Omega-3 & Essential Fatty Acids: What to Know Before You Buy

Omega-3 supplements can look similar at first glance, but the amount and type of fatty acids they provide can vary considerably.

Some products use fish oil, while others use algal oil, flaxseed oil, cod liver oil or combinations of different oils. Labels may list ALA, EPA, DHA or total omega-3, and the amount of oil in a capsule is not necessarily the same as the amount of EPA and DHA it provides.

This guide explains the main types of essential fatty acids, how common omega-3 supplements differ, what to look for on the label and how to make a more meaningful comparison before choosing a product.

What Are Essential Fatty Acids?

Fatty acids are components of dietary fats. Some can be made by the body, while others need to come from the diet.

The two main fatty acids regarded as essential are:

  • alpha-linolenic acid (ALA) — an omega-3 fatty acid
  • linoleic acid (LA) — an omega-6 fatty acid

These essential fats are found naturally in foods including seeds, nuts, plant oils and other foods containing polyunsaturated fats.

Australian Nutrient Reference Values provide intake guidance for essential fatty acids according to age, sex and life stage. This means fatty acids should be considered as part of overall dietary intake rather than as nutrients that automatically require supplementation.

Omega-3 vs Omega-6

Omega-3 and omega-6 are both families of polyunsaturated fatty acids.

Omega-6 fats are widely available in foods including many nuts, seeds and vegetable oils. Omega-3 fats can come from both plant and marine sources.

When shopping for supplements, omega-3 tends to receive more attention because products can provide very different forms and amounts of omega-3 fatty acids.

Do not assume that an oil supplement is automatically a meaningful source of omega-3. The detailed fatty acid information on the label is more useful than simply seeing the word “oil” on the front of the product.

Understanding ALA, EPA & DHA

The three omega-3 fatty acids most commonly discussed when comparing foods and supplements are ALA, EPA and DHA.

ALA — Alpha-Linolenic Acid

ALA is the essential plant-based omega-3 fatty acid. Food sources include flaxseed or linseed, chia seeds, walnuts and oils such as flaxseed, canola and soybean oil.

The body can convert some ALA into longer-chain omega-3 fatty acids, but this conversion is limited. A product providing ALA therefore should not automatically be treated as equivalent to one that directly provides EPA and DHA.

EPA — Eicosapentaenoic Acid

EPA is a long-chain omega-3 fatty acid commonly found in marine oils, including fish oil.

DHA — Docosahexaenoic Acid

DHA is another long-chain omega-3 found in fish, marine oils and some algae-derived supplements.

When comparing omega-3 supplements, check whether the product provides ALA, EPA, DHA or a combination rather than relying only on a front-label statement such as “omega-3”.

Salmon, chia seeds, flaxseeds, walnuts and unbranded omega-3 softgels representing marine and plant sources of essential fatty acids

Who Is This Guide For?

This guide may be useful if you:

  • are comparing omega-3 supplements for the first time
  • want to understand the difference between fish oil and plant-based omega-3
  • are confused by EPA and DHA amounts on supplement labels
  • want to compare standard and concentrated fish oils
  • are deciding between capsules and liquid oils
  • want to understand how cod liver oil differs from ordinary fish oil
  • eat little or no fish and are considering other omega-3 sources
  • want to compare cost per serve rather than bottle price alone
  • already use other supplements and want to check for ingredient overlap

This guide provides general purchasing information rather than personalised medical or nutrition advice.

Food First: Omega-3 Is Available Without Supplements

Omega-3 fatty acids occur naturally in a range of foods.

Marine sources of EPA and DHA include oily fish such as:

  • salmon
  • sardines
  • mackerel
  • herring
  • some tuna and other seafood

Plant sources of ALA include:

  • flaxseed or linseed
  • chia seeds
  • walnuts
  • flaxseed oil
  • canola oil
  • soybean oil

The Heart Foundation encourages obtaining omega fats primarily through a healthy eating pattern and recommends regular fish consumption for most Australians.

A supplement may be considered in some circumstances, including where dietary sources are limited, but it should be assessed alongside the rest of your diet rather than assumed to be necessary for everyone.

Common Types of Omega-3 Supplements

The source of an omega-3 supplement can significantly change the fatty acids it provides.

Fish Oil

Fish oil is one of the most common supplemental sources of EPA and DHA.

