Home Ingredients Stearidonic Acid (SDA, Plant Omega-3)
Cardiovascular

Stearidonic Acid (SDA, Plant Omega-3)

Evidence Level
Moderate
7 Clinical Trials
5 Documented Benefits
3/5 Evidence Score

Stearidonic acid (SDA, 18:4 n-3) is a plant omega-3 fatty acid found in oils from echium, Buglossoides (the source of Ahiflower) and genetically modified soybeans. The body can make long-chain omega-3s from the plant fat ALA, but the first step, run by the delta-6-desaturase enzyme, is slow and limits how much ALA becomes EPA. SDA is already one step past that bottleneck, so the body turns it into EPA far more readily than it converts ALA from flax. SDA-rich oils therefore raise the omega-3 index and red-cell EPA more than flax does, which is why SDA is often described as sitting between plant ALA and fish oil. The catch is that SDA raises EPA but barely raises DHA, so it does not fully replace fish or algal oil. In controlled trials, SDA-rich echium oil raised EPA without lowering blood triglycerides or cholesterol, so its measured effects so far are on omega-3 status, not blood fats.

Studied Dose Trials used SDA-rich oils giving about 0.75 to 5.2 g of SDA a day for 3 to 16 weeks: echium oil (1.2 to 2 g SDA/day), SDA-enriched soybean oil (about 3.7 to 4.2 g/day), and Ahiflower (Buglossoides) oil (roughly 1.8 g SDA in 9 to 10 mL).
Active Compound Stearidonic acid (SDA, 18:4 n-3), a plant omega-3 and the delta-6-desaturase product of ALA.

Benefits

Raises the omega-3 index, a heart-health marker

The omega-3 index is the share of EPA plus DHA in red blood cell membranes, and a higher value is associated in population research with lower cardiovascular risk. SDA-rich soybean and plant oils raised this index consistently across controlled trials, by about 20 percent over 16 weeks. The rise came from EPA; DHA did not change.

Supported by Trial 2, Trial 5

Raises EPA more efficiently than flax ALA

SDA sits one step past the delta-6-desaturase bottleneck, so the body converts it to EPA more readily than it converts ALA from flax. In a 28-day head-to-head trial, tissue EPA rose more with Ahiflower (Buglossoides) oil than with flax oil, and an earlier study put SDA at about four times the efficiency of ALA for raising tissue EPA. Conversion is still only partial.

Supported by Trial 2, Trial 3

Effect on blood triglycerides and cholesterol

Two randomized controlled trials in overweight adults or adults with high triglycerides tested SDA-rich echium oil against a control oil. Red-cell EPA rose, but serum triglycerides and other blood lipids did not change. So although SDA lifts omega-3 status, it has not been shown to lower blood fats the way higher-dose EPA and DHA from fish oil can.

Supported by Trial 6, Trial 2

Plant-based, sustainable way to lift EPA

For people who avoid fish, SDA-rich oils from echium, Buglossoides (Ahiflower) and SDA soybean offer a land-based route to higher EPA. Trials report them as safe and well tolerated over several weeks, with no clinically meaningful changes in liver, kidney or blood-count safety tests. Because they raise EPA but little DHA, they supplement rather than replace marine or algal oil.

Supported by Trial 5, Trial 2

Omega-3 status and an inflammatory marker

In one placebo-controlled trial, the highest dose of Ahiflower oil raised production of interleukin-10, an anti-inflammatory signal measured in stimulated blood cells in the laboratory. No trial of SDA has measured a clinical inflammatory outcome or a heart-disease outcome, so this is a laboratory marker rather than a proven health effect.

Supported by Trial 1, Trial 5

Mechanism of action

1

Bypasses the delta-6-desaturase bottleneck

Making EPA from the plant omega-3 ALA requires the enzyme delta-6-desaturase to act first, and that step is slow in people, which is why little dietary ALA becomes EPA. SDA is the direct product of that enzyme, so it enters the pathway already past the rate-limiting step and is elongated and desaturated to EPA more efficiently.

2

Raises EPA and DPA but not DHA

The remaining enzyme steps readily carry SDA forward to EPA and on to docosapentaenoic acid (DPA), which is why red-cell EPA climbs. The final conversion to DHA needs another slow desaturation step, so DHA levels stay largely unchanged. This is the main reason SDA is not equivalent to fish or algal oil.

