What are shellfish?
Shellfish are edible fish that are either a shelled mollusc or crustacean. They are eaten in many different ways in various cuisines, depending on their flavour and the style of cooking.
• Examples of shelled molluscs: clams, oysters, mussels and scallops
• Examples of crustaceans: prawns, shrimps, lobsters and crabs
Typically, all shellfish is low in calories and a good source of protein and healthy fats, as well as a good array of nutrients, including as zinc, B12, iron and selenium. They are also more nutritious if they are steamed or baked rather than breaded or fried.
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Where can you buy shellfish?
Shellfish is widely available in the UK. You can buy it fresh or frozen in most supermarkets, local fishmongers and also online delivery companies.
Are shellfish sustainable?
The sustainability of different shellfish varies based on the variety and the country from which they are caught. For example, smaller prawns, such as coldwater prawns or Northern shrimp, are more sustainable than the larger king or tiger prawns, whereas farmed or hand-gathered mussels are the best choice rather than those caught wild, as wild mussel fishing is disruptive to the seabed.
Always look for a sustainability certification when buying shellfish and check the Marine Conservation Society Good Fish Guide for the most relevant information on different shellfish and their current sustainability rating.
You can also read our guide on how to eat fish sustainably for more information.
How to cook shellfish
Cooking styles will vary based on the type of shellfish. Molluscs, such as mussels and clams, need to be prepared before cooking and are typically steamed. You can read more on how to cook mussels in our guide.
Oysters, on the other hand, can be eaten raw or cooked. We have a guide on how to cook oysters for more information, but first you need to know how to open or ‘shuck’ them. You can read our guide on how to shuck oysters if you want to try opening them for yourself.
Crustaceans, such as prawns, crabs and lobsters, are a bit more versatile when it comes to cooking and can be used in a wide variety of different dishes, from curries to salads and barbecues to pastas. They must be cooked first, but can be enjoyed either hot or cold.
Health benefits of shellfish
1. They are high in amino acids
Shellfish – especially crustaceans – are high in amino acids, known as the ‘building blocks’ of protein as we need them for growth and repair and the synthesis of hormones and neurotransmitters.
2. They can help reduce the risk of heart disease
Shellfish, especially mussels, contain polyunsaturated fats (PUFAs) and good levels of omega-3 fatty acid. These PUFAs can help lower LDL (bad) cholesterol and reduce the risk of heart disease.
3. They help support a healthy immune system
Certain shellfish are high in carotenoids, including beta-carotene that converts to vitamin A when consumed. Carotenoids are powerful antioxidants – vitamin A in particular is needed for healthy immunity.
4. Helps protect the skin from ageing
Astaxanthin is a carotenoid that is red-orange and typically seen in the ‘pinker’ shellfish, such as crayfish, prawns and lobsters. This antioxidant helps protect the skin from ageing and maintain moisture and elasticity.
5. May help prevent osteoporosis
Most shellfish are high in vitamin B12, an important nutrient required for healthy bone formation. Low levels of vitamin B12, also known as pernicious anaemia, can increase your risk of osteoporosis as you age.
Potential downsides of shellfish:
Are shellfish high in heavy metals?
Average heavy metal concentrations in shellfish are below maximum limits, making shellfish safe to eat.
Are shellfish contaminated?
By nature of how shellfish live and eat, they do come into contact with various organisms that could be potentially harmful to humans when eaten. That is why it’s really important all shellfish are washed and prepared carefully and cooked thoroughly before consuming. For example, check that fresh mussels are alive when you buy them. Their shells will either be closed or will close when you gently tap them.
Can you be allergic to shellfish?
Yes, shellfish allergies are quite common. Shellfish must be avoided if you have a known allergy. The NHS has more guidance on food allergies if you would like to know more.
Shellfish recipes
This article was published on 6 September 2021.
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 Nutrition and Lifestyle Medicine (BANT) and the Complementary & Natural Healthcare Council (CNHC). Find out more at urbanwellness.co.uk.
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