Products can differ substantially in concentration. Two capsules that contain the same total amount of fish oil may provide quite different amounts of EPA and DHA.

For this reason, compare the detailed fatty acid quantities rather than total fish oil weight alone.

Concentrated Fish Oil

Some products are formulated to provide more EPA and DHA within a smaller amount of total oil.

This may reduce the number of capsules needed to obtain the labelled quantity of EPA and DHA, but “high strength” or “concentrated” terminology should still be verified against the ingredient panel.

Algal Oil

Certain algae-derived oils provide DHA and, depending on the formulation, may also provide EPA.

Algal oil can be relevant for people looking for a non-fish source of preformed long-chain omega-3. Check the specific EPA and DHA quantities because formulations differ.

Flaxseed or Linseed Oil

Flaxseed oil is rich in ALA.

It should not be compared with fish oil simply by looking at total oil weight because ALA, EPA and DHA are different fatty acids.

If your aim is to compare products for EPA and DHA content, check whether the plant-based product actually lists EPA or DHA rather than assuming all omega-3 sources provide the same fatty acids.

Cod Liver Oil

Cod liver oil provides omega-3 fatty acids but can also naturally contain vitamins A and D.

This makes label checking particularly important. Compare:

  • EPA and DHA content
  • vitamin A content
  • vitamin D content
  • serving directions
  • warnings
  • other supplements that already provide vitamins A or D

Cod liver oil therefore should not automatically be treated as interchangeable with an ordinary fish oil supplement.

Combination Oils

Some products combine several oils or fatty-acid sources.

Check which individual fatty acids the product actually provides. A longer list of oils does not automatically mean a higher EPA or DHA content or make the formula more suitable for every customer.

Do Not Compare Fish Oil by Total Oil Weight Alone

This is one of the most important points when comparing omega-3 supplements.

A label may state a large amount of fish oil per capsule or serve. Within that oil, only part may be EPA and DHA.

For example, two products may each contain a similar amount of fish oil but provide different quantities of:

  • EPA
  • DHA
  • other omega-3 fatty acids
  • other fatty acids

When EPA and DHA are the nutrients you are trying to compare, look for their stated quantities on the detailed label.

The Vitamin & Mineral Supplement Label Guide also explains useful principles for comparing serving sizes, active ingredients, directions and warnings rather than relying only on front-label numbers.

Check EPA & DHA Per Serve

Once you know which fatty acids a product contains, check how much the labelled serve actually provides.

Do not assume that:

  • one capsule equals one daily serve
  • a larger capsule provides more EPA and DHA
  • a larger bottle provides more usable serves
  • the product with the highest total oil number has the highest omega-3 concentration

One product may require a single capsule while another may require two or more capsules to provide its labelled serving amount.

For a meaningful comparison, check:

  • EPA per serve
  • DHA per serve
  • other omega-3 fatty acids stated
  • number of capsules or teaspoons per serve
  • recommended frequency
  • number of usable serves in the container

Is a Higher EPA or DHA Amount Always Better?

No.

A higher number does not automatically make a supplement the best choice for every person.

Products may use different proportions of EPA and DHA and may be intended for different labelled uses. Appropriate intake can also depend on diet, health circumstances, medicines and advice from a healthcare professional.

Rather than choosing the highest number available, compare the product against your reason for considering supplementation and follow the current label directions.

Higher supplemental amounts used for particular medical purposes should be discussed with an appropriate healthcare professional rather than self-selected solely from the front of a supplement bottle.

Capsules vs Liquid Omega-3

Omega-3 supplements are commonly available as soft capsules or liquids.

Capsules

Capsules provide a pre-measured amount and can be convenient for regular use.

When comparing them, consider:

  • capsule size
  • number required per serve
  • EPA and DHA per capsule and per serve
  • number of serves in the bottle

Liquid Oils

Liquid oils may suit people who prefer not to swallow multiple capsules.

Check:

  • the quantity required per serve
  • EPA and DHA per measured serve where applicable
  • storage instructions
  • refrigeration requirements after opening where stated
  • use-by or expiry information

No format is automatically superior. Choose based on the actual fatty-acid content, labelled directions and practical suitability.

Check the Complete Ingredient List

Omega-3 products can contain ingredients in addition to the main oil.

