Fish and omega-3 fatty acids and cancer risk

Oily fish including swordfish, Atlantic salmon, gemfish, Spanish mackerel and canned fish such as sardines, salmon and tuna are rich sources of omega-3 fatty acids.

There are also a range of plant sources of omega-3 fatty acids, including canola oil and margarine, soybeans, soybean oil, linseeds (flaxseeds) and linseed oil, walnuts and walnut oil and leafy vegetables.

Does eating fish reduce the risk of cancer?

Human studies suggest that eating fish and omega-3 fatty acids may protect against cancer. Research suggests that there is limited suggestive evidence that eating more fish may protect against liver and bowel cancers.

There are other benefits to consuming fish, including reduced risk of developing dementia in older adults, a reduced risk of cardiovascular disease, stroke, and age-related macular degeneration in the eyes.

How much fish should you eat?

Cancer prevention recommendations that are based on strong evidence do not include eating fish because the evidence is not yet strong. However because of the overall health benefits of fish and omega-3 fats, Cancer Council recommends:

Eating fish (preferably oily) at least twice per week; and
Including some plant foods and oils rich in omega-3 fats in your diet.

How to boost fish and omega-3 fat intake

Practical and healthy ways to increase the intake of omega-3 fats in the diet include:

Have grilled or steamed fish with vegetables for dinner.
Use fish in mixed dishes such as curries, stews, casseroles, pastas and soups.
Use canned fish to make fish cakes and serve with vegetables.
Mix canned fish through salad.
Use canola oil in cooking or canola-based margarine.
Choose soy and linseed bread.
Add whole soybeans or tofu in stews, stir fries or soups.
Eat a small handful of walnuts as a snack.
Include walnuts when making homemade breads, muffins and cakes.
Include green leafy vegetables such as broccoli, cabbage and spinach in mixed dishes like curries and stir fries.
Make green frittata.

Mercury and fish

Some types of fish can contain high levels of mercury. High levels of mercury are known to damage the nervous system. Therefore eating fish that contain high levels of mercury every day or in large quantities could be harmful. This is especially a concern for children and women who are pregnant or intending to become pregnant.

Cancer Council encourages all people to follow Food Standards Australia New Zealand (FSANZ) recommendations about consumption of fish high in mercury.

Cantonese-style salted fish

There is strong evidence that consuming Cantonese-style salted fish increases the risk of nasopharyngeal cancer. There is strong evidence that consuming foods preserved by salting (including pickled vegetables and salted or dried fish, as traditionally prepared in East Asia) increases the risk of stomach cancer.