3

Incorporation into cell membranes (omega-3 index)

EPA made from SDA is built into red blood cell and other cell membranes, raising the omega-3 index. Membrane EPA can shift the balance of signaling molecules the body makes from fatty acids, the proposed basis for omega-3 effects, though SDA trials measured membrane EPA rather than clinical endpoints.

Clinical trials

1
SDA-Enriched Soybean Oil and the Omega-3 Index (RCT)
PubMed

Randomized, double-blind, placebo-controlled multicenter trial of SDA-enriched soybean oil (4.2 g SDA/day), purified EPA or control soybean oil for 12 weeks (Lemke et al. 2010, Am J Clin Nutr)

252 overweight adults assigned to SDA-enriched soybean oil, EPA or control oil.

After 12 weeks the omega-3 index was 4.69% with SDA, 4.84% with EPA and 4.15% with control; both SDA and EPA beat control (SDA P=0.006). SDA raised the index by raising red-cell EPA, not DHA. No adverse treatment-related effects were reported. This is an omega-3 status marker, not a heart-disease outcome.

2
SDA Soybean Oil vs EPA on the Omega-3 Index
PubMed

Randomized controlled trial comparing SDA-enriched soybean oil (about 3.7 g SDA/day) with regular soybean oil, with or without added EPA, over 16 weeks (Harris et al. 2008, Lipids)

45 overweight healthy volunteers; 33 analyzed per protocol (11 per group).

The omega-3 index rose 19.5% with SDA and 25.4% with EPA versus control, while DHA did not change in any group. SDA raised red-cell EPA with about 17% of the efficiency of EPA itself. Serum lipids, blood pressure, heart rate and platelet function were not changed.

3
Metabolism of SDA in Humans vs ALA and EPA
PubMed

Double-blind, parallel-group study giving encapsulated SDA, ALA or EPA at 0.75 then 1.5 g/day for 3 weeks each (James et al. 2003, Am J Clin Nutr)

45 healthy men and postmenopausal women (15 per group).

SDA raised EPA and DPA in red cells and plasma phospholipids but did not raise DHA. For raising tissue EPA the relative effectiveness was EPA 1, SDA 0.3 and ALA 0.07, so SDA was about four times as effective as ALA but well below EPA itself.

4
SDA and EPA Dose-Response on Red-Cell EPA
PubMed

Randomized, controlled, parallel-group dose-ranging study of SDA (0.43 to 5.2 g/day) or EPA (0.44 to 2.7 g/day) versus safflower oil for 12 weeks (Krul et al. 2012, Prostaglandins Leukot Essent Fatty Acids)

131 healthy adults.

Red-cell EPA rose with SDA and EPA at nearly all doses, except the lowest 0.43 g/day SDA arm. The SDA-to-EPA conversion efficiency fell as the dose rose, from about 41% at low intakes to about 17% at high intakes, so larger SDA doses give diminishing returns.

5
Plant Omega-3 Oils in High-Triglyceride Adults (RCT)
PubMed

Randomized, double-blind, placebo-controlled crossover trial of foods enriched with linseed (ALA), echium (2 g SDA/day) or microalgae (DHA) oil versus sunflower oil over 10 weeks (Dittrich et al. 2015, Eur J Nutr)

59 adults with triglycerides of 1.5 mmol/L or higher.

Red-cell EPA rose about 73% in the SDA (echium) group, more than with linseed oil, but blood lipids did not change with echium oil. Total and LDL cholesterol fell with the linseed and sunflower oils instead. So echium SDA raised omega-3 status without improving blood lipids.

6
Echium Oil SDA and Serum Triglycerides (RCT)
PubMed

Randomized, double-blind, placebo-controlled crossover trial of 10 g/day echium oil (1.2 g SDA) versus high-oleic sunflower oil for 6 weeks (Pieters and Mensink 2015, Eur J Clin Nutr)

36 healthy overweight and slightly obese adults; 32 completed.

Echium oil raised red-cell EPA by about 0.14 percentage points versus control but did not change serum triglycerides, other blood lipids or the overall omega-3 index. The authors concluded that at this dose SDA from echium oil does not lower triglycerides.

7
Ahiflower (Buglossoides) Oil vs Flax Oil (Phase I RCT)
PubMed

Parallel-group, randomized, double-blind phase I trial of 9.1 g/day Ahiflower oil (20% SDA) versus flax seed oil for 28 days (Lefort et al. 2016, J Nutr Sci)

40 healthy adults.

