Fish Oil - Part 1

Walk into a supermarket or chemist these days and you'll be bombarbed with more vitamin supplements than you can poke a stick at. One of the supplements that seems to be in right now is fish oil, so I asked my dietitian friend Sal to give me the low down on what it is, do we actually need it, and if so, how much should we be taking? Here's the scoop.

Sally Marchini

Sally is an Accredited Practicing Dietitian after successfully completing the Bachelor of Nutrition and Dietetics at the University of Newcastle.

Having lived with diabetes and coeliac disease for many years, Sally is passionate about helping other people with these conditions and is opening a private practice in Swansea, NSW as a specialist dietitian.

Connect with Sally on LinkedIn, Facebook & Twitter

Before studying to become a dietitian I often used to wonder about fish oil:  what it was that made it so healthy, how it worked to be healthy for so many parts of our body, what these EPA and DHA letters were all about and what difference they made to me, what’s the best way to have it, how much of it should I have – that sort of thing.  So, I thought I’d write something for you all along those lines in case you have similar wonderings about this quite complex subject.

I’ll start by explaining briefly what omega-3 fatty acids are, then the variety of health benefits that can be gained by consuming fish oil and three of its active components (EPA, DHA & DPA), what the best sources are, and how much we need to consume for the health benefits to be realised.  In my next blog I’ll discuss some of the other issues associated with fish oil such as whether there are differences between wild and farmed fish, fish oil and krill oil, sustainability of seafood in general, and safety relating to mercury levels in deep sea fish and fish oils. 

Omega-3 fatty acids

In the deep cold sea, fish need a kind of ‘anti-freeze’ to allow them to survive.  It is the omega-3 polyunsaturated fatty acids (PUFAs) that do that job for them.  Interestingly these omega-3 PUFAs that we associate with fish originate in the plant form of microalgae.  Deep sea foraging fish (like sardines and herring) eat the microalgae and accumulate the omega-3 fatty acids.  In turn, these fish are eaten by the larger predatory fish like tuna and salmon.  It is this ability of the fish to accumulate the omega-3 PUFAs that makes them special.

In our human bodies fatty acids provide energy, protection, and transmission of messages to and between the millions of cells.  Omega-3 fatty acids are considered essential in our diet as the human body cannot produce them itself. The three of those fatty acids are most talked about are known as EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid) and DPA (docosapentaenoic acid).  Each of these play specific roles in our health, however are generally available together in oily fish such as mackerel, herrings, sardines, salmon and tuna and other seafood. The plant-based Alpha-linolenic acid (ALA) also has many health benefits (found in legumes, canola oils and margarines, linseed oils, certain nuts such as walnuts, and in small amounts in leafy vegetables) but does not benefit human health as well as marine n-3 PUFAs for certain conditions. For those with seafood allergies, marine algae are a viable alternative although an expensive one.

Health benefits that can be gained by consuming fish oil


These omega-3 fatty acid components in fish oil provide several properties that have also been proven effective in humans including:

·       Anti-inflammatory properties that help the immune system, heart health (by decreasing the risk of Coronary Heart Disease, decreasing arrhythmias, and slightly lowering blood pressure) and that help reduce the swelling and stiffness associated with arthritis and other inflammatory conditions

·       Anti-coagulant properties that reduce the risk of stroke, thrombosis and again help heart health

·        Being known to help with high cholesterol by increasing the good cholesterol (HDL), increasing the size of the bad cholesterol particles(LDL) making them less dangerous, and reducing the triglycerides

·         Helping with building and maintenance of neural pathways in the brain, being linked with lower levels of depression and helping with ADHD in some cases

·         Being linked with increased UV protection for our skin and improved breathing for those with asthma

·         Decreasing colonic damage and inflammation in people with Irritable Bowel Disease

·         Reducing insulin sensitivity for people with or at risk of Type 2 diabetes

How much do we need?

The Heart Foundation currently recommends that the adult population of Australia should consume about 500 milligrams of omega-3 (marine source) every day.  On some days you may consume more or less omega-3s than on other days, but aim to consume about 3500 milligrams of EPA and DPA over the whole week.  The Heart Foundation and the Dietitians Association of Australia (DAA) recommend that you achieve this amount by eating two to three serves of oily fish every week and supplementing your intake with fish oil and/or foods and drinks enriched with omega-3.  So, if you were relying entirely on supplements then two 1000mg capsules per day (each 1000mg usually contains 300mg of marine triglycerides) should be ample.

