Omega-3, DHA & EPA Explained: Fish Oil vs Krill Oil

You may have seen terms such as “omega-3,” “DHA,” “EPA,” and “fish oil” on food labels or supplement packaging.

DHA and EPA are well known as fatty acids found in fish, but it is not always clear how they relate to omega-3s or how getting these nutrients from food differs from taking a fish oil supplement.

There are also several types of marine-derived oil supplements, including fish oil, krill oil and shark liver oil. Although they may appear similar, their sources and key components can be quite different.

In this article, we explain the basics of omega-3 fatty acids, the differences between DHA, EPA and ALA, common food sources, how fish oil, krill oil and shark liver oil differ, and what to look for when reading supplement labels.

What Are Omega-3 Fatty Acids?

Omega-3 fatty acids, also known as n-3 fatty acids, are a group of polyunsaturated fatty acids.

Some of the best-known omega-3 fatty acids are:

• ALA (alpha-linolenic acid)
• EPA (eicosapentaenoic acid)
• DHA (docosahexaenoic acid)

Although all three belong to the omega-3 family, they are not the same fatty acid.

ALA is found mainly in plant-based foods, while EPA and DHA are commonly associated with fish and other seafood.

Dietary fat is sometimes viewed as something that should simply be avoided. However, fat is an essential macronutrient that provides energy and contributes to important structures in the body, including cell membranes.

Rather than trying to eliminate dietary fat altogether, it is important to consider the types and amounts of fat consumed as part of an overall balanced diet.

What Is DHA?

DHA stands for docosahexaenoic acid and is a type of omega-3 fatty acid.

It is found in a variety of fish and seafood, including oily fish such as mackerel, sardines and other commonly eaten species.

DHA is also naturally present in the human body and forms part of the lipids found in cell membranes. It is present in tissues including the brain and retina and has been widely studied in nutrition and other scientific fields.

However, the presence of DHA in the body or research involving DHA should not be interpreted to mean that consuming a DHA-containing food or supplement will prevent or treat a particular disease.

When considering health and nutrition, it is important to look beyond a single nutrient and consider the overall diet together with factors such as physical activity, sleep and other lifestyle habits.

What Is EPA?

EPA stands for eicosapentaenoic acid. Like DHA, it belongs to the omega-3 family of fatty acids.

EPA is found in fish and seafood and is often present alongside DHA.

EPA has been investigated in many areas of nutrition and health research. However, studies may differ considerably in the form of EPA used, the amount provided, the people studied and the duration of the research.

It is also important to distinguish between dietary supplements and medicines.

In some countries, pharmaceutical products containing EPA or related omega-3 ingredients may be prescribed or otherwise used for specific medical purposes. These medicines should not be considered equivalent to general fish oil supplements sold as foods or dietary supplements.

If you have been advised that you have elevated triglycerides, cholesterol, blood pressure or another health concern, do not rely on a supplement as a substitute for appropriate medical care. Speak with a qualified healthcare professional for individual advice.

What Is the Difference Between DHA and EPA?

DHA and EPA are both omega-3 fatty acids commonly found in fish, but they differ in their chemical structures, distribution within the body and metabolism.

In an ordinary diet, however, DHA and EPA are not necessarily consumed separately.

Many fish contain both DHA and EPA, and many fish oil and krill oil supplements also provide a combination of the two.

For this reason, when comparing supplements it is useful to look beyond a large number such as “Fish Oil 1000 mg” on the front of the package and check how much EPA and DHA the product actually provides.

ALA Is Also an Omega-3 Fatty Acid

Omega-3 is sometimes used as though it simply means DHA and EPA, but ALA, or alpha-linolenic acid, is also an omega-3 fatty acid.

Foods that can provide ALA include:

• Perilla oil
• Flaxseed oil
• Walnuts
• Seeds such as chia seeds

The human body can convert some ALA into EPA and subsequently DHA, but this conversion is limited.

Therefore, although ALA, EPA and DHA all belong to the omega-3 family, plant-derived ALA should not be regarded as identical to EPA and DHA obtained from fish and seafood.

Which Foods Contain Omega-3 Fatty Acids?

EPA and DHA are found in fish and seafood, with oily fish being particularly well-known sources.

The actual amounts can vary according to the species, part of the fish, season, whether it is wild or farmed, and other factors.

ALA, meanwhile, can be obtained from plant-based foods such as perilla oil, flaxseed oil and walnuts.

This means there are different dietary sources of omega-3 fatty acids: fish and seafood can provide EPA and DHA, while certain plant foods can provide ALA.

Fish also provides more than omega-3 fatty acids. Depending on the type of fish, it can contribute protein as well as various vitamins and minerals to the diet.

For this reason, it is better to consider omega-3 intake within the context of a varied and balanced diet rather than focusing on one isolated nutrient.

