Hemp Seeds: Omega-3, Omega-6 and GLA

Table of Contents

1. The Fats in a Hemp Seed
2. GLA and SDA: The Two Unusual Fats
3. The Omega-6 to Omega-3 Ratio
4. What the Research Says About Ratios
5. From Plant Omega-3 to EPA and DHA
6. The Human Trials of Hemp Seed Oil
7. Skin and Atopic Dermatitis
8. GLA Research From Other Oils
9. Hemp, Flax and Chia Compared
10. Rancidity, Light and Storage
11. Hemp Seed Oil Is Not CBD Oil
12. What Is Not Known
13. Who the Research Raises Cautions For
14. Connections
15. Key Research Papers
16. Featured Videos

The Fats in a Hemp Seed

Shelled hemp seed (“hemp hearts”) is close to half fat by weight, and most of that fat is polyunsaturated. A polyunsaturated fatty acid is a fat molecule with two or more double bonds in its carbon chain. Those double bonds keep the fat liquid at room temperature, make it useful to cell membranes, and also make it easy to damage with oxygen, a point that returns in the storage section below.

The figures below come from the USDA FoodData Central entry for hulled hemp seed (FDC ID 170148). The “share of total fat” column is this page's own arithmetic from those figures and is approximate.

The labels need a word of explanation. “Omega-3” and “omega-6” describe where the first double bond sits when the carbon chain is counted from its tail end: three carbons in, or six. The two families are not interchangeable; the body handles them through separate chains of reactions and cannot turn one into the other. The numbers in brackets (18:2, 18:3) give the chain length and the number of double bonds.

From these USDA figures linoleic acid outweighs ALA by roughly 3 to 1. A 2025 review of hempseed and heart health gives the omega-6 to omega-3 ratio of hempseed oil as between 3:1 and 5:1 (Kaçar 2025); the spread reflects differences between varieties and growing conditions. A study that followed one traditional Chinese hemp variety through seed development found that the oil accumulates along an S-shaped curve as the seed grows, with the genes and compounds of the linoleic-acid and ALA pathways changing from stage to stage (Nie 2024). The fat profile of a seed is not fixed, which is one reason published figures differ.

GLA and SDA: The Two Unusual Fats

Most seed oils carry linoleic acid and, sometimes, ALA. Hemp seed oil also carries small amounts of two fatty acids that the body normally makes for itself, one step further down each family's chain:

• Gamma-linolenic acid (GLA) is an omega-6 made in the body from linoleic acid. It is the fatty acid that evening primrose and borage oils are sold for (Bamford 2013).
• Stearidonic acid (SDA) is an omega-3 made in the body from ALA. It is uncommon in foods, and hemp seed is one of the few everyday foods that contains it.

Why this matters is the first step of the conversion chain. To turn linoleic acid into GLA, or ALA into SDA, the body uses an enzyme called delta-6-desaturase, and that step is slow. The 2025 review notes that GLA and SDA “bypass the rate-limiting δ-6-desaturase enzyme” (Kaçar 2025): having already passed that bottleneck, they can move on to the longer fatty acids more readily than their parent fats. How much difference this makes depends on the amounts eaten, and the amounts in hemp seed are small — about 0.4 g of GLA and 0.2 g of SDA in three tablespoons of hemp hearts, by the USDA figures above.

The Omega-6 to Omega-3 Ratio

The ratio is simply the amount of omega-6 fat in a food or a diet divided by the amount of omega-3 fat. The reason anyone cares about it is that the two families compete. Linoleic acid and ALA are processed by the same desaturase and elongase enzymes, so a very large supply of one can slow the conversion of the other. A hemp-versus-flax trial set out this rationale directly: an excessive intake of one essential fatty acid over the other “may interfere with the metabolism of the other while the metabolisms of LA and ALA compete for the same enzymes” (Schwab 2006).

