Fish

Fish and nutrition

Australia’s leading health research body, the National Health and Medical Research Council (NHMRC), suggests Australians should eat more fish. Fish is nutritious, providing energy (kilojoules), protein, selenium, zinc, iodine and vitamins A and D (some species only).

Fish is also an excellent source of readily available long-chain omega-3 fatty acids, which are well known for their health benefits and are essential for life.

Researchers worldwide have discovered that eating fish regularly – 2 or more serves weekly – may reduce the risk of diseases ranging from childhood asthma, cardiovascular diseases, prostate cancer and other diseases typical of Western societies.

Healthy ways to enjoy fish include baked, poached, grilled and steamed.

Health benefits of eating fish

For optimal health, it is important to include a combination of foods from each of the 5 major food groups every day. Fish is part of the group that includes all kinds of lean meat and poultry, eggs, soy products (tofu), nuts and seeds and legumes or beans.

Foods in this group are sometimes called ‘protein rich’ and include a range of important nutrients and essential fatty acids (‘good fats’). Fatty acids are a component of dietary fats essential for vital functions in our bodies.

There are 2 essential polyunsaturated fatty acids – omega-3 and omega-6. Omega-3 fatty acids are found in plant and marine sources – however it is the fatty acids in fish that appear to be the most beneficial to our health (including reducing our risk of heart disease).

Research suggests regular consumption of fish can reduce your risk of various diseases and disorders. Selected findings include:

• Asthma – children who eat fish may be less likely to develop asthma.
• Brain – fish rich in omega-3 fatty acids can contribute to the health of brain tissue.
• Cardiovascular disease – eating at least 2 serves of fish per week reduces the risk of heart disease and stroke by reducing blood clots and inflammation, improving blood vessel elasticity, lowering blood pressure, lowering blood triglycerides and boosting ‘good’ cholesterol.
• Dementia – elderly people who eat fish at least once a week may have a lower risk of developing dementia, including Alzheimer's disease.
• Diabetes – fish may help people with diabetes manage their blood sugar levels.
• Eyesight – breastfed babies of mothers who eat fish have better eyesight, perhaps due to the omega-3 fatty acids transmitted in breastmilk. Eating fish 2 or more times a week is associated with reduced risk of age-related macular degeneration.
• Inflammatory conditions – regular fish consumption may relieve the symptoms of rheumatoid arthritis, psoriasis and autoimmune disease.
• Premature birth – eating fish during pregnancy may help reduce the risk of delivering a premature baby.

Fish is rich in omega-3 fatty acids

To reduce your risk of heart disease and stroke, the National Heart Foundation recommends 250-500mg per day of long-chain omega-3 fatty acids. This can be achieved by eating a combination of foods from each of the 5 major food groups every day which includes 2 to 3 serves of fish every week and omega-3 enriched food or drinks (such as eggs, bread and milk).

Amount of omega-3 fatty acids in fish

Adding fish to your weekly diet doesn’t need to be expensive. Some of the best sources can be found on supermarket shelves. Oily fish contains at least 10% fat (healthy omega-3 oils), and includes:

• canned sardines
• canned salmon
• some varieties of canned tuna.

Approximate amounts of omega-3 fatty acids (EPA and DHA) per 150g serve of varieties of fish include:

• canned sardines 1,500mg
• salmon (fresh Atlantic or Australian) >500mg
• gemfish (fresh) >500mg
• canned salmon 500–1000mg
• canned tuna 300–500mg
• rainbow trout, flathead (fresh) 300–400mg
• smoked cod 300–400mg
• barramundi, snapper, John Dory (fresh) 200–300mg.

Amount of omega-3 fatty acids in other foods

Approximate amounts of omega-3 fatty acids in other foods include:

• 2 slices of fish oil-enriched white bread 50–120mg
• lean beef or lamb (65g serving) 20–90mg respectively
• one fish oil-enriched egg 125mg
• fish oil-enriched margarine (10g) 60mg
• one regular egg 70–80mg.

Fish oil supplements

Although fish oil supplements might be beneficial in certain cases (such as treating high triglyceride levels), there is no consistent evidence for their use in the general population.

Do not take fish oil supplements unless advised by your doctor. Some vitamin and mineral supplements can interact with prescription medicines and medical treatments.

