Seen as a healthy option, sushi has become one of Britain’s most popular foods.
Amazingly, the country’s supermarkets now sell more than 11,000 tonnes every year – mostly to people in search of a tasty and low-fat alternative to a sandwich at lunchtime.
Meanwhile, there are more than 2,800 sushi bars and restaurants around the UK, serving countless colourful variations of the basic rice and raw fish combination which has been a staple of the Japanese diet for centuries.
Thanks to the lean protein from the fish, plus a wealth of micronutrients – provided by the seaweed wrapping, the fish-egg garnish, the spicy wasabi served as a condiment and even the pickled ginger offered as a palate cleanser – sushi is reckoned to be partly responsible for the remarkable longevity in Japan, where record numbers of people live beyond 100.
But not everything served on a sushi menu has equal health benefits – with concerns raised over levels of toxins in some fish and the high calorie count of some of the more processed dishes that cater to modern European and American tastes.
Amanda Serif is a nutritional therapist, a member of the British Association of Nutrition and Lifestyle Medicine – and a massive sushi fan.
She said: ‘Sushi has a well-deserved reputation as a healthy lunch or dinner – combining quality protein and a huge range of really important vitamins and minerals.
‘It’s a good way of helping people eat the recommended two to three portions of oily fish a week. However, the impact on health depends very much what types you choose and how often you eat them.
There are more than 2,800 sushi bars and restaurants around the UK
‘The difference in terms of health benefit is night and day between the more traditional Japanese sushi items and some Westernised versions that contain fried elements and are oozing with mayonnaise and spicy sauce – and, as such, are much more fatty, salty and calorific.’
She also urged caution about the soy sauce which is always served with sushi for dipping.
She said: ‘It’s very tempting to dip the rice into the sauce to soak up as much as possible. But it’s usually very high in salt, which can raise blood pressure. People should dip the fish, not the rice, into the sauce. It offers a perfect sharp counterbalance to the oiliness of the fish – without absorbing as much salt.’
Here the Mail offers a guide to the best and worst options – from ‘the healthiest choice on the menu’ to a dish that’s considered the ‘burger and chips of sushi’…
The healthiest sushi and sashimi dishes
Salmon nigiri
A classic which is found almost everywhere sushi is sold or served, nigiri is a strip of raw fish sitting on a block of sticky short-grain white rice which has been flavoured with tangy rice vinegar.
Ms Serif said: ‘It’s definitely one of the healthiest options.
Salmon is rich in vitamin D, making this dish a great choice
‘Salmon is a high-quality lean protein full of long-chain omega-3 fatty acids – which play a vital role in heart, brain, and eye health.
‘It’s also a great source of vitamin D for immune and bone health, and vitamin B12 which aids the function of the nervous system.’
Although white rice is a good source of energy, it is a refined carbohydrate which – when eaten by itself – causes a spike in blood sugar, leading to inflammation and strain on the body’s system of insulin regulation. But when eaten as part of nigiri, the harmful effects are removed.
Ms Serif said: ‘Because of the protein and healthy fat in the fish, digestion of the carbs is slowed down, so the spike is avoided.’
Tuna naruto roll
Named after the Japanese word for whirlpool – to reflect its swirling circular shape – a naruto roll is raw fish wrapped, not in rice, but in strips of cucumber.
As well as lowering the carbohydrate content, the thinly sliced vegetable adds a refreshing crunch.
Ms Serif said: ‘Like salmon, tuna is a lean protein full of omega-3 fatty acids. It’s also rich in selenium, which is a powerful antioxidant, and vitamin B6 which is great for energy production.
A tuna naruto roll is wrapped in cucumber and suitable for people avoiding carbs
A mackerel temaki roll is a star item on the menu, says our expert
‘A naruto roll is a better choice than nigiri for someone who is managing their blood sugar or who is following a low-carb diet.’
Mackerel temaki roll
A mackerel temaki roll is, according to Ms Serif, ‘the most powerful and healthiest choice on a sushi menu.’
Shaped like an ice-cream cone, it combines raw fish and sushi rice – wrapped in a paper-thin sheet of dried seaweed, known as nori.
She said: ‘Gram for gram, mackerel is one of the richest dietary sources of omega-3 fatty acids, with some research suggesting it can lower levels of cholesterol, improve overall heart health and reduce the risk of cardiovascular disease.’
Meanwhile, the dark-green seaweed is a treasure-house of valuable micronutrients – including higher levels of vitamin C by weight than an orange.
Ms Serif said: ‘You’re only likely to eat small amounts of nori in a sushi meal, but nevertheless it is rich in iron, which is good for red blood cells, and zinc, which is crucial for cell growth and immune function, so it’s a great addition to a nutritious, balanced, diet.’