The two families also lead to signalling molecules with different effects. Arachidonic acid, a long-chain omega-6 made from linoleic acid, is the raw material for many of the hormone-like messengers that drive inflammation, blood clotting and blood-vessel tightening; EPA, a long-chain omega-3, feeds messengers that tend to act more gently and help switch inflammation off. A review of the ratio summarised this competition: the metabolites of the two classes “can powerfully influence (often in different directions) inflammatory responses, vascular reactivity, and platelet aggregation” (Harris 2006).

Hemp, at roughly 3:1, sits between the seeds dominated by omega-6 (sunflower, pumpkin) and the seeds dominated by omega-3 (flax, chia). That middle position is what promotional writing calls “balanced” or “optimal”. Whether a ratio is the right way to judge a food is the question of the next section.

What the Research Says About Ratios

Researchers disagree about how useful the ratio is, and the disagreement is worth setting out in both directions.

The case for the ratio. In a widely cited 2002 review, Artemis Simopoulos argued that human beings evolved on a diet with an omega-6 to omega-3 ratio of about 1, while Western diets run at about 15 to 1 or higher, and that “a very high omega-6/omega-3 ratio, as is found in today's Western diets, promote[s] the pathogenesis of many diseases”. The review gathered studies in which different ratios were linked to different outcomes: a ratio of 4:1 in secondary prevention of heart disease was associated with a 70% decrease in total mortality, a ratio of 2–3:1 suppressed inflammation in rheumatoid arthritis, and a ratio of 5:1 helped people with asthma while 10:1 had adverse effects. The review also concluded that “the optimal ratio may vary with the disease under consideration” (Simopoulos 2002). A 2023 narrative review of ALA likewise set out to “investigate the relevant omega-6/omega-3 ratio” for maintaining ALA's benefits (Bertoni 2023), and the 2025 hempseed review uses the ratio as one of hemp's selling points (Kaçar 2025).

The case against. William Harris, a lipid researcher, reviewed the same question in 2006 and reached the opposite conclusion. He wrote that although the ratio is “initially appealing, there are few human experimental and clinical trial data to support this view,” and that studies in the aggregate “suggest that the ratio is, both on theoretical and evidential grounds, of little value.” Measures based on the omega-3 fats alone, especially EPA and DHA, “appear to hold the greatest promise” (Harris 2006). One part of the argument is simple arithmetic: a ratio does not distinguish a diet with a little of both from a diet with a lot of both, and it treats every omega-3 (ALA, EPA, DHA) as equivalent, which the conversion data below show they are not.

What this means for hemp. Both sides agree on the underlying facts: the two families compete for enzymes, and long-chain omega-3 status matters. They disagree about whether a food's ratio predicts anything about health. A single food also does not set a diet's ratio, which depends on everything else eaten. No trial has tested whether eating hemp seed specifically, because of its ratio, changes a health outcome.

From Plant Omega-3 to EPA and DHA

The omega-3 in hemp seed is mostly ALA, the short, 18-carbon form. The omega-3 fats most studied for the heart, the brain and the eye are the long-chain forms EPA (20 carbons) and DHA (22 carbons), found ready-made in oily fish and algae. The body can lengthen ALA into EPA and DHA, but not very well. A review of the human evidence by Burdge and Calder found that increasing ALA intake for weeks to months raises EPA in blood and cells but produces no increase in DHA, which “may even decline in some pools at high alphaLNA intakes.” Tracer studies show that conversion to EPA “is limited in men” and that the further step to DHA “is very low,” with conversion somewhat greater in women, possibly because of oestrogen (Burdge 2005). The walnut page covers this conversion in more detail: Walnuts: ALA Omega-3 and the Brain.

SDA was studied in people as a possible way round the bottleneck. In a double-blind trial in healthy men and postmenopausal women (15 per group), capsules of SDA, ALA or EPA were taken at 0.75 g and then 1.5 g a day, for three weeks at each dose. SDA raised EPA and docosapentaenoic acid (DPA, the step between EPA and DHA) in red cells and plasma, but not DHA. The researchers estimated the relative power of the three fats to raise tissue EPA as 1 : 0.3 : 0.07 for EPA : SDA : ALA (James 2003). In other words, gram for gram SDA was about four times as effective as ALA at raising EPA, and EPA itself about three times as effective as SDA.

