What are shellfish?

Shellfish are aquatic animals that have a shell. Most live in salt water but some species may be found in fresh water. Shellfish, and seafood in general, provide an ideal package of nutrients and make an important contribution to a healthy diet. For this reason we are advised to eat two portions per week, with one being rich in the healthy omega-3 variety of fats.


Shellfish are eaten in many different ways in various cuisines, depending on their flavour and the style of cooking. All shellfish are low in calories, and a good source of protein and healthy fats; they provide a wide array of nutrients, including zinc, vitamin B12, iron and selenium. Shellfish are most nutritious when steamed or baked rather than breaded or fried.

Types of shellfish

Shellfish are divided into two main types:

Shelled molluscs:

  • clams
  • oysters
  • mussels
  • scallops


More like this
  • prawns
  • shrimps
  • crayfish
  • lobsters
  • crabs

Health benefits of shellfish include:

  1. Rich in amino acids
  2. May reduce the risk of heart disease
  3. May support the immune system
  4. May protect the skin from ageing
  5. May support bone health
  6. May support healthy weight
  7. May support brain health
  8. May support joint health
  9. May protect your vision
  10. May support the thyroid

Discover more great guides on our healthy hub or check out the health benefits of oily fish and the health benefits of prawns.

Are shellfish sustainable?

The sustainability of shellfish depends on the variety, the country of origin and the method with which they are harvested. For example, smaller prawns (such as cold-water prawns or Northern shrimp) are more sustainable than the larger king or tiger prawns; farmed or hand-gathered mussels are a more sustainable choice to those caught wild, as wild mussel fishing may disturb 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, including current sustainability ratings.

Check out our expert guide on how to eat fish sustainably.

Cooking clams

How to cook shellfish

Cooking styles 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 about how to cook mussels in our cooking guide.

Oysters may be eaten raw or cooked. We have a guide on how to cook oysters, but first you need to know how to open or ‘shuck' them. You can read more about this in our guide – how to shuck oysters.

Crustaceans, such as prawns, crabs and lobsters, are a bit more versatile when it comes to cooking and can be used in a variety of dishes, from curries to salads and barbecues to pastas. They must be cooked first, but can be enjoyed hot or cold.

Find recipe inspiration here.

Health benefits of shellfish

1. Rich in amino acids

Shellfish – especially crustaceans – are high in amino acids. Known as the ‘building blocks’ of protein, amino acids are necessary for growth and repair as well as for the synthesis of hormones and neurotransmitters.

The protein provided by shellfish is also highly digestible because of its low connective tissue content. This makes shellfish a useful food source for the elderly, who need higher protein levels to maintain muscle mass.

2. May reduce the risk of heart disease

Shellfish, especially mussels, contain polyunsaturated fats (PUFAs) and good levels of omega-3 fatty acids. These PUFAs may help balance cholesterol levels and reduce the risk of heart disease.

3. May support the immune system

Certain shellfish are rich in protective carotenoids, including beta-carotene that converts to vitamin A when eaten, and which supports healthy immunity. Shellfish are also a useful source of the mineral selenium, which plays an important role in immune health.

4. May protect the skin from ageing

Astaxanthin is a carotenoid that is red-orange in colour and is typically seen in the more pink shellfish, such as crayfish, prawns and lobsters. This antioxidant helps protect the skin from ageing and supports hydration and elasticity.

5. May help support bone health

Most shellfish are a good source of vitamin B12, an important nutrient required for healthy bone formation. Low levels of vitamin B12 may increase your risk of osteoporosis as you age. Shellfish also provide bone-healthy nutrients such as vitamins A and D and potassium.

6. May support a healthy weight

Shellfish are low in calories, rich in protein and a useful source of healthy omega-3 fats, making them an appropriate food for weight management.

7. May support a healthy brain

Being a useful source of vitamin B12 and omega-3 fats makes shellfish of potential benefit for supporting brain health and cognitive function.

8. May support joint health

Omega-3 fatty acids have an anti-inflammatory action and have been shown in several studies to offer protection for joints.

9. May protect your vision

Regularly eating shellfish and fish appears to reduce the risk of age-related macular degeneration and supports eye health.

10. May support the thyroid

Shellfish are a useful source of iodine, a trace mineral needed by the thyroid for metabolism. They also supply the amino acid taurine, which appears to support thyroid function in those with thyroid conditions.

Can shellfish be bad for you?

Although generally safe for consumption, shellfish can grow in certain unhealthy habitats, or be exposed to some unhealthy farming and handling practices. The filter feeding nature of oysters, clams and mussels may also occasionally present health risks.

These may include:

Heavy metals – shellfish may accumulate heavy metals from their environment. However, levels are monitored and the average heavy metal concentrations in shellfish are currently below maximum limits, making shellfish safe to eat.

Contamination the nature of how shellfish live and eat means they may come into contact with various organisms that could be harmful to humans when eaten. That is why it's important that shellfish are washed, prepared carefully and cooked thoroughly before eating. 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.

Allergies shellfish allergies are common. If you have a known allergy, you must avoid shellfish.

Check out the NHS guidance on food allergies.

Shellfish recipes

Squid, prawn & chickpea nduja stew
Thai prawn & ginger noodles
Mussels with leeks & saffron
Crab & tangled asparagus salad on toast
Oysters with chilli & ginger dressing
Lobster rolls
Speedy spaghetti with clams

Enjoyed this? Now read…

10 healthy fish to eat
Top 5 health benefits of salmon
Top 10 sources of omega-3

This article was reviewed on 6 February 2024 by Kerry Torrens.

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.


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.

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