Depending on the formulation, these may include:

  • vitamin E or other antioxidants used in the formulation
  • vitamins A or D in products such as cod liver oil
  • flavourings in liquid products
  • gelatine or other capsule ingredients
  • additional oils
  • other active ingredients

If you use several supplements, compare the labels together so you can identify duplicated nutrients or ingredients.

A more complex formula is not automatically better than a simpler one.

Check Allergens & Dietary Suitability

Source matters when choosing an omega-3 product.

Fish oil and other marine products may not be appropriate for someone with relevant allergies or for people avoiding animal-derived ingredients.

Capsule shells and other inactive ingredients can also affect dietary suitability.

Check the current package for:

  • allergen statements
  • fish or seafood ingredients
  • capsule-shell ingredients
  • vegetarian or vegan suitability where relevant
  • other dietary statements important to you

Do not rely on the product name alone.

Storage & Freshness Matter

Oil-based supplements should be stored according to their individual label directions.

Check:

  • recommended storage temperature
  • whether refrigeration is required after opening
  • instructions to protect the product from heat or light
  • expiry or use-by information
  • how quickly a liquid product should be used after opening

This can be particularly important for liquid oils that are repeatedly exposed to air after opening.

Always follow the storage directions for the specific product rather than assuming every omega-3 supplement should be stored in the same way.

Omega-3 Supplements & Side Effects

Omega-3 supplements can cause side effects in some people.

Reported effects can include:

  • unpleasant taste or aftertaste
  • bad breath
  • heartburn
  • nausea
  • gastrointestinal discomfort
  • diarrhoea

Tolerance can vary with the product, serving size and individual.

Follow the current directions rather than increasing the amount because another omega-3 product used different instructions.

Omega-3 Supplements & Medicines

Omega-3 supplements can interact with medicines or require additional consideration in some circumstances.

This is particularly important if you use anticoagulant or antiplatelet medicines, have a bleeding disorder, are preparing for a medical procedure or use higher supplemental amounts.

If you take prescription or regular medicines, ask your doctor or pharmacist whether an omega-3 supplement is appropriate for you.

Do not use a general buying guide as a substitute for individual advice about medicine interactions.

Pregnancy & Breastfeeding

Fatty acids are important nutrients during pregnancy and breastfeeding, but product choice and intake should be considered carefully during these life stages.

Check the complete supplement formula rather than looking only at its omega-3 content. This is especially relevant with products such as cod liver oil that may also provide vitamin A and vitamin D.

If you are pregnant, planning pregnancy or breastfeeding, seek appropriate healthcare advice before beginning a supplement and follow current product warnings.

Food Standards Australia New Zealand also provides specific advice about mercury and the types and quantities of fish that should be limited during pregnancy and for young children.

What About Fish Oil for High Triglycerides or Heart Disease?

Omega-3 supplements are sometimes discussed in the management of particular cardiovascular conditions, including elevated triglycerides.

That is different from choosing a general nutritional supplement for everyday use.

The Heart Foundation recommends discussing omega-3 supplementation with a doctor where existing heart disease, heart failure or high triglyceride levels are involved.

If you have a diagnosed cardiovascular condition or are considering a high-strength omega-3 product for a therapeutic purpose, seek professional advice rather than choosing a dose independently.

Compare Cost Per Useful Serve

Bottle price alone can be misleading.

A lower-priced product may require more capsules per serve, while a concentrated product may provide fewer capsules but more EPA and DHA in each one.

For a more useful comparison, look at:

  • purchase price
  • number of capsules or amount of liquid
  • serving size
  • number of serves per container
  • EPA per serve
  • DHA per serve
  • whether other nutrients or oils are included

If EPA and DHA are your main comparison points, cost per usable serve is generally more informative than cost per capsule.

How to Compare an Omega-3 Supplement Before You Buy

Before choosing a product, ask:

  • What is the source of the omega-3?
  • Does it provide ALA, EPA, DHA or a combination?
  • How much EPA does the labelled serve provide?
  • How much DHA does the labelled serve provide?
  • Am I looking at total oil weight or actual omega-3 content?
  • How many capsules or how much liquid make one serve?
  • How many usable serves are in the container?
  • Does it contain other vitamins, oils or active ingredients?
  • Does it contain anything already present in my other supplements?
  • Are there relevant allergen or dietary-suitability statements?
  • What storage instructions apply?
  • What directions and warnings are on the current label?
  • Could it interact with any medicines I take?
  • Am I comparing cost per useful serve rather than bottle price alone?

