What Are the Dangers of Omega-6? Linoleic Acid and Inflammation

Omega-6 is not dangerous at the amounts people eat. Linoleic acid, the main omega-6, is an essential fat the body cannot make; in a systematic review of 15 randomised trials, raising it did not increase a single inflammatory marker, across 30 cohorts and 68,659 people higher blood levels went with 7% lower cardiovascular disease and 22% lower cardiovascular mortality, and Cochrane's review of 19 randomised trials found no harm over one to eight years.^{1, 3, 4, 6} The "dangers" circulating online rest on a mechanism, linoleic acid turning into arachidonic acid and driving inflammation, that the trials have not borne out.³ The one limit is the one that applies to any oil: calories.

• What it is: linoleic acid, an essential polyunsaturated fat in seed oils, nuts, seeds and eggs
• Dangers: none found in trials or cohorts at dietary intakes; no recognised "too much omega-6" syndrome
• Inflammation: linoleic acid neither raises nor lowers inflammatory markers; EPA and DHA lower them modestly at gram doses
• How much: about 4% of energy, roughly 9 g a day; the authorised cholesterol wording applies at 10 g

Sources checked on 29 October 2026.

What is omega-6?

A family of polyunsaturated fatty acids whose first double bond sits six carbons from the tail of the molecule. Linoleic acid, with 18 carbons and two double bonds, is the parent and nearly all the omega-6 in food; the body lengthens a small share of it into gamma-linolenic, dihomo-gamma-linolenic and arachidonic acids.¹

What is linoleic acid?

The essential omega-6. Humans lack the enzyme that puts a double bond in the omega-6 position, so linoleic acid must be eaten, and EFSA set an adequate intake of 4% of energy, about 9 g a day on 2,000 kcal.¹² The GB register carries two authorised sentences for it: "Linoleic acid contributes to the maintenance of normal blood cholesterol levels" at 10 g a day, and, with ALA, "Essential fatty acids are needed for normal growth and development of children".²

Is omega-6 harmful to the body?

Not on any outcome that has been measured. In 13 cohorts of 310,602 people, those eating the most linoleic acid had 15% fewer coronary events and 21% fewer coronary deaths than those eating the least.⁵ The 30-cohort biomarker analysis ran the same way for total cardiovascular disease, cardiovascular death and ischaemic stroke, and arachidonic acid, the supposed villain, was not associated with higher risk.⁴ Cochrane's 19 randomised trials found all-cause mortality unchanged, a possible reduction in heart attacks, a small long-term fall in total cholesterol and no change in body weight.⁶ The single trial usually quoted against omega-6, the Sydney Diet Heart Study of 1966 to 1973, gave 458 men with heart disease safflower oil and margarine in place of saturated fat and recorded more deaths, 17.6% against 11.8%; it was one small trial, and the larger pooled trials and cohorts above did not find the harm.¹¹

Is omega-3 or omega-6 an anti-inflammatory?

EPA and DHA, the long-chain omega-3s, lower inflammatory markers modestly in trials at gram doses; linoleic acid, the omega-6, does neither harm nor good to them. Linoleic acid is converted to arachidonic acid in small, tightly regulated amounts whatever the intake, and arachidonic acid gives rise to both pro-inflammatory prostaglandins and leukotrienes and to lipoxins, which help resolve inflammation; EPA and DHA give rise to resolvins, protectins and maresins, the mediators that actively switch inflammation off.^{8, 14} Across 68 randomised trials and 4,601 people, EPA and DHA supplements lowered C-reactive protein, interleukin-6 and TNF-alpha by small amounts, more with longer use and less at a BMI over 30.⁹ Raising linoleic acid changed none of those markers in 15 trials.³

Can omega-6 be an anti-inflammatory?

Not measurably, and not a pro-inflammatory either: its derivatives include both anti-inflammatory prostaglandin E1 and pro-inflammatory arachidonic acid products, and in people more linoleic acid leaves the markers where they were.^{3, 8}

How long does omega-3 take to reduce inflammation?

Months, in the trials that saw a change. EPA builds into red blood cell membranes with a half-life of about 28 days and reaches a steady level after roughly six months, which is why longer trials showed larger effects.^{9, 10} A change in blood markers is not what a 250 mg capsule is for: 250 mg is the amount at which the register's heart, brain and vision wordings apply.²

What are the effects of too much omega-6?

None that medicine recognises as a syndrome. The one measurable effect is on omega-3: linoleic acid and ALA share the enzymes that lengthen them, so a very high linoleic acid intake lowers the small share of ALA that becomes EPA.¹ That matters only if ALA is your sole omega-3 source, and the fix is adding EPA and DHA from oily fish or algal oil, not cutting omega-6. Beyond that, oil is energy-dense, so a diet very high in any oil adds weight: a calorie question, not an omega-6 one.