EPA rose in plasma and all blood cell types in both groups, but more with Ahiflower than with flax; plasma and mononuclear-cell DPA also rose more with Ahiflower. Safety labs were unchanged. The trial reported a significant time-by-treatment difference rather than a fixed multiple, and DHA did not rise meaningfully.

Side effects and drug interactions

Common Potential side effects

Generally well tolerated in trials lasting up to 16 weeks, with no clinically meaningful changes in liver, kidney, blood-count or blood-pressure safety tests.
As with any oil supplement, mild digestive complaints such as burping, an oily aftertaste or loose stools can occur; taking it with food helps.
SDA raises EPA but has little effect on DHA, so it is not a full substitute for fish or algal oil when DHA is the goal, for example during pregnancy.
Raising EPA has a theoretical blood-thinning effect at high omega-3 intakes, though the SDA trials reported no change in platelet function at the doses tested.

Important Drug interactions

Anticoagulant and antiplatelet drugs (for example warfarin, aspirin, clopidogrel): high omega-3 intakes can be mildly blood-thinning in theory, although SDA trials found no change in platelet function; tell your doctor if you take these.
No formal drug-interaction studies of SDA oils have been published; if you take prescription medicines, ask your doctor or pharmacist before adding a concentrated omega-3 oil.
Before surgery: discuss any high-dose omega-3 oil with your surgeon, as is commonly advised for fish oil.

Standardized & branded forms of Stearidonic Acid (SDA, Plant Omega-3)

Trademarked forms of Stearidonic Acid (SDA, Plant Omega-3) with their own profiles on NutraSmarts. Results from one branded form do not automatically carry over to another, so check each profile for the studies run on that specific product:

Anti-Inflammatory
Ahiflower® (Buglossoides Plant Omegas — Stratum Nutrition)
Ahiflower® is a plant oil pressed from Buglossoides arvensis seeds that supplies a mix of…

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Frequently asked questions about Stearidonic Acid (SDA, Plant Omega-3)

Is stearidonic acid better than flaxseed for omega-3?

For raising EPA, gram for gram, yes. Flaxseed gives ALA, which the body converts to EPA only slightly because the first enzyme step is slow. SDA is already past that step, so trials show SDA-rich oils raise red-cell EPA and the omega-3 index several times more than flax. SDA does not raise DHA, though, and flaxseed also brings fiber and lignans that SDA oils do not.

Does stearidonic acid replace fish oil?

Not fully. SDA reliably raises EPA, but it barely raises DHA, and fish and algal oils supply both EPA and DHA directly. SDA is best thought of as sitting between plant ALA and marine oil: a plant-based, sustainable way to lift EPA for people who avoid fish, rather than a complete swap for fish oil.

Does stearidonic acid lower triglycerides?

In the controlled trials done so far, no. Two randomized trials in overweight or high-triglyceride adults found SDA-rich echium oil raised EPA but did not change triglycerides or cholesterol. High-dose EPA and DHA from fish oil can lower triglycerides, but SDA at the doses studied has not been shown to do the same.

How much SDA do the studies use, and where does it come from?

Trials used roughly 1 to 5 grams of SDA a day from echium oil, Buglossoides (Ahiflower) oil or SDA-enriched soybean oil, for several weeks. Larger doses give diminishing returns, because the conversion to EPA becomes less efficient as the dose rises. Follow the product label, and talk to your doctor if you take blood thinners.

What is Stearidonic Acid?

Stearidonic acid (SDA, 18:4 n-3) is a plant omega-3 fatty acid found in oils from echium, Buglossoides (the source of Ahiflower) and genetically modified soybeans.

What is Stearidonic Acid used for?

Stearidonic Acid is researched primarily for Cardiovascular. The omega-3 index is the share of EPA plus DHA in red blood cell membranes, and a higher value is associated in population research with lower cardiovascular risk.

What is the recommended dosage of Stearidonic Acid?

The clinically studied dose is Trials used SDA-rich oils giving about 0.75 to 5.2 g of SDA a day for 3 to 16 weeks: echium oil (1.2 to 2 g SDA/day), SDA-enriched soybean oil (about 3.7 to 4.2 g/day), and Ahiflower (Buglossoides) oil (roughly 1.8 g SDA in 9 to 10 mL). Always follow the product label and check with a healthcare provider for personal advice.

