Supplements › Fatty acid or lipid

DHA (docosahexaenoic acid)

DHA is an omega-3 fat from fish and algae that builds up in the brain and retina. Most studied for lowering triglycerides and for pregnancy and infant growth.

Strongest evidenceCholesterolStrong, 215 studies
Median dose in studies800 mg a dayFrom 633 study groups
Upper limitNone setEFSA: DHA alone up to about 1 g a day raises no safety concern.
Algal oil supplement100 to 300 mg of DHAThe usual amount in plant-based supplements. Some also contain EPA.
Ask a doctor or pharmacist first

Ask a doctor or pharmacist first if you:

  • take warfarin or a similar blood thinner: fish oil may prolong clotting times, and prescription omega-3 labels call for checks of INR, a clotting test[1]
  • have high LDL cholesterol: DHA raised LDL cholesterol in trials, while EPA did not[2]
  • have heart disease or a high risk of it: in such people, 4 g a day of omega-3 for several years slightly raised the risk of atrial fibrillation. This is an irregular heartbeat.[1]
  • are pregnant: omega-3 fats in pregnancy probably made pregnancies longer than 42 weeks more common, 2.6% against 1.6%[3]
  • have a baby born very early: a high dose of DHA in babies born before 29 weeks raised the risk of bronchopulmonary dysplasia, a lung disease[4]

Overview

What is DHA?

DHA (docosahexaenoic acid) is a long-chain omega-3 fat. It is part of the membranes of cells and is especially high in the retina, the brain and sperm.[1] Microalgae make DHA, and fish collect it through the food chain.[1]

Fatty fish are the richest foods: 3 ounces (about 85 g) of cooked farmed Atlantic salmon has 1.24 g of DHA.[1] Supplements that contain DHA include fish oil, krill oil, cod liver oil and algal oil, the vegetarian source.[1][5] Most infant formulas sold in the US have DHA added.[1]

What is DHA used for?

The best evidence is for blood fats and pregnancy. In 11 trials, DHA from algal oil lowered triglycerides by 0.20 mmol/L, but raised LDL cholesterol by 0.23 mmol/L.[6] The large heart trials described by the NIH tested EPA and DHA together, or EPA alone.[1]

In pregnancy, omega-3 fats lowered birth before 34 weeks by 42% in a Cochrane review.[3] A 2026 review of 19 trials found that DHA in pregnancy did not improve the child's brain development, but birth weight was 72.5 g higher.[7]

For memory, a review of 10 trials in 2,327 older adults found no clear effect.[8] Some markers of inflammation fell more with DHA than with EPA in one trial.[9]

Is DHA safe?

For most adults, yes, at the doses studied. EFSA found that DHA alone up to about 1 g a day raises no safety concern for the general population.[10] No upper limit has been set in the US or the EU.[1][10] Side effects of omega-3 supplements are usually mild: an unpleasant taste, bad breath, heartburn, nausea, diarrhea and headache.[1][5]

DHA raises LDL cholesterol a little: by 7.23 mg/dL against placebo in a review of trials.[2] People who take warfarin should ask a doctor or pharmacist first, because prescription omega-3 labels call for INR checks.[1] In babies born before 29 weeks, a high dose of DHA raised the risk of a lung disease.[4]

How it works

DHA (docosahexaenoic acid) is a long-chain omega-3 fat with 22 carbon atoms.[1] The body can make it from ALA, the omega-3 fat in plants, but reported conversion rates are below 15%.[1]

  1. Gut absorption

    Enzymes in the gut split the fat, and bile salts carry the pieces into the cells of the gut wall. About 95% is absorbed, as with other fats.[1]

  2. Transport

    Gut cells pack DHA into chylomicrons, fat particles that pass through the lymph into the blood. Lipoprotein particles then carry it to the organs.[1]

  3. Cell membranes

    DHA becomes part of the membranes of cells. Levels are especially high in the retina, the brain and sperm.[1] Before birth, DHA builds up fastest in the last 3 months of pregnancy. The retina has its full amount at birth, and the brain keeps adding DHA for the first 2 years.[1]

  4. Signal molecules

    Cells make signal molecules called eicosanoids from fats. DHA and EPA compete with arachidonic acid, an omega-6 fat, and this moves the balance toward less inflammatory activity.[1]

  5. Liver

    The liver breaks omega-3 fats down by beta-oxidation.[11] In the liver they also appear to slow the making of triglycerides and speed up their breakdown, but the exact mechanism is not clear.[11]

Benefits and studies

Each row is one benefit. The square shows the grade and the number of studies. Open a row to see the most trusted studies.

