Fish Oil vs Algal Oil
Fish oil and algal oil compared for EPA and DHA: what blood-level trials show, which results come from company-linked studies, and why health outcomes have not been compared head to head.
Content last updated . This page has not been medically reviewed.
The question
Does algal (microalgae) oil give you the same omega-3 fats as fish oil? In blood-level trials, algal oil delivered DHA about as well as the fish-based sources it was compared with. Whether the two give the same health results has not been tested head to head in the sources we read. There is no universal winner, and this page does not tell anyone what to buy.What each option is
Fish oil supplements contain EPA and DHA. Algal oils are a vegetarian source of DHA, and some also contain EPA. [1] For product profiles, see Fish oil and Algal oil. For the fats themselves, see ALA, EPA and DHA.Documented differences and head-to-head evidence
| Question | What the source found | Strength of evidence |
|---|---|---|
| Does algal DHA reach the blood like fish DHA? | In 32 healthy adults aged 20 to 65, 600 mg a day of DHA as algal-oil capsules and as cooked salmon were bioequivalent in providing DHA to plasma and red blood cells. [2] | Small trial; salmon, not fish-oil capsules, was the comparator |
| Do different algal oils differ? | Two algal oil capsules at 200, 600 and 1,000 mg DHA a day gave equivalent DHA in plasma phospholipids and red cells in a 28-day trial. [3] | Biomarker; DHA-only oils |
| Direct comparison with fish oil capsules | In 74 adults, plasma phospholipid DHA and EPA from microalgal oil were statistically non-inferior to fish oil after 6 and 14 weeks. [4] | Randomized trial; several authors employed by dsm-firmenich |
| Heart, brain, eye or pregnancy outcomes | Proper evidence not found. We searched PubMed for trials comparing algal with fish oil on these outcomes and found none in the sources we read. | Insufficient evidence |
Reading the table carefully
- Blood level is a marker. Equal DHA in the blood does not by itself prove equal benefit.
- Industry involvement. The 2025 fish-versus-algal trial states that some authors are employed by dsm-firmenich. [4]
- EPA varies. The older trials tested DHA-only oils. [3] Algal oils differ on EPA. [1] See How to read a fish oil label.
- Cod liver oil is different. Fish liver oil supplements also contain vitamins A and D, which can be harmful in excessive amounts. [1]
No universal winner
Both raise blood DHA in the trials. Algal oil is a non-fish option, relevant to Supplements in vegetarian and vegan diets. Compare EPA and DHA per serving, not the oil total.Frequently asked questions
Is algal oil as good as fish oil?
For raising blood DHA and EPA, one trial found it non-inferior to fish oil, though some authors work for the algal oil maker. [4] Outcome trials comparing the two were not found.
Does algal oil contain EPA?
Some do and some are DHA-only. [1]
Is algal oil a vegetarian source?
NCCIH describes algal oils as a vegetarian source of DHA. [1]
Is algal oil safe?
In a 28-day trial in healthy adults, adverse event monitoring showed a good safety profile. [3] Ask a clinician if you take blood thinners or other medicines.
Do the studies show equal heart or brain benefits?
Proper evidence not found. The trials measured blood levels.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: evidence in adequately nourished people, promising but limited, insufficient evidence.
Safety and who should ask a clinician
- Side effects of omega-3 supplements are usually mild, such as taste, bad breath, heartburn, nausea or diarrhea. [1]
- The algal-oil trial reported an excellent safety and tolerability profile in healthy adults. [3] That does not cover people with health conditions.
- People who take blood thinners or other medicines, are pregnant or breastfeeding, have kidney or liver conditions, or face surgery should ask a clinician or pharmacist first. See Omega-3 safety and interactions and How interactions work.
- NHS notes that fish allergies are quite common and can cause severe reactions. [5] Whether algal oil suits a person with fish allergy is a question for an allergist; the sources we read did not address it.
- Quality varies: Quality testing and certifications.
References
- NCCIH. Omega-3 Supplements: What You Need To Know. US, last updated November 2024. Read 2026-10-22.
- Arterburn LM, et al. J Am Diet Assoc 2008. Algal-oil capsules and cooked salmon: nutritionally equivalent sources of docosahexaenoic acid. Read 2026-10-22.
- Arterburn LM, et al. Lipids 2007. Bioequivalence of Docosahexaenoic acid from different algal oils in capsules and in a DHA-fortified food. Read 2026-10-22.
- Bailey E, et al. Int J Mol Sci 2025. Comparative Bioavailability of DHA and EPA from Microalgal and Fish Oil in Adults. Read 2026-10-22.
- NHS. Fish and shellfish in your diet. UK. Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.