Is Stearidonic Acid safe, and does it have side effects?

For most healthy adults, Stearidonic Acid is well tolerated at studied doses. Reported effects can include: Generally well tolerated in trials lasting up to 16 weeks, with no clinically meaningful changes in liver, kidney, blood-count or blood-pressure safety tests. It may also interact with some medications. Stearidonic Acid is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Stearidonic Acid interact with any medications?

Possible interactions include: Anticoagulant and antiplatelet drugs (for example warfarin, aspirin, clopidogrel): high omega-3 intakes can be mildly blood-thinning in theory, although SDA trials found no change in platelet function; tell your doctor if you take these. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Stearidonic Acid?

NutraSmarts rates the evidence for Stearidonic Acid as Moderate (3 out of 5). It is backed by 7 clinical trials and 11 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(11 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Lemke SL, Vicini JL, Su H, Goldstein DA, Nemeth MA, Krul ES, Harris WS. Dietary intake of stearidonic acid-enriched soybean oil increases the omega-3 index: randomized, double-blind clinical study of efficacy and safety. Am J Clin Nutr. 2010;92(4):766-75. doi: 10.3945/ajcn.2009.29072.PubMedUsed to support: Randomized, double-blind, placebo-controlled trial in 252 overweight adults: SDA-enriched soybean oil (4.2 g SDA/day) raised the erythrocyte omega-3 index to 4.69% versus 4.15% for control (P=0.006) over 12 weeks, through higher red-cell EPA and not DHA, with no adverse treatment-related effects. An omega-3 status marker, not a cardiovascular outcome.
  2. Harris WS, Lemke SL, Hansen SN, Goldstein DA, DiRienzo MA, Su H, Nemeth MA, Taylor ML, Ahmed G, George C. Stearidonic acid-enriched soybean oil increased the omega-3 index, an emerging cardiovascular risk marker. Lipids. 2008;43(9):805-11. doi: 10.1007/s11745-008-3215-0.PubMedUsed to support: Randomized controlled trial in 45 overweight volunteers (33 per protocol): 16 weeks of SDA-enriched soybean oil (about 3.7 g SDA/day) raised the omega-3 index 19.5% versus 25.4% with EPA, with no change in DHA. SDA raised red-cell EPA at about 17% of the efficiency of EPA; serum lipids, blood pressure, heart rate and platelet function were unchanged.
  3. James MJ, Ursin VM, Cleland LG. Metabolism of stearidonic acid in human subjects: comparison with the metabolism of other n-3 fatty acids. Am J Clin Nutr. 2003;77(5):1140-5. doi: 10.1093/ajcn/77.5.1140.PubMedUsed to support: Double-blind, parallel-group study in 45 healthy adults: dietary SDA raised EPA and docosapentaenoic acid in red cells and plasma phospholipids but not DHA. The relative effectiveness for raising tissue EPA was EPA 1, SDA 0.3, ALA 0.07, so SDA was roughly four times as effective as ALA but well below EPA itself.
  4. Krul ES, Lemke SL, Mukherjea R, Taylor ML, Goldstein DA, Su H, Liu P, Lawless A, Harris WS, Maki KC. Effects of duration of treatment and dosage of eicosapentaenoic acid and stearidonic acid on red blood cell eicosapentaenoic acid content. Prostaglandins Leukot Essent Fatty Acids. 2012;86(1-2):51-9. doi: 10.1016/j.plefa.2011.10.005.PubMedUsed to support: Randomized, controlled, parallel-group dose-ranging study in 131 healthy adults: SDA (0.43 to 5.2 g/day) raised red-cell EPA at all doses except the lowest, in a dose- and time-dependent way, but the SDA-to-EPA conversion efficiency fell from about 41% at low intakes to about 17% at high intakes.
  5. Maki KC, Rains TM. Stearidonic acid raises red blood cell membrane eicosapentaenoic acid. J Nutr. 2012;142(3):626S-629S. doi: 10.3945/jn.111.153858.PubMedUsed to support: Review summarizing a randomized controlled study of SDA and EPA intakes over 12 weeks: dietary SDA raised red-cell %EPA across a range of intakes, with relative efficiency versus EPA declining from about 41% to 16.7% as the SDA dose rose. Prior studies put SDA-to-EPA efficiency at roughly 16 to 30%.