StrongModerateWeakNo trials
BenefitMain effects in studiesStudiesPeople

Dose

In 11 trials of algal oil, the median dose was 1.68 g of DHA a day.[6] Pregnancy trials gave 600 to 1000 mg a day.[12][13] The US has set no daily intake for DHA.[1]

Usual dose

For triglycerides, the median dose in 11 algal oil trials was 1.68 g a day, and the ComparED trial gave 2.7 g a day.[6][9] In pregnancy, trials gave 600 mg, 800 mg or 1000 mg a day.[12][14][13] Memory trials in older adults gave 900 mg to 2 g a day.[15][16]

Daily need

The US adequate intake covers only ALA, the plant omega-3: 1.6 g a day for men and 1.1 g for women.[1] EFSA, the EU food safety authority, advises 250 mg of EPA and DHA a day for adults, plus 100 to 200 mg of DHA in pregnancy.[1] The current advice for breastfeeding mothers is 250 to 375 mg of DHA and EPA a day.[17]

Form

Algal oil supplements, the plant-based source, usually give 100 to 300 mg of DHA, mostly as triglycerides.[1] A typical 1000 mg fish oil capsule gives about 120 mg of DHA and 180 mg of EPA.[1] In a 2-week trial, 600 mg of DHA a day from algal oil raised blood DHA as much as the same amount from cooked salmon.[18]

How long

Triglycerides fell within 10 weeks in the ComparED trial.[9] Pregnancy trials started before week 20 or 21 and lasted until birth.[12][14] Memory trials lasted from 24 weeks to 18 months.[15][19]

Upper limit

Neither the US nor the EU has set an upper limit.[1][10] EFSA found that DHA alone up to about 1 g a day raises no safety concern for the general population.[10] For adults, EPA and DHA together up to 5 g a day raise none either.[10] People who take a blood thinner should ask a doctor or pharmacist first.[1]

Doses in studies

Most studies gave 1,000 to 2,500 mg a day, for 1 to 3 months.

The counts are study groups. A study group is one set of people in a study who took the same dose. One study can have several groups. These are amounts from studies, not advice for you.

How much a day633 groups in 499 studies
  1. Up to 100 mg23 groups
  2. 100 to 250 mg81 groups
  3. 250 to 500 mg131 groups
  4. 500 to 1,000 mg167 groups
  5. 1,000 to 2,500 mg168 groups
  6. 2,500 to 5,000 mg55 groups
  7. 5,000 mg or more8 groups
For how long545 groups in 434 studies
  1. 1 week or less23 groups
  2. 1 to 4 weeks73 groups
  3. 1 to 3 months245 groups
  4. 3 to 6 months122 groups
  5. 6 to 12 months43 groups
  6. More than a year39 groups
Half of the groups took less than 800 mg a day. Half took more.Half of the groups took 375 to 1,500 mg a day. A quarter took less, a quarter took more.398 of 633 groups took 500 mg a day or more. Do not copy a study dose without a doctor.

Taken together

437 of 665 study groups took DHA (docosahexaenoic acid) with something else. This shows what studies gave together, not what works together.

  1. Omega-3 Fatty Acids194 studies244
  2. Fish Oil105 studies124
  3. eicosapentaenoic acid (EPA)50 studies56
  4. EPA34 studies42
  5. Eicosapentaenoic Acid31 studies36
  6. Arachidonic Acid24 studies27
  7. Vitamin E16 studies18
  8. Choline8 studies12
  9. Lutein11 studies12
  10. Folic Acid9 studies11
Bars and numbers count study groups. A companion is shown only when at least 3 different studies gave it.

Protocols

What studies used when they gave DHA (docosahexaenoic acid) for one goal, or to a group of people.

