The Three Omega-3 Fatty Acids: ALA, EPA, and DHA

Q: How Much Do You Need?

ALA: EFSA sets adequate intake at 0.5% of total energy, roughly 1.1 g/day for a 2,000 kcal diet. One tablespoon of ground flaxseed covers this. EPA + DHA combined: EFSA has approved health claims at 250 mg/day for heart and brain function (EFSA, 2010). Most health organizations suggest 250–500 mg combined EPA+DHA for general health. For specific conditions:

Q: Can I get enough EPA and DHA from plant foods alone?

Not from whole foods, no. ALA conversion to DHA is under 1% (Burdge & Calder, 2005). Algae-based supplements are the only reliable plant-based EPA+DHA source.

Q: Which omega-3 is best for the brain?

DHA. It is the dominant omega-3 in brain tissue and the one for which EFSA has approved a brain function claim at 250 mg/day (EFSA, 2010).

Q: Do I need to supplement all three?

You can get ALA easily from diet (flaxseed, walnuts). EPA and DHA are the ones most people need to supplement if they do not eat fatty fish regularly.

Q: Is omega-3 from fish better than from algae?

Functionally, no. Algae-derived EPA and DHA are chemically identical to fish-derived ones. Fish get their omega-3 from eating algae in the first place. The difference is ecological, not biochemical.

The Three Omega-3 Fatty Acids: ALA, EPA, and DHA Explained

When people say "omega-3," they usually mean one thing. In reality, there are three distinct fatty acids that fall under this umbrella, and they behave very differently in the body. Knowing the difference matters — especially when you are choosing a supplement or trying to understand why flaxseed oil is not a substitute for fish oil.

TL;DR

ALA (alpha-linolenic acid) comes from plants; EPA and DHA come primarily from marine sources
The body converts ALA to EPA and DHA at very low rates: ~5–10% for EPA, <1% for DHA (Burdge & Calder, 2005)
EPA is primarily anti-inflammatory; DHA is structural (brain and retina)
EFSA health claims require 250 mg combined EPA+DHA daily for heart and brain benefits
You cannot rely on ALA alone to cover your EPA/DHA needs
Algae-based supplements provide EPA+DHA without fish

ALA: The Plant-Based Omega-3

Alpha-linolenic acid (ALA) is an 18-carbon omega-3 fatty acid found in plant foods. It is the only omega-3 classified as "essential" — meaning your body cannot make it and must get it from food.

Best sources: flaxseed (22 g per 100 g), chia seeds (18 g per 100 g), hemp seeds (10 g per 100 g), walnuts (9 g per 100 g), canola oil (9 g per 100 g) (USDA, 2024).

ALA has its own modest health benefits. The Nurses' Health Study found that higher ALA intake was associated with a 40% lower risk of sudden cardiac death (Albert et al., 2005). However, ALA's primary limitation is its poor conversion to EPA and DHA.

The Conversion Problem

The conversion pathway goes: ALA → stearidonic acid → EPA → DPA → DHA. Each step is inefficient. In well-controlled tracer studies, conversion of ALA to EPA is roughly 5–10%, while conversion to DHA is less than 1% in men and somewhat higher (up to 9%) in young women, likely due to estrogenic influence (Burdge & Calder, 2005; Burdge et al., 2002).

This means eating 10 g of flaxseed oil (which provides ~5.5 g ALA) would yield approximately 275–550 mg EPA but only about 55 mg DHA at best. Not nothing, but nowhere near what a fish oil capsule provides.

EPA: The Anti-Inflammatory Omega-3

Eicosapentaenoic acid (EPA) is a 20-carbon omega-3 found primarily in fatty fish, shellfish, and algae. Its main roles are in inflammatory signaling and cardiovascular health.

How EPA works: EPA competes with arachidonic acid (an omega-6) for the same enzymatic pathways. When EPA is incorporated into cell membranes, the body produces less pro-inflammatory eicosanoids and more anti-inflammatory resolvins (Calder, 2013). This is the biochemical basis for omega-3's anti-inflammatory reputation.

Cardiovascular evidence: The REDUCE-IT trial (Bhatt et al., 2019) tested 4 g/day of icosapent ethyl (purified EPA) in patients with elevated triglycerides and found a 25% reduction in cardiovascular events. This was a higher dose than typical supplementation, but it demonstrated EPA's specific cardiovascular role.