How Much Omega-3 Do Adults Need?

Recommended or suggested intakes for omega-3 fatty acids vary between countries and health authorities.

For example, Japan's Dietary Reference Intakes (2025 edition) provides age- and sex-specific adequate intake values for total n-3 fatty acids.

For adults aged 18 and over, these values are generally around:

• Men: approximately 2.2–2.3 g per day
• Women: approximately 1.7–2.0 g per day

Importantly, these figures refer to total n-3 fatty acids rather than EPA and DHA alone.

They include n-3 fatty acids such as ALA, EPA and DHA.

The Japanese Dietary Reference Intakes also considers research relating EPA and DHA to health outcomes. However, it does not establish a specific EPA/DHA target intake for the prevention of disease.

For this reason, claims such as “taking a certain amount of EPA and DHA will prevent a particular disease” should not be inferred from these reference values.

Dietary recommendations also vary internationally, so readers outside Japan should refer to guidance from the relevant health authority in their own country.

Reference: Ministry of Health, Labour and Welfare, Japan — Dietary Reference Intakes for Japanese

Is Eating Fish the Same as Taking a Fish Oil Supplement?

Eating fish and taking a fish oil supplement can both provide EPA and DHA, but they are not the same thing.

Fish provides more than EPA and DHA. It is also a source of protein and, depending on the type of fish, various vitamins and minerals.

Fish oil supplements, on the other hand, contain oil derived from fish and are generally provided in capsules or other convenient forms. They are designed to provide components of fish oil, including EPA and DHA.

For this reason, fish oil supplements should not be considered a complete substitute for eating fish or other nutritious foods.

A varied and balanced diet should remain the foundation, with supplements considered as one possible way to complement the diet when appropriate.

What Is a Fish Oil Supplement?

Fish oil is oil obtained from fish.

Fish oil supplements commonly contain refined fish oil in softgel capsules and provide omega-3 fatty acids such as EPA and DHA.

However, not every fish oil supplement contains the same amount of EPA and DHA.

The composition can vary according to the source of the oil, its concentration and the way the product is formulated.

This is why it is important to check the detailed ingredient and nutrition information rather than relying only on the product name or capsule size.

Does “Fish Oil 1000 mg” Mean 1000 mg of EPA and DHA?

Not necessarily.

This is one of the most useful things to understand when comparing fish oil supplements.

If a product states “Fish Oil 1000 mg,” the 1000 mg may refer to the total amount of fish oil rather than the combined amount of EPA and DHA.

EPA and DHA make up part of the fatty-acid composition of the oil, so it is important to look further down the label and check how many milligrams of EPA and DHA are actually provided.

It is also useful to compare products based on the manufacturer's suggested daily intake rather than only the amount contained in a single capsule.

For example, one product may be designed to provide its stated daily amount in one capsule, while another may require two or more capsules.

5 Things to Check When Comparing Fish Oil Supplements

1. Check the EPA and DHA Content

Start by looking at the amount of EPA and DHA provided.

Rather than comparing only the total amount of fish oil shown prominently on the packaging, check the detailed label to see how much EPA and DHA the product actually contains.

2. Compare the Suggested Daily Intake

Suggested intake can vary considerably between products.

A comparison based only on one capsule may therefore be misleading.

Check how much of each component is provided by the suggested daily serving to better understand the differences between products.

3. Check the Source and Ingredients

It is also important to know what the supplement is made from.

If you have an allergy to fish, shellfish or other seafood, carefully check the ingredient and allergen information before using a marine-derived supplement.

4. Look Beyond EPA and DHA

Some marine oil supplements contain or highlight components other than EPA and DHA.

For example, krill oil products may contain phospholipids and naturally occurring astaxanthin, while some shark liver oil supplements are formulated around squalene.

Products described as marine oils should therefore not automatically be considered interchangeable.

5. Follow the Suggested Intake

More is not necessarily better when it comes to supplements.

Follow the suggested intake and directions provided on the product label, and take particular care when using several supplements containing similar ingredients.

Fish Oil vs Krill Oil vs Shark Liver Oil: What's the Difference?

When comparing marine oil supplements, you may come across fish oil, krill oil and shark liver oil.

Although all three are derived from marine sources, their sources and characteristic components are different.

Rather than asking which type is universally “best,” it is more useful to understand what each product contains and how it is formulated.

Fish Oil: A Source of EPA and DHA

Fish oil is obtained from fish and commonly contains the omega-3 fatty acids EPA and DHA.

The amount and proportion of EPA and DHA can vary considerably between products.

For example, Health Life Super Atlantic Fish Oil provides the following amounts per capsule:

• EPA: 410 mg
• DHA: 312 mg
• EPA + DHA: 722 mg in total
• Suggested intake: 1 capsule daily

This is a good example of why the total amount of “fish oil” alone does not provide all the information needed to compare products.