Each protocol describes what studies used, for one goal or for one group of people. It is not advice for you: talk to a doctor before you start a supplement.

Questions

12 questions in 4 groups. Open one for the short answer; each has its own page with the full answer and sources.

Basics
What is the difference between DHA and EPA?

Both are long-chain omega-3 fats from fish and algae: DHA has 22 carbon atoms and EPA has 20.[1] In trials that gave one or the other, both lowered triglycerides, but only DHA raised LDL and HDL cholesterol.[2] For depression, products with mostly EPA helped and products with mostly DHA did not.[20]

Read the full answer ›
Which foods are high in DHA?

Fatty fish. In 3 ounces (about 85 g) of cooked fish, farmed Atlantic salmon has 1.24 g of DHA and wild Atlantic salmon 1.22 g. Herring has 0.94 g, sardines canned in tomato sauce 0.74 g and Atlantic mackerel 0.59 g.[1] Light tuna canned in water has 0.17 g, and one cooked egg has 0.03 g.[1]

Flaxseed, chia seeds and walnuts have ALA, a plant omega-3, not DHA.[1] Some eggs, yogurts, milks and soy drinks have DHA added.[1] US adults get only about 90 mg of DHA and EPA a day from food.[1]

Open the answer with sources ›
Benefits
Does DHA lower triglycerides?

Yes. In a review of 11 trials with 485 healthy people, a median of 1.68 g of DHA a day from algal oil lowered triglycerides by 0.20 mmol/L.[6] It also raised LDL cholesterol by 0.23 mmol/L and HDL cholesterol by 0.07 mmol/L.[6] In trials that compared the two directly, DHA lowered triglycerides more than EPA.[2]

Read the full answer ›
Does DHA in pregnancy help the baby?

It may lower the risk of early preterm birth, but it has not improved the child's brain development. A 2026 review of 19 trials found no benefit of DHA in pregnancy for the child's attention, intelligence, language or memory, and birth weight was 72.5 g higher.[7] In a Cochrane review, omega-3 fats lowered birth before 34 weeks from 4.6% to 2.7%.[3]

Read the full answer ›
Does DHA improve memory?

In healthy older adults, probably not much. A review of 10 studies with 2,327 older adults found no clear effect of DHA on memory, attention or executive function.[8] Some single trials found gains, for example with 900 mg a day for 24 weeks.[15] In mild to moderate Alzheimer's disease, 2 g a day for 18 months did not slow decline.[19]

Read the full answer ›
Does infant formula with DHA help babies develop?

For babies born at term, a Cochrane review of 15 trials found no clear benefit on development and no consistent benefit on vision, with low-quality evidence.[21] Most formulas sold in the US contain DHA and arachidonic acid, but 2 Cochrane reviews found the evidence too weak to recommend these formulas.[1]

For babies born very early, results are mixed. In 1,273 babies born before 29 weeks, 60 mg of DHA per kg of body weight a day raised bronchopulmonary dysplasia, a lung disease, to 49.1% from 43.9%.[4] In 656 of these children tested at age 5, IQ was 3.45 points higher with DHA.[22] A 2025 review pooled 13 trials of long-chain fatty acids in preterm or low birth weight babies.[23] It found no clear effect on IQ, but possibly a lower risk of intellectual disability.[23]

Open the answer with sources ›
Does DHA help the eyes?

In older adults, trials found no benefit. In AREDS2, adding 350 mg of DHA and 650 mg of EPA to an eye vitamin formula did not slow age-related macular degeneration over 5 years.[1] In the DREAM trial, 1000 mg of DHA and 2000 mg of EPA a day for 12 months did not ease dry eye more than olive oil.[1]

In babies, results are mixed. A Cochrane review found better visual acuity at 12 months in 3 formula trials, but not in 3 others, with low-quality evidence.[21] In 206 babies born before 28 weeks, arachidonic acid with DHA halved severe retinopathy of prematurity, an eye disease of preterm babies: 15.8% against 33.3%.[24]

Open the answer with sources ›
Does DHA help with depression?

