Sushi: Healthy or Unhealthy?
Written by Alina Petre, MS, RD (NL) — Updated on June 12, 2019
However, this popular Japanese dish often contains raw fish. What’s more, it’s regularly eaten with high-salt soy sauce.
Thus, you may be concerned about some of its ingredients.
This article takes a detailed look at sushi and its health effects.
What is sushi?
Sushi is a seaweed roll filled with cooked rice, raw or cooked fish, and vegetables.
It’s commonly served with soy sauce, wasabi, and 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.
Around the middle of the 17th century, vinegar was added to the rice to reduce the fermentation time and improve its taste.
The fermentation process was abandoned in the 19th century, when fresh fish started being used instead. This gave rise to an early version of the ready-to-eat sushi to which you’re accustomed today.
Sushi originated in Japan and consists of vinegar-flavored rice, raw or cooked fish, and vegetables — all wrapped in seaweed.
Sushi is often regarded as a health food because it boasts several nutrient-rich ingredients.
Fish is a good source of protein, iodine, and multiple vitamins and minerals.
In addition, it’s one of the few foods that naturally contain vitamin D.
What’s more, fish contains omega-3 fats, which your brain and body need to function optimally. These fats help fight medical conditions like heart disease and stroke.
Fish is also linked to a lower risk of certain autoimmune diseases, depression, and loss of memory and vision in old age.
Wasabi paste is often served alongside sushi. As its flavor is very strong, it’s only eaten in small amounts.
It is made from the grated stem of Eutrema japonicum, which belongs to the same family as cabbage, horseradish, and mustard.
Wasabi is rich in beta carotene, glucosinolates, and isothiocyanates. Research shows that these compounds may have antibacterial, anti-inflammatory, and anticancer properties.
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. This product is unlikely to have the same nutritional properties.
Nori is a type of seaweed used to roll sushi.
It contains many nutrients, including calcium, magnesium, phosphorus, iron, sodium, iodine, thiamine, and vitamins A, C, and E .
What’s more, 44% of its dry weight is protein, which is comparable to high-protein plant foods like soybeans.
However, one roll of sushi provides very little seaweed, which makes it unlikely to contribute much to your daily nutrient needs.
Nori may also offer compounds that combat viruses, inflammation, and even cancer. However, the levels of these compounds are probably too low to have any relevant health effects.
Sweet, pickled ginger, also known as gari, is often used to cleanse your palate between different pieces of sushi.
Ginger is a good source of potassium, magnesium, copper, and manganese.
In addition, it may have certain properties that help protect against bacteria and viruses.
Studies further show that ginger may improve memory and help reduce nausea, muscle pain, arthritic pain, menstrual pain, and even LDL (bad) cholesterol levels.
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 and the associated rise in blood sugar levels may promote inflammation and increase your risk of diabetes and heart disease.
What’s more, sushi rice is often prepared with sugar. The added sugar and low fiber content mean that sushi’s carbs are broken down quickly in your digestive system.
This can lead to a spike in blood sugar and insulin levels, which may contribute to overeating.
However, studies also suggest that the rice vinegar added to sushi may help lower blood sugar, blood pressure, and blood fats.
Asking for your sushi to be prepared with brown rice instead of white rice can increase its fiber content and nutritional value.
You can also request that your rolls be prepared with less rice and more vegetables to further increase the nutrient content.
Sushi contains a large number 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 regarded as a weight-loss-friendly meal.
Yet, many types of sushi are made with high-fat sauces and fried tempura batter, which significantly increases their calorie content.
Additionally, a single piece of sushi generally contains very small amounts of fish or vegetables. This makes it a low-protein, low-fiber meal and thus not very effective at reducing hunger and appetite.
To make your next sushi meal more filling, try accompanying it with miso soup, edamame, sashimi, or wakame salad.
Sushi often boasts high-fat sauces and toppings but relatively small amounts of vegetables or fish. The lack of protein and fiber can easily turn it into a high-calorie meal that’s unlikely 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 salt. In addition, the smoked fish and pickled veggies also harbor 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 this ingredient.
If you want to reduce your salt intake, you should minimize or avoid 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 it as well.
Sushi can pack a large amount of salt, which may increase your 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 from various bacteria and parasites.
Some of the species most often found in sushi include Salmonella, various Vibrio bacteria, and Anisakis and Diphyllobothrium parasites.
It’s important to note that the Food and Drug Administration (FDA) does not currently regulate the use of the “sushi-grade fish” label. As such, 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% of the samples were contaminated with harmful microorganisms.
However, proper food processing and handling procedures can reduce the risk of contamination.
To reduce your risk of food poisoning, aim to eat sushi at reputable restaurants that are more likely to follow proper food safety practices. You can also opt for vegetarian rolls or ones made with cooked fish.
Some people — including pregnant women, young children, older adults, and those with weakened immune systems — may need to completely avoid sushi made with raw fish.
Sushi made with raw fish may contain harmful bacteria and parasites. Improper food processing and handling increase your risk of contamination.
Mercury and other toxins
Fish may also contain heavy metals like mercury due to oceanic pollution.
Predatory fish, such as tuna, swordfish, mackerel, marlin, and shark, tend to have the highest levels.
Seafood species that are low in mercury include salmon, eel, sea urchin, trout, crab, and octopus.
Other types of toxins found in fish can lead to ciguatera or scombroid poisoning.
Sea bass, grouper, and red snapper are the most likely to lead to ciguatera poisoning, whereas scombroid poisoning is most likely to result from eating tuna, mackerel, or mahi-mahi.
You can reduce your risk by avoiding the types of fish most likely to be contaminated.
Certain types of fish are likelier to be contaminated with toxins, including mercury.
The bottom line
Sushi is a Japanese roll made from rice, seaweed, vegetables, and raw or cooked seafood.
It’s rich in several vitamins, minerals, and health-promoting compounds.
However, some types are high in refined carbs, salt, and unhealthy fats.
Still, if you’re judicious about how you eat it, sushi can make a great addition to a balanced diet.
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