Explore Essential Fatty Acid Supplements

Browse the current Essential Fatty Acids range to compare available oils, omega-3 products, formats, ingredient panels, directions and warnings.

For related categories, you can also explore Brain & Memory or Heart Health products where relevant to your broader shopping needs.

Or return to Health & Wellness Guides for more practical supplement-comparison information.

Frequently Asked Questions

What is the difference between essential fatty acids and omega-3?

Essential fatty acids are fatty acids that need to come from the diet. ALA is the essential omega-3 fatty acid, while linoleic acid is the essential omega-6 fatty acid. EPA and DHA belong to the omega-3 family but are different from ALA.

What is the difference between ALA, EPA and DHA?

ALA is mainly found in plant foods and oils such as flaxseed, chia, walnuts and canola oil. EPA and DHA are long-chain omega-3 fatty acids commonly obtained from fish, marine oils and some algae-derived products. The body can convert some ALA to EPA and DHA, but the conversion is limited.

Is 1000 mg of fish oil the same as 1000 mg of omega-3?

Not necessarily. The total amount of fish oil in a capsule can be higher than the amount of EPA, DHA and other omega-3 fatty acids it contains. Check the detailed ingredient information for the actual EPA and DHA quantities.

Should I compare fish oil by EPA and DHA?

If your aim is to compare the long-chain omega-3 content of fish oil products, EPA and DHA are useful figures to check. Also compare serving size, number of capsules required, directions, warnings and total usable serves.

Is a high-strength fish oil automatically better?

No. “High strength” can indicate a more concentrated formulation, but suitability depends on the actual EPA and DHA provided, serving instructions, other ingredients and your individual circumstances. Check the detailed label rather than relying on the front-label description.

Is flaxseed oil the same as fish oil?

No. Flaxseed oil is primarily a source of the plant omega-3 ALA, while fish oil directly provides long-chain omega-3 fatty acids including EPA and DHA. They should not be treated as equivalent simply because both contain omega-3.

What is algal omega-3?

Algal oil is derived from algae and can provide DHA, with some formulations also providing EPA. It can be an option for people seeking a non-fish source of long-chain omega-3, but the fatty-acid content varies between products.

Is cod liver oil the same as regular fish oil?

No. Cod liver oil provides omega-3 fatty acids but can also contain vitamins A and D. Check those nutrients as well as EPA and DHA, particularly if you already use other vitamin-containing supplements.

Do I need an omega-3 supplement if I eat fish?

Not necessarily. Omega-3 can be obtained from food, and the Heart Foundation recommends food sources as the main approach for most people. Whether supplementation is useful depends on your dietary intake and individual circumstances.

Can omega-3 supplements interact with medicines?

Yes, interactions and additional precautions can apply, particularly with medicines that affect blood clotting. If you take prescription or regular medicines, ask your doctor or pharmacist before beginning an omega-3 supplement.

Can omega-3 supplements cause side effects?

They can. Reported effects include unpleasant taste, bad breath, heartburn, nausea and gastrointestinal discomfort. Follow the labelled amount and seek professional advice if you experience problems or have concerns.

Should I take a higher-dose omega-3 for high triglycerides?

Do not self-select a high supplemental amount to manage a diagnosed condition. The use of omega-3 for high triglycerides or other cardiovascular conditions should be discussed with an appropriate healthcare professional.

Further Information

For additional information about essential fatty acids, omega-3, dietary sources and supplement safety, refer to:

Important Information

This Guide is general educational and purchasing information only. It does not provide personalised medical, nutrition or treatment advice and should not be used to diagnose or manage a health condition.

Supplement needs vary according to diet, age, health status, medicines, pregnancy or breastfeeding and other individual circumstances. If you have a diagnosed medical condition, take prescription or regular medicines, are pregnant or breastfeeding, have a relevant allergy, are preparing for surgery or are considering higher supplemental amounts, seek advice from an appropriate healthcare professional.

Dietary supplements should not replace a varied, balanced diet. Follow the directions and warnings on the specific product you purchase.

Product formulas, directions and warnings can change. Always check the current product label before purchase and use.