Two cautions keep this in proportion. First, the trial used purified SDA at 0.75–1.5 g a day; three tablespoons of hemp hearts supply about 0.19 g. Second, neither SDA nor ALA raised DHA. Hemp seed is a source of plant omega-3, not a substitute for the long-chain forms. For the fish side of the comparison, see Salmon: Omega-3 EPA and DHA.

The Human Trials of Hemp Seed Oil

Only a handful of controlled trials have given people hemp seed oil and measured their blood fats. They differ in dose, length and who took part, and their results are mixed.

Read together, the trials show a dose story. At 2 g of oil a day (Kaul 2008), hemp seed oil changed nothing measurable in plasma fatty acids over three months; the authors concluded that two capsules of any of the oils tested “may not provide the desired or expected result over a 3 month period.” At 3 g a day in children (Del Bo' 2019), red-cell membranes shifted. At 30 ml a day, roughly two tablespoons (Schwab 2006), the blood fatty-acid pattern moved clearly in the direction of the oil's composition. In none of these trials did hemp seed oil significantly lower cholesterol compared with its comparison, and none was long enough or large enough to measure heart attacks or other clinical events.

Blood lipids across many oils were also pooled in a 2018 network meta-analysis of 54 randomised trials comparing 13 oils and solid fats, hempseed oil among them. Safflower and rapeseed oils ranked best for lowering LDL cholesterol. The abstract lists the oils that lowered LDL more than butter; hempseed oil is not among them, and the abstract gives no separate result for it (Schwingshackl 2018). For the wider hemp and heart question, see Hemp Seeds: Heart and Blood Pressure.

Skin and Atopic Dermatitis

The idea that hemp seed oil might help the skin rests on the role of polyunsaturated fats in the skin's outer barrier, the layer of lipids that keeps water in and irritants out. In atopic dermatitis (eczema) that barrier is weak. Linoleic acid is a building block of the barrier lipids, and oils rich in GLA have been tried for eczema because of their GLA content (Bamford 2013).

The one trial of dietary hemp seed oil in eczema is the Finnish study above. Patients took hempseed oil and olive oil in turn over 20 weeks. After the hempseed oil period, transepidermal water loss (the amount of water evaporating through the skin) fell, though not significantly (p = 0.074); patients' reports of skin dryness and itchiness improved (p = 0.027); and their use of skin medications fell (p = 0.024). The authors suggested the improvement came from “the balanced and abundant supply of PUFAs in this hempseed oil” (Callaway 2005).

Several features limit how far this result reaches. The trial was single-blind, so patients may have known which oil they were taking; the improvements in dryness and itch came from a questionnaire; and the abstract does not report the number of patients or the daily dose. No larger trial has repeated it. The 2021 scoping review of hemp research, which collected 65 primary studies from 2009 to 2019 (18 of them clinical), concluded that evidence for hemp-specific interventions is “still preliminary, with limited high quality clinical evidence for any specific therapeutic indication” (Lim 2021). For the condition itself, see Eczema.

GLA Research From Other Oils

Most of what is known about GLA in people comes from evening primrose oil and borage oil, not hemp. They are sold as concentrated GLA sources, and the trials gave them as supplements. Their results cannot be transferred to hemp, but they set the context for any claim that hemp's GLA helps the skin.

A 2013 Cochrane review pooled 27 randomised trials with 1,596 participants: 19 of evening primrose oil and 8 of borage oil, taken by mouth for eczema. Evening primrose oil “failed to significantly increase improvement in global eczema symptoms” compared with placebo, whether symptoms were rated by patients or by doctors, and borage oil also failed to beat placebo. The reviewers concluded that the two oils “lack effect on eczema,” that the confidence intervals were narrow enough to make further trials “hard to justify,” and that the side effects, mostly mild and gastrointestinal, were similar to placebo. The review also noted a report that evening primrose oil may increase bleeding in people taking warfarin (Bamford 2013).