Not as DHA alone. A 2019 review of 26 trials with 2,160 people found that omega-3 products with at least 60% EPA eased symptoms of depression, while products with pure DHA or mostly DHA did not.[20] NCCIH says it is not certain that omega-3 supplements help depression, and that EPA may help more than DHA if they do.[5]

In the DOMInO trial, 800 mg of DHA a day in pregnancy did not lower depression after birth: 9.67% against 11.19%, a difference that was not significant.[14]

Open the answer with sources ›
Safety
Does DHA raise LDL cholesterol?

Yes, a little. In a review of placebo-controlled trials, DHA raised LDL cholesterol by 7.23 mg/dL, while EPA did not raise it.[2] In 11 trials of algal oil, the rise was 0.23 mmol/L, together with a rise in HDL cholesterol of 0.07 mmol/L.[6]

EFSA found that 2 to 4 g of DHA a day raises LDL cholesterol by about 3%, which may not change the risk of heart disease.[10] DHA also made LDL particles larger.[25] People with high LDL cholesterol should ask a doctor or pharmacist first.[2]

Open the answer with sources ›
Is DHA safe while breastfeeding?

LactMed, the US database on medicines and breastfeeding, gives 250 to 375 mg of DHA and EPA a day as the current advice for nursing mothers.[17] The US FDA considers fish oil up to 3 g a day generally safe as a food.[17]

The DHA in breast milk rises with the dose. In one trial, DHA was 0.21% of the fatty acids in milk with placebo and 1.13% with 1.3 g of DHA a day.[17] With fish oil, the most common complaint is burping with a fishy taste. The smell of breast milk does not change.[17]

Open the answer with sources ›
Can DHA cause bleeding?

At the doses in trials, omega-3 supplements did not raise bleeding overall. A 2024 review of 11 trials with 120,643 people found no difference in bleeding.[26] High doses of purified EPA raised bleeding by 50% in relative terms, but only by 0.6% in absolute terms.[26]

EFSA found no rise in bleeding with EPA and DHA together up to about 5 g a day.[10] Fish oil may still raise INR, a clotting test, in people who take warfarin, and prescription omega-3 labels call for INR checks.[1] People who take a blood thinner should ask a doctor or pharmacist first.[1]

Open the answer with sources ›
Forms and timing
Is algal oil DHA as good as fish oil DHA?

For raising blood DHA, it appears so. In a trial in 74 adults over 14 weeks, DHA and EPA from microalgal oil raised blood levels as well as fish oil.[27] Five of the 6 authors are employed by the company dsm-firmenich.[27] In a 2-week trial in 32 adults, 600 mg of DHA a day from algal oil capsules raised plasma DHA by about 80%, the same as cooked salmon.[18]

Algal oils are a vegetarian source of DHA, and some also contain EPA.[5] They usually give 100 to 300 mg of DHA, as triglycerides.[1] In 11 trials, DHA from algal oil lowered triglycerides by 0.20 mmol/L.[6]

Open the answer with sources ›

References

  1. Omega-3 Fatty Acids: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
  2. Effects of eicosapentaenoic acid versus docosahexaenoic acid on serum lipids: a systematic review and meta-analysis. Wei MY, Jacobson TA Curr Atheroscler Rep, 2011. PMID 21975919
  3. Omega-3 fatty acid addition during pregnancy. Middleton P, Gomersall JC, Gould JF, Shepherd E, Olsen SF, Makrides M Cochrane Database Syst Rev, 2018. PMID 30480773
  4. Docosahexaenoic Acid and Bronchopulmonary Dysplasia in Preterm Infants. Collins CT, Makrides M, McPhee AJ, Sullivan TR, Davis PG, Thio M, et al. N Engl J Med, 2017. PMID 28355511
  5. Omega-3 Supplements: What You Need To Know. NIH National Center for Complementary and Integrative Health, 2024. www.nccih.nih.gov
  6. A meta-analysis shows that docosahexaenoic acid from algal oil reduces serum triglycerides and increases HDL-cholesterol and LDL-cholesterol in persons without coronary heart disease. Bernstein AM, Ding EL, Willett WC, Rimm EB J Nutr, 2012. PMID 22113870

Review history

  1. 9 Nov 2026CheckedReviewerChecked every claim against its source.
  2. 9 Nov 2026Page createdResearcherFirst edition, written from PubMed and public health sources.