Is sushi good for you, and which types are the healthiest? We asked nutritionist Nicola Shubrook to cast a critical eye over this Japanese staple.
What is sushi?
Sushi is a traditional Japanese dish that's based around a particular variety of short-grain rice that's lightly vinegared and served with a selection of raw or cooked fish and vegetables. Toppings and fillings can include sushi-grade raw fish, such as salmon or tuna, cooked fish or shellfish, tofu, avocado, chicken, vegetables and wasabi.
There are many varieties of sushi, including:
- Sashimi – this is usually slices of sushi-grade fish, which are served on their own, without rice. There are a few cooked versions of sashimi, including squid, crabmeat and tiger shrimp.
- Maki – these tend to be sushi rolls made with rice and a filling, such as avocado and salmon, and then wrapped in seaweed. Sometimes this is then rolled in sesame seeds.
- Uramaki – like maki rolls but the rice is on the outside and the seaweed is on the inside, wrapped around the filling.
- Temaki – this is sushi that has been folded into a cone shape, and is often wrapped in seaweed.
- Nigiri – sashimi that is served on top of a rectangle of rice.
What are the benefits of eating sushi?
Sushi can be a healthy choice, but it depends on the variety you order. Oily fish such as salmon and tuna contain omega-3, which is an essential fatty acid. The World Health Organisation recommends eating 1-2 portions of oily fish a week, so sushi can be a delicious way to reach these targets.
Commonly used vegetables include cucumber, aubergine and avocado. Aubergines are a good source of fibre, vitamins B1 and B6, and potassium. Avocados are an excellent source of monounsaturated fat and vitamin E.
Seaweed is also used in sushi, both as dried sheets used to wrap around the rice (nori) or in salads (wakame). Seaweed is high in fibre and protein as well as being a good source of minerals including iodine, iron, zinc and vitamin B12. Read more in our guide to the health benefits of seaweed.
Which sushi ingredients aren't as healthy?
Sushi rice is often made 'sticky' with a combination of vinegar, sugar and salt, which will increase your total intakes of sugar and salt for the day.
Soy sauce is often very high in salt, so it's worth keeping an eye on how much you use. Just one teaspoon of soy sauce may have up to 15% of your recommended daily salt intake.
Some varities of sushi or accompanying dishes are made with mayonnaise or deep fried in batter. This can dramatically increase the levels of saturated fats in your meal.
Should we be concerned about mercury levels in fish?
The main concern with eating sushi is that it may contain high levels of mercury. A 2014 study by the International Journal of Hygiene and Environmental Health found that blood levels were higher in mercury with weekly consumption of certain fish, including tuna steak and sushi.
It would appear that some fish that we eat here in the UK does contain small amounts of mercury, and that bluefin tuna and Spanish mackerel are likely to contain more mercury than salmon.
There still isn’t enough research yet to support whether wild or farmed fish is better for us, so it would be advisable to stick to the NHS recommendations that we eat two portions of fish a week, of which one should be oily fish, whether it is wild or farmed.
The NHS recommends that adults, including breastfeeding women, should eat no more than one portion of swordfish, shark or marlin a week, and that children, pregnant women and those trying to conceive should avoid these fish altogether in order to prevent mercury being an issue to health.
If you're pregnant or trying to conceive, you should also be careful with tinned tuna and ensure that you have no more than four tins of fresh tuna steaks a week because of the mercury levels. Otherwise, there is no limit on tuna for adults or breastfeeding women.
Who should be cautious about eating raw fish?
Women who are trying to get pregnant, are pregnant or breastfeeding, and children under the age of 16 are advised to avoid eating raw fish such as swordfish, shark or marlin as it's these types of fish that tend to be higher in mercury.
Raw fish in pregnancy should also be avoided as it carries an increased risk of food poisoning.
How to make a healthy sushi order
Keep rice to a minimum and look for the fresh fish and sashimi-style dishes, or those wrapped in seaweed. Add some miso soup and edamame beans for extra health benefits, too.
Don’t go mad on the soy sauce and avoid any deep-fried dishes or mayonnaise-heavy dishes.
Keep an eye on portions. It’s very easy to think you’re not eating a lot when sushi comes in bite-size pieces, but the calories and salt content could soon start to add up once you eat more than 8-10 pieces.
Healthy sushi recipes
Enjoyed this? Now read...
This article was published on 11th October 2018.
Nicola Shubrook is a nutritional therapist and works with both private clients and the corporate sector. She is an accredited member of the British Association for Applied Nutrition and Nutritional Therapy (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at urbanwellness.co.uk.
All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other healthcare professional. If you have any concerns about your general health, you should contact your local healthcare provider. See our website terms and conditions for more information.