Two things follow. First, the null result for concentrated GLA oils makes it unlikely that GLA alone explains the Finnish hemp result; the authors themselves credited the whole fatty-acid supply. Second, a GLA trial is not a hemp trial, and a hemp trial is not a GLA trial. Each needs to be read for what it tested.

Hemp, Flax and Chia Compared

Hemp, flaxseed and chia are the three seeds most often sold for their omega-3. They differ more than the shared label suggests.

The head-to-head trial gives the clearest picture. Schwab and colleagues described the two oils as containing LA and ALA “in almost opposite ratios”. After four weeks on each, blood fats reflected what was eaten: more LA and GLA after hemp oil, more ALA after flax oil, and less arachidonic acid in cholesteryl esters after flax oil than after hemp oil. Neither oil beat the other on fasting cholesterol, glucose, insulin or clotting factors (Schwab 2006). In the larger Canadian trial at a much lower dose, flax oil raised ALA only for a while and hemp oil changed no plasma fatty acid (Kaul 2008).

The 2025 review compares hemp with flax and chia and emphasises hemp's “unique fatty acid composition” and its additional protein and bioactive compounds (Kaçar 2025). By sheer quantity of ALA, flax and chia carry more. Which pattern is preferable is the ratio question above, on which researchers do not agree. For the omega-3 detail on the other two seeds, see Flaxseed: ALA Omega-3 and Heart Health and Chia Seeds: ALA Omega-3.

Rancidity, Light and Storage

The double bonds that make polyunsaturated fats valuable also make them easy to oxidise. Oxygen attacks the carbon next to each double bond, forming peroxides and then the smaller breakdown products that give rancid oil its paint-like, fishy or bitter taste. The more double bonds a fat has, the faster this happens, and hemp seed oil is made up mostly of fats with two and three.

Two storage studies of cold-pressed hemp seed oil measured how quickly this goes and what slows it:

• An Italian study pressed oil from one hemp variety and stored it for 270 days in polypropylene, clear glass, amber glass, or amber glass wrapped in aluminium foil, either at 25 °C in diffused light or at 10 °C in the dark. Peroxides and related oxidation markers were measured at intervals. The authors describe hemp seed oil's high unsaturated-fat content as giving it “high sensitivity to oxidative and photo-oxidative degradations that can lead to rancidity despite the presence of antioxidant compounds,” and found that oil in foil-wrapped amber glass at refrigerated temperature was the best protected (Bonazza 2024).
• A second Italian study followed filtered and unfiltered cold-pressed oil for 12 weeks in clear glass bottles. It identified chlorophyll, the pigment that gives hemp oil its green colour, together with the polyunsaturated fats, as the factors that “inevitably accelerate its oxidative deterioration, especially in the presence of light.” Filtering removed much of the chlorophyll and made the oil more resistant to light-driven oxidation, at the cost of lower amounts of carotenoids, tocopherols, polyphenols and squalene (Lo Turco 2023).

Light, warmth and air are therefore the three things these studies identify as speeding hemp oil's breakdown, which is why it is sold in dark bottles and why it is generally used unheated, in dressings and on finished food, rather than for frying. Whole seeds are better protected than hulled hearts or oil because the shell shields the kernel. For the broader debate about high-linoleic seed oils in the diet, see Seed Oils.

Hemp Seed Oil Is Not CBD Oil

Every trial on this page tested hemp seed oil, the culinary oil pressed from the seed. CBD (cannabidiol) products are extracts of the flowers and leaves. A review of hemp as food explains the division: the hemp inflorescence (flowering top) is rich in cannabinoids such as CBD, while hempseed is a source of essential amino acids, fatty acids, minerals, vitamins and fibre (Cerino 2021). A pharmacology review on differentiating cannabis products separates hemp (low-THC cultivars) from marijuana, and hemp seed and its oil, valued for nutrition, from CBD, valued as a medicinal compound (Salehi 2022).

The labels can be confusing. Some products called “full-spectrum hemp oil” are blends of seed oil and flower extract. Research on CBD extracts says nothing about the fatty acids in seed oil, and the fatty-acid trials above say nothing about CBD. The seed itself carries cannabinoids only as a surface residue picked up during harvest; that issue, and its relevance to drug tests, is covered in Hemp Seeds: THC Residue and Safety.