It’s also worth noting at this point that omega-6 fatty acids (found in safflower, corn, sunflower, peanut and other vegetable oils) actually compete with the omega-3s and generally cause an opposite effect in our cells, so choose olive oil in preference to those to obtain an improved benefit.

The Heart Foundation also advises that even though fish sources of omega-3s have great benefits for heart health, pregnant and breastfeeding women must not consume more than the recommended amounts of the larger predatory fish due to the risk of consuming too much mercury (this will be covered more in the next blog). Requirements for specific health conditions will need to be worked out for individuals by an Accredited Practising Dietitian (APD) or other health professional.

Best sources

This table (data taken from the Heart Foundation) gives you a feeling for the levels of Omega-3 in some more common Australian seafoods.  Each listing contains at least 200mg EPA+DHA/150g serve.

EPA+DHA levels per 150g serve

200-300mg /150g serve	300- 400 mg /150g serve	400-500 mg /150g serve	300-500 mg /150g serve	>500 /150g serve
Australian bass	Smoked cod	Australian sardine	Green Mussels	Atlantic salmon
Snapper	Rainbow trout	Yellow-tail kingfish	Oyster, Pacific, raw	Blue mackerel
Silver trevally	Flathead: deep water,	Australian herring	Scallops	Australian salmon
King Dory	southern sand, tiger	Sea mullet	Blue Mussels	Blue-eye trevalla
Whiting	Mirror dory	Silver perch	Crab, blue swimmer	Oyster, Sydney rock
John Dory	Jack mackerel	Some canned salmon and tuna	Baby octopus	Squid, arrow
Other white fleshed fish	Grey morwong		Some canned salmon and tuna	Some canned salmon and tuna

Some ideas to increase your intake might be to include a serve of canned salmon or sardines, which have very high omega-3 levels, and adding another serve of oily fish or seafood (either caught or bought) to your weekly eating plan to help you to reach your weekly omega-3 targets.

It is easy for children to meet recommended intakes of omega-3s. Based on recent Australian Government dietary intake recommendations,  one small serve (100 grams) of a fish such as flathead, plus two small cans of sandwich tuna a week, will provide a child up to age 14 with an adequate intake (AI) of omega-3s.

There is also a wide range of products available that have been fortified with marine-based omega-3s including eggs (chickens fed on fish meal), bread, dairy products, oil and even ice cream.

What about fish oil supplements?

Fish oil supplements are readily available and can be helpful for people who find it challenging to consume enough marine sourced omega-3s from their diets.  In this case, two 1000mg fish oil capsules per day (providing 600mg marine triglycerides) will be ample for most people, unless you have a condition that is known to benefit from an increased dosage such as diabetes, arthritis, heart disease, high cholesterol and others  – check with your health professional if this is the case.  The odourless varieties have been safely encapsulated to allow digestion without the fishy aftertaste.  If you have a fish allergy, ensure you seek medical advice to avoid possible reaction.

It is advisable to include a 250mg dose of Vitamin E with fish oil supplements to provide antioxidant stabilisation for the omega-3s as they make their way to your cells.  Additionally, ensure the fish oils you use are protected from heat and light (store them in the fridge) to avoid losing potency due to oxidation.

In terms of brands, most reputable brands will contain similar ingredients.  Some brands such as Blackmores make different types with qualities aimed at specific health conditions (like cardiac and brain health) but really they’re all quite similar. Ask your APD if you’re still unsure. 

The NHMRC recommends an upper level of omega-3s of 3000mg for children, adolescents and adults as there is some evidence to suggest that high levels of these fatty acids may impair immune response and prolong bleeding time.  Therefore medical advice is recommended for condition specific larger doses. (Note: It is unlikely that this level of intake would be reached by consumption of seafood alone. If it were, then consideration would need to be given to the possible effects of concomitant intakes of other potential toxins such as mercury.)

People with high blood triglycerides and other medical conditions should take advice from their GP or APD before choosing fish oil supplements and omega-3 enriched foods and drinks as an alternative to drug therapy.

Check out Part 2 next week for info on fish vs krill oil, wild or farmed, mercury levels and that ever-so-hot word right now called 'sustainability'...