Omega-3 fatty acids are fats your body needs but cannot make on its own, so they must come from food or supplements. The three main types are ALA (from plants), and EPA and DHA (mainly from fish and algae), and they play somewhat different roles in the body.
There is no official Health Canada reference amount for EPA and DHA together, only an adequate intake for ALA. This article explains what each form does, how much ALA is recommended, and how to think about EPA and DHA if you choose a supplement.
What are ALA, EPA and DHA?
ALA (alpha-linolenic acid) is a plant-based omega-3 found in flaxseed, chia seeds, walnuts and canola oil. Your body can convert a small amount of ALA into EPA and DHA, but this conversion is limited and inefficient.
EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are the omega-3s found in fatty fish like salmon, sardines and mackerel, as well as in algae. DHA is a structural component of the brain and eyes, while EPA is involved in the body's normal inflammatory response.
Because your body converts so little ALA into EPA and DHA, getting these two directly from fish, algae oil or a fish oil supplement is the more reliable way to raise your levels.
How much ALA do you need?
Health Canada has set an adequate intake (AI) for ALA of 1.6 grams per day for men and 1.1 grams per day for women. This amount is achievable through food for most people who include some nuts, seeds or plant oils in their diet.
There is currently no established reference amount, or upper limit, for EPA and DHA specifically. This is why you will see a wide range of amounts on different fish oil or algae oil products, rather than one standard number.
- One tablespoon of ground flaxseed or a small handful of walnuts can help meet the daily ALA target.
- Canola oil and soybean oil also contribute smaller amounts of ALA to the diet.
- Since there is no UL for ALA, focus on getting a consistent amount from food rather than very high single doses.
Comparing the three omega-3 types
Each type of omega-3 comes from different sources and serves a somewhat different purpose in the body. The table below summarizes the basics.
| Type | Main sources | Main role |
|---|---|---|
| ALA | Flaxseed, chia, walnuts, canola oil | Plant-based omega-3; partly converted to EPA/DHA |
| EPA | Fatty fish, fish oil, some algae oil | Supports normal inflammatory balance |
| DHA | Fatty fish, fish oil, algae oil | Structural fat in the brain and eyes |
Food sources versus supplements
Fatty fish such as salmon, herring, sardines, trout and mackerel are the richest natural sources of EPA and DHA. Canada's Food Guide encourages including fish as a protein choice a few times a week, partly for this reason.
For people who do not eat fish regularly, whether by preference, allergy or diet (such as vegans and vegetarians), a supplement can help fill the gap. Algae-based oil provides EPA and DHA without using fish, while fish oil and krill oil are other common supplement forms.
We compare these supplement forms in more detail, including how they differ in absorption and other practical considerations, in a separate article on fish oil versus krill oil versus algae oil.
Choosing an amount that fits you
Because there is no set daily target for EPA and DHA, the right amount often depends on your diet, age and health goals, which is a conversation worth having with a pharmacist or doctor. Someone who eats fatty fish twice a week may need little to no supplement, while someone who rarely eats fish may benefit from a modest daily amount.
When choosing a product, look at the combined EPA plus DHA amount per serving rather than the total fish oil weight, since fish oil capsules also contain other fats. We explain how to interpret these numbers on a supplement label in a separate article dedicated to reading fish oil labels.
If you take blood thinners or have an upcoming surgery, mention any omega-3 supplement to your doctor or pharmacist, since higher amounts may have a mild effect on blood clotting.
- Check the EPA plus DHA amount per serving, not just the total oil weight.
- Consider your usual fish intake before choosing a supplement dose.
- Ask a pharmacist if you take blood thinners or other medications.
- Look for a Health Canada Natural Product Number (NPN) on licensed products.
Where omega-3s fit into overall heart health
Omega-3s are one piece of a broader picture that includes diet, physical activity, blood pressure and cholesterol management. They are not a replacement for prescribed heart medications or medical care.
We cover how omega-3s and other supplements fit alongside these broader heart health basics, and where their role is more limited, in a separate article on heart health and supplements.
The short version
- ALA is a plant omega-3 with a set Health Canada intake target; EPA and DHA come mainly from fish and algae and have no official target amount.
- Your body converts very little ALA into EPA and DHA, so direct sources matter for those two.
- DHA supports brain and eye structure, while EPA supports normal inflammatory balance.
- Fatty fish a few times a week can meet most people's EPA and DHA needs; algae oil is a fish-free alternative.
- Check the combined EPA plus DHA amount on a supplement label, and ask a pharmacist if you take blood thinners.
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Frequently asked questions
Is fish oil the same as omega-3?
Fish oil is one source of omega-3 fats, specifically EPA and DHA. Omega-3 is the broader category that also includes ALA from plant foods.
Do I need a supplement if I already eat fish?
If you regularly eat fatty fish like salmon or sardines a few times a week, you may already be meeting your EPA and DHA needs through food alone. A supplement may help if fish is rarely part of your diet.
Can vegetarians and vegans get enough omega-3?
Plant foods like flaxseed and walnuts can help meet the ALA target, but they provide very little EPA or DHA directly. Algae-based oil is a plant-friendly way to get EPA and DHA without fish.
Is there an upper limit for omega-3 supplements?
There is no established upper limit for EPA and DHA, though very high amounts may affect blood clotting in some people. Anyone on blood thinners or with a bleeding disorder should check with a doctor or pharmacist before starting a supplement.
Keep reading
- Fish Oil vs Krill Oil vs Algae Oil: How to Choose
- How to Read a Fish Oil Label: A Canadian Buyer's Guide
- CoQ10: Ubiquinone vs Ubiquinol Explained
- Heart Health Basics: Where Supplements Really Fit In
Sources
- NIH Office of Dietary Supplements: Omega-3 Fatty Acids
- Health Canada: Dietary Reference Intakes tables
- Health Canada: Reference values for elements (minerals)
This article is for general information only and is not medical advice. Talk to your doctor or pharmacist before starting a supplement, especially if you are pregnant or breastfeeding, take medication, or have a health condition.