What Is Not Known

• Clinical outcomes. No trial of hemp seed or hemp seed oil has measured heart attacks, strokes or deaths. The trials measured blood fatty acids and cholesterol, over 4 to 20 weeks.
• The skin result. One small, single-blind trial found symptom improvement in atopic dermatitis (Callaway 2005). It has not been repeated, and the much larger body of GLA-oil trials was null (Bamford 2013).
• Whether the ratio matters. Reviews disagree (Simopoulos 2002; Harris 2006), and no trial has tested a hemp-specific ratio effect on health.
• SDA at food amounts. The SDA conversion data come from purified SDA at several times the amount in a normal serving of hemp seed (James 2003). Whether hemp's small SDA content changes EPA status in people eating ordinary amounts has not been shown.
• Whole seed versus oil. All four fatty-acid trials used the oil. Hemp hearts add protein, fibre and minerals, and no trial has compared the two forms for blood fatty acids.
• Variety and processing. Fatty-acid content varies between hemp varieties (Kaçar 2025) and builds up in stages as the seed develops (Nie 2024), and filtering and storage change the oil's minor compounds (Lo Turco 2023). Trials rarely report enough to know how their oil compares with what is sold.
• The overall evidence base. The 2021 scoping review found most hemp research is preclinical, with “limited high quality clinical evidence for any specific therapeutic indication” (Lim 2021), and the 2025 review calls for “long-term randomized controlled trials” (Kaçar 2025).

Who the Research Raises Cautions For

• People relying on plant seeds for EPA and DHA. The conversion research finds ALA a limited source of long-chain omega-3 and finds no rise in DHA from ALA or SDA (Burdge 2005; James 2003). This matters most for people who eat no fish, and in pregnancy, when the fetus's need for DHA is high (Burdge 2005).
• People taking blood thinners. The hemp oil trials that measured clotting found no change in clotting factors or platelet aggregation (Schwab 2006; Kaul 2008). The GLA review notes a report of increased bleeding with evening primrose oil in a person on warfarin (Bamford 2013); that finding concerns a concentrated GLA supplement, not hemp. Questions about supplements and anticoagulants belong with a clinician.
• People buying “hemp oil” for its fatty acids. A product sold as hemp extract or CBD oil is a different product from hemp seed oil; the ingredient list tells them apart.
• People subject to drug testing. Hemp seed foods can carry surface THC residue; see the THC residue page.
• Anyone storing the oil. The storage studies found hemp seed oil oxidises readily in light and warmth (Bonazza 2024; Lo Turco 2023). Oil that smells or tastes paint-like or bitter has oxidised.

Connections

• Seeds — all seeds on this site
• Hemp Seeds — the main page
• Hemp Seeds — Benefits — the hub for these articles
• Hemp Seeds: Protein and Digestibility
• Hemp Seeds: Heart and Blood Pressure
• Hemp Seeds: THC Residue and Safety
• Walnuts: ALA Omega-3 and the Brain — ALA conversion in detail
• Flaxseed — the omega-3-dominant seed
• Flaxseed: ALA Omega-3 and Heart Health
• Chia Seeds
• Chia Seeds: ALA Omega-3
• Omega-3 Fatty Acids
• Omega-3 and Inflammation Resolution
• Salmon: Omega-3 EPA and DHA — the long-chain forms
• Omega-3 Index — the red-cell test used in the pediatric trial
• Lipid Panel
• Eczema
• Seed Oils — the linoleic-acid debate