Looking at the individual EPA and DHA amounts gives a clearer picture of the product's composition.

Krill Oil: Oil Derived from Krill

Krill oil is obtained from krill, small crustaceans found in the ocean.

Like fish oil, krill oil can provide EPA and DHA. One characteristic of krill oil is that it also contains phospholipids.

Krill oil naturally contains astaxanthin as well, although the amount varies between products.

Health Life Antarctic Krill Oil provides the following amounts per suggested daily serving of 2 capsules:

• Krill oil: 1,000 mg
• Total omega-3 fatty acids: 380 mg
• EPA: 210 mg
• DHA: 100 mg
• Phospholipids: 560 mg
• Choline: 70 mg
• Astaxanthin: 85 μg

The suggested intake is 2 capsules daily.

This illustrates why fish oil and krill oil should not be compared only by the total weight of the oil. The EPA and DHA content, other naturally occurring components and suggested daily serving should all be considered when reading the label.

Shark Liver Oil: A Source of Squalene

Shark liver oil is obtained from the liver of sharks.

Although both shark liver oil and conventional fish oil are marine-derived oils, they should not be considered the same type of supplement.

Some shark liver oil supplements are formulated around squalene rather than EPA and DHA.

For example, Health Life Squalene provides the following amounts per capsule:

• Squalene: 500 mg
• Vitamin E: 5 mg
• Suggested intake: 1 capsule daily

Its composition is therefore different from a conventional fish oil supplement designed primarily around EPA and DHA.

Rather than assuming that “shark liver oil” means “omega-3 supplement,” check which components are actually listed on the individual product label.

Fish Oil, Krill Oil and Shark Liver Oil at a Glance

As this comparison shows, marine oil supplements can differ substantially even when they appear similar at first glance.

When comparing products, check the source, specific components, amount provided per suggested daily serving and directions for use.

Are Squalene and Squalane the Same Thing?

When researching shark liver oil, you may encounter two very similar terms: “squalene” and “squalane.”

They are related, but they are not the same substance.

Squalene is a naturally occurring lipid found in a variety of organisms, including humans. In the human body, it is also an intermediate in the pathway used to produce cholesterol and other sterol compounds.

Squalane, on the other hand, is the hydrogenated form of squalene. Hydrogenation makes it more chemically stable, which is one reason squalane is commonly used as an ingredient in skincare and cosmetic products.

The names differ by only one letter, but squalene and squalane are not chemically identical.

Squalene is also sometimes described in promotional material as an “oxygen carrier.”

This description should not be interpreted to mean that consuming squalene as a food or supplement transports oxygen around the human body, corrects low oxygen levels or treats health conditions.

When reading about squalene, it is important to distinguish between the chemical characteristics of the compound, laboratory research and what can reasonably be concluded about consuming it as a dietary supplement.

Can Omega-3 Supplements Replace Fish in Your Diet?

Fish oil and krill oil supplements can provide components such as EPA and DHA, but they should not be considered a replacement for fish or a varied diet.

Fish provides more than omega-3 fatty acids. It can also contribute protein, vitamins and minerals as part of an overall balanced diet.

For this reason, food should remain the foundation of your diet, while supplements can be considered a way to complement your everyday nutritional intake when appropriate.

Taking more supplements simply because you do not eat much fish is not necessarily the best approach.

Consider your overall eating habits first, then decide whether a supplement may be appropriate for your individual needs.

Omega-3 Supplements and Omega-3 Medicines Are Not the Same

When researching EPA and DHA, you may come across information relating omega-3 fatty acids to triglycerides and other health topics.

It is important to understand that general fish oil supplements and omega-3 products used as medicines are not the same thing.

Medicines contain specified active ingredients and doses and are authorised for particular medical uses. Depending on the country and product, they may be prescribed or used under the supervision of healthcare professionals.

Fish oil and krill oil supplements sold as foods or dietary supplements have a different regulatory status and should not be treated as substitutes for prescribed medicines.

If a medical check-up has identified concerns relating to triglycerides, cholesterol, blood pressure or other health measurements, do not replace medical treatment with a supplement without professional advice.

Speak with a doctor or other qualified healthcare professional if you have questions about your test results or health condition.

What Should You Consider Before Taking a Supplement?

Although dietary supplements are not medicines, this does not mean that any amount is appropriate for everyone.

Your individual health circumstances, the amount consumed, medicines you take and other supplements you use may all need to be considered.

Follow the Suggested Intake

Always check the suggested intake and directions provided on the product label.

Taking a larger amount of a nutrient or supplement does not necessarily provide greater benefits.

If you use more than one omega-3 or marine oil supplement, check the ingredient lists and amounts carefully to avoid unintentionally duplicating ingredients.

If You Take Medicines

Some supplements may require additional consideration when used alongside medicines.