  6. Lemke SL, Maki KC, Hughes G, Taylor ML, Krul ES, Goldstein DA, Su H, Rains TM, Mukherjea R. Consumption of stearidonic acid-rich oil in foods increases red blood cell eicosapentaenoic acid. J Acad Nutr Diet. 2013;113(8):1044-56. doi: 10.1016/j.jand.2013.04.020.PubMedUsed to support: Randomized, double-blind, controlled parallel-arm trial in healthy adults: SDA-enriched soybean oil baked into foods and beverages raised red-cell %EPA to 0.85% at 12 weeks versus 0.50% for control and 2.17% for EPA. Other efficacy outcomes, including serum lipids, did not differ between groups.
  7. Miles EA, Banerjee T, Calder PC. The influence of different combinations of gamma-linolenic, stearidonic and eicosapentaenoic acids on the fatty acid composition of blood lipids and mononuclear cells in human volunteers. Prostaglandins Leukot Essent Fatty Acids. 2004;70(6):529-38. doi: 10.1016/j.plefa.2003.11.008.PubMedUsed to support: Randomized 12-week study of oil blends in healthy young men: SDA (around 1 g/day) combined with GLA increased the proportion of EPA in some blood lipid fractions, supporting SDA as a precursor that can raise EPA status, while SDA alone at up to 1 g/day did not itself appear in the lipid fractions measured.
  8. Dittrich M, Jahreis G, Bothor K, Drechsel C, Kiehntopf M, Blüher M, Dawczynski C. Benefits of foods supplemented with vegetable oils rich in α-linolenic, stearidonic or docosahexaenoic acid in hypertriglyceridemic subjects: a double-blind, randomized, controlled trial. Eur J Nutr. 2015;54(6):881-93. doi: 10.1007/s00394-014-0764-2.PubMedUsed to support: Randomized, double-blind, placebo-controlled crossover trial in 59 adults with triglycerides of 1.5 mmol/L or higher: echium (SDA) oil providing 2 g SDA/day raised red-cell EPA about 73%, more than linseed oil, but did not change blood lipids, whereas cholesterol fell with linseed and sunflower oils. SDA raised omega-3 status without improving blood lipids.
  9. Pieters DJ, Mensink RP. Effects of stearidonic acid on serum triacylglycerol concentrations in overweight and obese subjects: a randomized controlled trial. Eur J Clin Nutr. 2015;69(1):121-6. doi: 10.1038/ejcn.2014.193.PubMedUsed to support: Randomized, double-blind, placebo-controlled crossover trial in 36 overweight and slightly obese adults: 10 g/day echium oil (1.2 g SDA) for 6 weeks raised red-cell EPA by about 0.14 percentage points but did not change serum triglycerides, other lipids or the omega-3 index. At this dose SDA from echium oil did not lower triglycerides.
  10. Lefort N, LeBlanc R, Giroux MA, Surette ME. Consumption of Buglossoides arvensis seed oil is safe and increases tissue long-chain n-3 fatty acid content more than flax seed oil - results of a phase I randomised clinical trial. J Nutr Sci. 2016;5:e2. doi: 10.1017/jns.2015.34.PubMedUsed to support: Parallel-group, randomized, double-blind phase I trial in 40 healthy adults: 28 days of Ahiflower (Buglossoides arvensis) oil (20% SDA) raised plasma and blood-cell EPA and DPA more than flax seed oil (time-by-treatment interactions P<=0.01), with no clinically significant safety changes. EPA accrual was greater with Ahiflower; DHA did not rise meaningfully.
  11. Lefort N, LeBlanc R, Surette ME. Dietary Buglossoides Arvensis Oil Increases Circulating n-3 Polyunsaturated Fatty Acids in a Dose-Dependent Manner and Enhances Lipopolysaccharide-Stimulated Whole Blood Interleukin-10-A Randomized Placebo-Controlled Trial. Nutrients. 2017;9(3):261. doi: 10.3390/nu9030261.PubMedUsed to support: Randomized, double-blind, placebo-controlled trial in 88 healthy adults: Ahiflower oil raised plasma and mononuclear-cell EPA, ALA and DPA dose-dependently over 28 days, but not DHA, and the highest dose raised stimulated whole-blood interleukin-10. A grant from the Ahiflower producer partially supported the work. Supports the EPA-status and laboratory IL-10 observations.