Joint and muscle recovery: EPA may help manage exercise-induced inflammation. A meta-analysis by Li et al. (2022) found that omega-3 supplementation reduced delayed-onset muscle soreness (DOMS), though optimal EPA-specific doses are not firmly established.

DHA: The Structural Omega-3

Docosahexaenoic acid (DHA) is a 22-carbon omega-3 found in fatty fish, fish oil, and algae. Unlike EPA, DHA's primary role is structural — it is physically built into cell membranes.

Brain: DHA constitutes approximately 40% of the polyunsaturated fatty acids in the brain (McNamara & Carlson, 2006). It increases membrane fluidity, which affects the function of embedded receptors and ion channels.

Retina: The photoreceptor outer segments of the retina contain ~50–60% DHA in their phospholipids, making the eye one of the most DHA-rich tissues in the body (SanGiovanni & Chew, 2005).

Pregnancy: DHA accumulates rapidly in the fetal brain during the third trimester. EFSA recommends 200 mg additional DHA/day during pregnancy and lactation (EFSA, 2012).

Side-by-Side Comparison

Feature	ALA	EPA	DHA
Carbon chain	18	20	22
Primary sources	Flaxseed, chia, walnuts	Fatty fish, algae	Fatty fish, algae
Main role	Essential FA, energy	Anti-inflammatory signaling	Structural (brain, retina)
EFSA heart claim	No	Yes (250 mg with DHA)	Yes (250 mg with EPA)
EFSA brain claim	No	No	Yes (250 mg/day)
Adequate intake (EFSA)	0.5% of energy (~1.1 g)	No separate AI	No separate AI
Conversion from ALA	—	5–10%	<1%
Vegan-friendly source	Whole foods	Algae supplements	Algae supplements

How Much Do You Need?

ALA: EFSA sets adequate intake at 0.5% of total energy, roughly 1.1 g/day for a 2,000 kcal diet. One tablespoon of ground flaxseed covers this.

EPA + DHA combined: EFSA has approved health claims at 250 mg/day for heart and brain function (EFSA, 2010). Most health organizations suggest 250–500 mg combined EPA+DHA for general health. For specific conditions:

Goal	Suggested EPA+DHA	Notes
General health	250–500 mg/day	EFSA, WHO ranges
Athletic recovery	2–3 g/day	Higher EPA ratio may help (Jouris et al., 2011)
Pregnancy	450+ mg DHA/day	EFSA extra 200 mg DHA (EFSA, 2012)
High triglycerides	2–4 g/day	Clinical supervision needed (Skulas-Ray et al., 2019)

Common Mistakes

1. Thinking flaxseed replaces fish oil. Flaxseed is an excellent ALA source, but it does not meaningfully raise DHA levels. If you avoid fish, use algae-based EPA+DHA supplements.
2. Ignoring the EPA:DHA ratio. If your goal is joint inflammation, lean toward EPA-heavy products. For cognitive or eye support, choose DHA-dominant formulas.
3. Buying based on total omega-3 without checking the breakdown. A "1200 mg omega-3" supplement might contain 400 mg ALA and only 400 mg EPA+DHA.
4. Overlooking algae supplements. They provide both EPA and DHA without concerns about heavy metals or overfishing, and EFSA makes no distinction between fish-derived and algae-derived omega-3.

Estonia-Specific Notes

Estonian supermarkets stock a good variety of flaxseed, chia seeds, and walnuts for ALA. For EPA+DHA, Baltic herring (räim) and sprats (kilu) are affordable local options that provide both fatty acids — a 100 g serving of herring delivers roughly 700–1,100 mg DHA and 300–700 mg EPA.

If fish is not your preference, concentrated omega-3 and algae-based supplements are available at MaxFit.ee, with clear EPA and DHA breakdowns on product pages.

FAQ

Can I get enough EPA and DHA from plant foods alone?

Not from whole foods, no. ALA conversion to DHA is under 1% (Burdge & Calder, 2005). Algae-based supplements are the only reliable plant-based EPA+DHA source.

Which omega-3 is best for the brain?

DHA. It is the dominant omega-3 in brain tissue and the one for which EFSA has approved a brain function claim at 250 mg/day (EFSA, 2010).

Do I need to supplement all three?