If you regularly take prescription medicines, are receiving medical treatment or have an existing health condition, speak with your doctor or pharmacist before starting a new supplement.

During Pregnancy or Breastfeeding

Nutritional requirements and considerations can change during pregnancy and breastfeeding.

If you are pregnant or breastfeeding, check the product information carefully and seek individual advice from an appropriate healthcare professional when necessary rather than increasing supplement intake on your own.

If You Have Fish or Shellfish Allergies

Fish oil is derived from fish, while krill oil is derived from krill, which are crustaceans.

If you have an allergy to fish, shellfish or other seafood, carefully check the ingredients and allergen information before using a marine-derived supplement.

If you are unsure whether a product is suitable for you, contact the manufacturer or retailer or seek advice from an appropriate healthcare professional.

Don't Choose an Omega-3 Supplement Based Only on “What It Does”

Online information about supplements sometimes includes statements claiming that a particular ingredient can “prevent,” “treat” or “improve” a specific health condition.

However, results from nutritional or scientific research cannot automatically be applied to every commercially available supplement.

Studies can differ in many ways, including the people studied, the amount and form of an ingredient used, the duration of the study and the research design.

Even when research has been conducted on a particular nutrient or compound, this does not mean that every product containing that ingredient will produce the same result.

Rather than choosing a supplement solely on the basis of health claims, look at practical information such as the source of the ingredients, the amount of each key component and the suggested daily intake.

Frequently Asked Questions

Are omega-3, DHA and EPA the same thing?

Not exactly.

Omega-3 refers to a family of fatty acids. DHA and EPA are two members of this family, along with ALA (alpha-linolenic acid) and other omega-3 fatty acids.

Are DHA and EPA found only in fish?

DHA and EPA are particularly associated with fish and seafood.

Plant foods such as perilla oil, flaxseed oil, walnuts and certain seeds can provide ALA, another type of omega-3 fatty acid.

The human body can convert some ALA into EPA and subsequently DHA, although this conversion is limited.

Does Fish Oil 1000 mg mean 1000 mg of EPA and DHA?

Not necessarily.

“Fish Oil 1000 mg” may refer to the total amount of fish oil in a serving or capsule rather than the amount of EPA and DHA.

When comparing products, check the separately listed amounts of EPA and DHA as well as the suggested daily serving.

Are fish oil and krill oil the same?

No.

Fish oil is derived from fish and commonly provides EPA and DHA.

Krill oil is derived from krill and can provide EPA and DHA together with other components such as phospholipids and naturally occurring astaxanthin.

Rather than assuming that one is universally better than the other, compare the source, composition and amount provided by the suggested daily serving.

Is shark liver oil an omega-3 supplement?

Shark liver oil should not automatically be classified as an omega-3 supplement.

Some shark liver oil products are formulated around squalene as a characteristic component, while conventional fish oil products commonly focus on EPA and DHA.

Always check the ingredient and composition information for the individual product rather than relying on the general term “marine oil.”

Are squalene and squalane the same?

No.

Squalene is a naturally occurring lipid found in various organisms, including the human body.

Squalane is produced by hydrogenating squalene to create a more chemically stable compound and is commonly used in skincare and cosmetic formulations.

Can I take fish oil instead of eating fish?

Fish oil supplements should not be regarded as a complete substitute for eating fish.

Fish provides protein and various vitamins and minerals in addition to EPA and DHA.

A balanced diet should remain the foundation, with supplements used when appropriate to complement nutritional intake.

Is more EPA and DHA always better?

No.

A higher amount is not automatically better or more appropriate for every person.

Follow the suggested intake on the product label and be aware of overlapping ingredients if you use multiple supplements.

Summary: Look at the Ingredients, Not Just the Words “Omega-3”

Omega-3 fatty acids include DHA, EPA and ALA.

DHA and EPA are commonly found in fish and seafood, while ALA is found in plant foods such as perilla oil, flaxseed oil and walnuts.

Although they all belong to the omega-3 family, they are not identical fatty acids.

Fish oil, krill oil and shark liver oil are also different products:

• Fish oil: derived from fish and commonly provides EPA and DHA
• Krill oil: derived from krill and can provide EPA, DHA, phospholipids and other naturally occurring components
• Shark liver oil: derived from shark liver and may be formulated around squalene as a characteristic component

When comparing supplements, do not rely only on terms such as “omega-3” or “fish oil,” or on the largest number printed on the front of the package.

Instead, check the source, specific components such as EPA and DHA, the amount provided by the suggested daily serving and the directions for use.

Most importantly, supplements should not be the sole basis of your approach to nutrition and wellbeing.

A varied diet that includes nutritious foods, together with regular physical activity, adequate sleep and other everyday lifestyle habits, remains important.

If you choose to use a supplement, consider it a way to complement your everyday diet rather than a replacement for food or medical care.