can search by mercury level (high, moderate and low) and sushi connoisseurs can search by the name of the fish.

Safe Sushi is free to download in the Android Market and will be available for free in iTunes Dec. 16.

Mercury is especially threatening to pregnant women and young children. Alarmingly, as many as one in six American women have enough mercury in their bodies to put a baby at risk and more than 300,000 babies are born each year at risk of mercury poisoning. Safe Sushi is a practical tool for women of child-bearing age who want to educate themselves about the types of fish they should or should not consume.

Mercury comes primarily from coal-fired power plants, where it rains down into our rivers and streams and then gets into the fish. When we eat contaminated fish (such as certain types of tuna), it gets into our bodies. Safe Sushi includes a tutorial that illustrates how mercury is absorbed into the atmosphere and moves through the food chain.

The Sierra Club will celebrate Mercury Awareness Week Dec. 5 —11, as President Barack Obama is expected to issue the first nationwide protections against toxic mercury from coal plants Dec. 16. The mercury protections that President Obama is poised to approve would cut 90 percent of toxic mercury from coal-fired power plants, and thereby reduce the amount of toxic mercury in many fish—protecting women and children.

For more information about the Sierra Club, the Safe Sushi app and Mercury Awareness Week, click here.

For more information, click here.

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The Sierra Club is America’s largest and most influential grassroots environmental organization with more than 1.4 million members and supporters nationwide. The Sierra Club works to safeguard the health of our communities, protect wildlife, and preserve our remaining wild places through grassroots activism, public education, lobbying and litigation. For more information, click here.

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