It is also possible to consume too much omega-3 fatty acids. The upper level of intake is set at 3,000mg per day. It is recommended not to take more than this from capsules without the supervision of your doctor or a dietitian.

Avoid fish high in mercury

While it is recommended to eat 2 or more fish meals a week, it is wise to avoid fish high in mercury. This is especially important if you are pregnant, planning a pregnancy breastfeeding, or have young children (up to 6 years).

Excess mercury appears to affect the nervous system, causing:

• numb or tingling fingers, lips and toes
• developmental delays in walking and talking in children
• muscle and joint pain
• increased risk of heart attack.

Fish high in mercury include shark, swordfish (broadbill) and marlin, ray, gemfish, ling, orange roughy (sea perch) and southern blue fin tuna.

Pregnant women are advised:

• no more than one serve (150g) per fortnight of marlin, shark (flake), or swordfish with no other fish eaten in that fortnight.
• one serve (150g) per week of orange roughy (deep sea perch) or catfish and no other fish that week.

If you catch and eat your own seafood, don’t fish in areas that are likely to be polluted with chemicals – such as urban waterways. Bottom feeder species, such as catfish, may ingest more pollutants.

Types of fish cuts

The types of fish cuts available include:

• fillet – the boneless flank of the fish
• dressed – with head and fins (entrails, scales and gills are removed)
• steak – cross-sections taken from a dressed fish
• gutted – whole fish with entrails removed.

Healthy ways to cook fish

Healthy ways to cook fish include:

• Baking – make shallow cuts along the top of the fish. Put into a greased dish and cover with foil. Flavour with herbs, lemon juice and olive oil. Bake at around 180°C and baste frequently.
• Shallow frying – dry and flour the fish. Place a small amount of oil or butter in the pan. Fry the fish at a medium heat.
• Grilling – cut slashes into whole fish to help the heat penetrate the flesh. Place fish on a preheated grill. Baste frequently.
• Poaching – not suitable for flaky varieties. Place fish in gently simmering stock. Whole fish should be placed in a pan of cold stock, which is then slowly brought up to a gentle simmer.
• Steaming – put fish in a steamer or on a plate over a saucepan containing gently boiling water. Cover.

Cooking times for fresh fish

To estimate the cooking time of a fresh piece of fish, measure the meat at its thickest part. Suggested cooking times include:

• One cm thick – bake for 3 minutes, shallow fry for 4 minutes, grill for 5 minutes, poach for 8 minutes, steam for 3 minutes.
• 2cm thick – bake for 11 minutes, shallow fry for 7 minutes, grill for 6 minutes, poach for 10 minutes, steam for 7 minutes.
• 3cm thick – bake for 15 minutes, shallow fry for 10 minutes, grill for 9 minutes, poach for 12 minutes, steam for 11 minutes.
• 4cm thick – bake for 20 minutes, shallow fry for 13 minutes, grill for 11 minutes, poach for 13 minutes, steam for 14 minutes.

Cooking times for frozen fish

To estimate the cooking time of a frozen piece of fish, measure the meat at its thickest part. Suggested cooking times include:

• One cm thick – bake for 17 minutes, shallow fry for 7 minutes, grill for 12 minutes, poach for 10 minutes, steam for 5 minutes.
• 2cm thick – bake for 22 minutes, shallow fry for 11 minutes, grill for 15 minutes, poach for 15 minutes, steam for 11 minutes.
• 3cm thick – bake for 35 minutes, shallow fry for 15 minutes, grill for 24 minutes, poach for 22 minutes, steam for 13 minutes.
• 4cm thick – bake for 39 minutes, shallow fry for 18 minutes, grill for 28 minutes, poach for 28 minutes, steam for 16 minutes.

Sustainable fish shopping

All fishing has some impact, but some fish choices are far better than others. Some fish types may be overfished, associated with by-catch of birds or mammals (long lines used to catch swordfish also snare turtles, sharks, dolphins and seabirds), or may be killed in the process of commercial fishing for other species.

Learn how to choose sustainable seafood.

Where to get help

• Your GP (doctor)
• Dietitians Australia Tel. 1800 812 942 – find a dietitian near you
• Victorian Fisheries Authority Tel.13 61 86
• Australian Marine Conservation Society – for information about sustainable fishing