The Omega-3 Problem on Plant-Based Diets
Omega-3 deficiency is near-universal in vegans and very common in vegetarians. The long-chain EPA and DHA — the forms your brain and body actually use — are found almost exclusively in marine sources.
ALA (alpha-linolenic acid), the short-chain omega-3 found in flaxseed, walnuts, and chia seeds, converts to EPA and DHA in the body. But this conversion is notoriously inefficient: only ~5–10% of ALA converts to EPA, and less than 1% converts to DHA.
Where Fish Really Get Their Omega-3
Here's the key insight: fish don't synthesize EPA and DHA. They get them by eating microalgae and other marine organisms. The fatty acids bioaccumulate up the food chain.
This means you can go directly to the source — algae — and skip the fish entirely. Algae oil provides direct EPA and DHA without the concerns about mercury, PCBs, overfishing, or the fish smell.
EPA vs DHA: What's the Difference?
EPA (Eicosapentaenoic Acid):
- Primary anti-inflammatory omega-3
- Mood and mental health (strongest evidence for depression)
- Cardiovascular protection
- Optimal dose: 500–1,000 mg/day
DHA (Docosahexaenoic Acid):
- Primary structural omega-3 in the brain (~97% of omega-3 in the brain is DHA)
- Critical for infant brain development and adult cognitive function
- Eye health (concentrated in the retina)
- Optimal dose: 250–500 mg/day
Most authorities recommend a combined EPA+DHA intake of 500–1,000 mg/day for general health.
Choosing an Algae Oil Supplement
When evaluating algae oil supplements, look for:
1. Total EPA+DHA content per serving — aim for ≥500 mg combined
2. Form: Triglyceride form is better absorbed than ethyl ester
3. Third-party testing: Look for IFOS or similar certification
4. Freshness: Omega-3s oxidize easily. Check the oxidation markers (TOTOX score)
5. No filler oils: Some supplements dilute with cheap vegetable oils
Fish Oil vs Algae Oil
Both provide bioavailable EPA and DHA. The choice often comes down to:
| Factor | Fish Oil | Algae Oil |
|---|---|---|
| EPA+DHA content | High | Moderate–High |
| Sustainability | Variable | More sustainable |
| Mercury/PCBs | Small risk (quality-dependent) | None |
| Suitable for vegans | No | Yes |
| Fish odor/burps | Common | Minimal |
For vegans and vegetarians, algae oil is the obvious choice. For omnivores, high-quality fish oil is also excellent.
Evidence Grade: A
EPA and DHA have some of the most extensive evidence in nutritional science. A 2019 meta-analysis of 13 RCTs (PMID: 30674433) confirmed cardiovascular benefits and supports cognitive health across the lifespan.