Battleship ikura
Battleship ikura is a small, hand-pressed oval of rice
Another nutrient-rich feature of sushi menus is ikura – or fish eggs. Battleship ikura (taking its name from its shape) is a small, hand-pressed oval of rice wrapped in a strip of dried seaweed and topped with a pile of eggs.
Usually harvested from salmon, the fish roe also features on other types of sushi, where rice-covered rolls are decorated with a speckling of tiny orange balls.
Although not cooked, the eggs are cured in brine to enhance the flavour and to preserve the signature ‘pop’ they make when bitten.
Ms Serif said: ‘The texture and taste divides opinion. Like with caviar, some people love it, but some people say it turns their stomach.
‘Again, the amounts consumed are likely to be very small in any given meal. But the eggs are still a nutrient-dense food, packed with omega-3, vitamins B12 and D, as well as selenium and other powerful antioxidants.’
The unhealthiest sushi and sashimi dishes
Swordfish sashimi
Swordfish can contain high levels of mercury
Served without rice, sashimi is simply small, neatly-cut, chunks of raw fish. But public health experts warn that some species – especially swordfish, which is a common feature on sushi menus – can pose a significant risk.
Swordfish considered suitable for making into sushi can be 10 feet long and weigh over 500kgs. As ocean predators, they have spent years feasting on smaller fish. And in waters which are contaminated with mercury – either because of industrial pollution or volcanic activity – this means they can accumulate high levels of the toxic chemical in their flesh.
For humans, mercury can disrupt the development of the brain and nervous system in unborn babies and children – as well as harming the nerves, kidneys and heart of adults.
Ms Serif said: ‘Nutritionally, swordfish is an excellent source of protein. But although levels of contamination will vary depending on where the fish was caught, it’s almost impossible to know what those levels are on your plate.
‘The best advice is that swordfish – and other species which are prone to mercury accumulation, such as shark – should only be eaten very occasionally. And for children under 16, or for women who are pregnant or are trying to conceive, swordfish should be avoided altogether.’
California roll
Believed to have been invented on the west coast of America in the late 1960s as a way of making sushi attractive to people who were reluctant to eat raw fish, California rolls – made with the rice on the outside to disguise the seaweed – typically use surimi, or imitation crab meat, as their primary protein.
California rolls are typically made with imitation crab meat which is made from fish paste
Ms Serif said: ‘It’s a processed fish paste which is likely to be fatty and salty, and to contain additives such as emulsifiers, flavourings and colourings. It doesn’t have the same omega-3 benefits as raw fish.’
California rolls typically also contain a higher white rice-to-protein ratio than other, more traditional, types of sushi.
Ms Serif said: ‘The rice is needed to hold it all together. But with more white rice and less quality protein, California rolls are more likely to lead to a blood sugar spike.’
As the body releases insulin in response to the spike, glucose is often cleared too quickly, meaning levels drop below normal, leading to fatigue and hunger.
Ms Serif said: ‘Eating one California roll in a pack of sushi is fine – but if you eat six in one go at lunchtime, the chances are you’ll be dozing at your desk by three o’clock and craving a sugary snack.’
Eel nigiri
Eel in sushi is not served raw as its blood contains a neurotoxin which is poisonous to humans. After it’s been grilled (which removes the poison), the flesh contains many of the same nutritional benefits as other sushi such as salmon and mackerel, and is commonly served as nigiri, on a block of rice.
Eel is not unhealthy, but the sauce it is drizzled with is
This American twist on sushi is typically packed with sugary eel sauce and spicy mayo
However, according to Japanese culinary convention, it usually comes glazed with a rich syrupy sauce made from soy sauce, mirin (a sweet rice wine), and sugar.
Ms Serif said: ‘The sauce adds to the flavour – but it also makes it far more salty and calorific.
‘Sugar in the sauce means extra carbs – in addition to the white rice it’s sitting on. Again, eating one piece of eel nigiri from a pack of sushi is ok… but eating six at a time could mean a significant impact on blood pressure and blood sugar.’
Dragon roll
Originating in the US, the dragon roll is an elaborate and decorative form of sushi – intended to resemble a dragon – with rice on the outside, topped with thinly sliced avocado to look like scales. Often drizzled with eel sauce and spicy mayo, the inside typically features prawn tempura.
It is, according to Ms Serif, ‘the burger and chips of the sushi world.’
She said: ‘Prawn fried in tempura batter is full of fats that can increase cholesterol. And as well as being packed with additives, the spicy mayo and eel sauce mean a slice of dragon roll is likely to contain two or three times as many calories as a piece of salmon nigiri.
‘It may be delicious. But a dragon roll is a long way from the nutritious simplicity of traditional Japanese sushi based on just rice and raw fish: it’s much more processed.’