Key Research Papers

1. Callaway J, Schwab U, Harvima I, et al. Efficacy of dietary hempseed oil in patients with atopic dermatitis. The Journal of dermatological treatment. 2005;16(2):87-94. PubMed PMID: 16019622
2. Schwab US, Callaway JC, Erkkilä AT, et al. Effects of hempseed and flaxseed oils on the profile of serum lipids, serum total and lipoprotein lipid concentrations and haemostatic factors. Eur J Nutr. 2006;45(8):470-7. PubMed PMID: 17103080
3. Kaul N, Kreml R, Austria JA, et al. A comparison of fish oil, flaxseed oil and hempseed oil supplementation on selected parameters of cardiovascular health in healthy volunteers. J Am Coll Nutr. 2008;27(1):51-8. PubMed PMID: 18460481
4. Del Bo' C, Deon V, Abello F, et al. Eight-week hempseed oil intervention improves the fatty acid composition of erythrocyte phospholipids and the omega-3 index, but does not affect the lipid profile in children and adolescents with primary hyperlipidemia. Food research international (Ottawa, Ont.). 2019;119:469-476. PubMed PMID: 30884679
5. Schwingshackl L, Bogensberger B, Benčič A, et al. Effects of oils and solid fats on blood lipids: a systematic review and network meta-analysis. Journal of lipid research. 2018;59(9):1771-1782. PubMed PMID: 30006369
6. 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. PubMed PMID: 12716664
7. Burdge GC, Calder PC. Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults. Reprod Nutr Dev. 2005;45(5):581-97. PubMed PMID: 16188209
8. Simopoulos AP. The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother. 2002;56(8):365-79. PubMed PMID: 12442909
9. Harris WS. The omega-6/omega-3 ratio and cardiovascular disease risk: uses and abuses. Curr Atheroscler Rep. 2006;8(6):453-9. PubMed PMID: 17045070
10. Bamford JT, Ray S, Musekiwa A, et al. Oral evening primrose oil and borage oil for eczema. Cochrane Database Syst Rev. 2013;2013(4):CD004416. PubMed PMID: 23633319
11. Bertoni C, Abodi M, D'Oria V, et al. Alpha-Linolenic Acid and Cardiovascular Events: A Narrative Review. International journal of molecular sciences. 2023;24(18). PubMed PMID: 37762621
12. Kaçar ÖF, Kose T, Kaya Kaçar H. Dietary hempseed and cardiovascular health: nutritional composition, mechanisms and comparison with other seeds. Frontiers in nutrition. 2025;12:1669375. PubMed PMID: 41132555
13. Nie J, Ma W, Ma X, et al. Integrated Transcriptomic and Metabolomic Analysis Reveal the Dynamic Process of Bama Hemp Seed Development and the Accumulation Mechanism of α-Linolenic Acid and Linoleic Acid. Journal of agricultural and food chemistry. 2024;72(19):10862-10878. PubMed PMID: 38712687
14. Bonazza F, Monti L, Povolo M, et al. Monitoring the Shelf Life of Hemp Seed Oil Stored at Two Temperatures in Different Materials via Near-Infrared (NIR) Spectroscopy. Molecules. 2024;29(23):5577. PubMed PMID: 39683736
15. Lo Turco V, Litrenta F, Nava V, et al. Effect of Filtration Process on Oxidative Stability and Minor Compounds of the Cold-Pressed Hempseed Oil during Storage. Antioxidants (Basel). 2023;12(6):1231. PubMed PMID: 37371962
16. Lim XY, Tan TYC, Muhd Rosli SH, et al. Cannabis sativa subsp. sativa's pharmacological properties and health effects: A scoping review of current evidence. PloS one. 2021;16(1):e0245471. PubMed PMID: 33465140
17. Cerino P, Buonerba C, Cannazza G, et al. A Review of Hemp as Food and Nutritional Supplement. Cannabis and cannabinoid research. 2021;6(1):19-27. PubMed PMID: 33614949
18. Salehi A, Puchalski K, Shokoohinia Y, et al. Differentiating Cannabis Products: Drugs, Food, and Supplements. Frontiers in pharmacology. 2022;13:906038. PubMed PMID: 35833025

PubMed Topic Searches

1. PubMed: hempseed oil and fatty acids in people
2. PubMed: stearidonic acid and EPA in people
3. PubMed: omega-6 to omega-3 ratio and cardiovascular disease
4. PubMed: gamma-linolenic acid and atopic dermatitis
5. PubMed: hemp seed oil oxidative stability

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