What are the signs of too much omega-6?

None to look for. The symptom checklists online, from acne to joint aches to low mood, are not diagnostic of omega-6 intake; if they bother you, see a GP.

How much omega-6 is healthy?

About 4% of energy, roughly 9 g a day for most adults, is EFSA's adequate intake; the cohorts above found the lowest coronary risk at higher intakes than that.^{5, 12} Figures below are approximate, for typical products.¹⁵

The linoleic acid in a two-capsule serving of a flaxseed-oil 3-6-9 capsule is a fraction of a gram, about a thirtieth of a tablespoon of sunflower oil; it is there because flaxseed oil is about 14% linoleic acid; the ALA is the reason for the capsule, labelled against the 2 g a day at which the register's ALA cholesterol wording applies, and there is no EPA or DHA.^{2, 15} Is it better to take omega-3 or omega 3-6-9 sets the two formats side by side.

Omega-6 foods to avoid?

None, for their omega-6. Seed oils are the usual target, and the evidence above is largely about seed oils: sunflower, corn and soya oils are half to two-thirds linoleic acid, and higher intakes tracked lower, not higher, heart disease.^{4, 5, 15} The swap worth making is saturated fat for unsaturated, the register's own wording for oleic acid and the polyunsaturates.² What foods are high in omega-3, 6 and 9 has the full tables, and the Wellgard omega-3 guide covers the omega-3 side.

What we don't know

Whether raising omega-6 prevents heart attacks: the Cochrane estimate came from seven low-quality trials and did not reach significance.⁶ Whether intakes above the range the cohorts covered carry any risk: no trial has tested them. How far a high linoleic acid intake lowers the EPA made from ALA in people who eat no fish: unmeasured in a real diet.¹ Whether the Sydney result reflects linoleic acid, that margarine or chance.¹¹

Frequently asked questions

What is the best ratio of omega-6 to omega-3?

There is no agreed one. EFSA set separate intakes for each fatty acid and no ratio, the UK Food Standards Agency concluded in 2006 that the ratio is not a useful concept, and every ratio claim submitted to the GB register was rejected as unsubstantiated.^{2, 12, 13} What are the differences between omega-3, 6 and 9 takes the ratio apart.

Does omega-6 cause weight gain?

Not beyond its calories. In the Cochrane trials, raising omega-6 made little or no difference to body mass index.⁶ Does omega-3 make you bigger has more.

Who should avoid omega-6?

Nobody has been identified on the evidence. Advice to avoid omega-6 with diabetes or blood pressure problems has no study behind it: across 83 randomised trials of polyunsaturated fats, raising omega-6 made little or no difference to glucose measures, and the trials could not show an effect on diabetes risk either way.⁷ Anyone on a GP's or dietitian's plan follows it; What are the side effects of omega-3, 6 and 9 lists the label cautions.

Sources

1. Burns-Whitmore B, et al. ALA and linoleic acid in the vegan diet. Nutrients, 2019. Review; no conflicts declared. PubMed 31590264.
2. Great Britain nutrition and health claims (NHC) register. Page last updated 19 May 2026. gov.uk.
3. Johnson GH, Fritsche K. Dietary linoleic acid and markers of inflammation in healthy persons. Journal of the Academy of Nutrition and Dietetics, 2012. Systematic review, 15 randomised trials; funding not stated on PubMed. PubMed 22889633.
4. Marklund M, et al. Biomarkers of dietary omega-6 fatty acids and incident cardiovascular disease and mortality. Circulation, 2019. 30 cohorts, 68,659 people; publicly funded (NIH), two authors with food-manufacturer support. PubMed 30971107.
5. Farvid MS, et al. Dietary linoleic acid and risk of coronary heart disease. Circulation, 2014. Meta-analysis, 13 cohorts, 310,602 people; publicly funded (NIH). PubMed 25161045.
6. Hooper L, et al. Omega-6 fats for the primary and secondary prevention of cardiovascular disease. Cochrane Database of Systematic Reviews, 2018. Cochrane review, 19 trials, 6,461 people, 1 to 8 years; WHO-funded. PubMed 30488422.
7. Brown TJ, et al. Polyunsaturated fats for prevention and treatment of type 2 diabetes. BMJ, 2019. Systematic review, 83 trials of 24 weeks or longer; WHO-funded. PubMed 31434641.
8. Serhan CN. Pro-resolving lipid mediators are leads for resolution physiology. Nature, 2014. Review; publicly funded (NIH). PubMed 24899309.
9. Li K, et al. Marine n-3 fatty acids and CRP, IL-6 and TNF-alpha. PLoS One, 2014. Meta-analysis, 68 trials, 4,601 people; no competing interests. PubMed 24505395.
10. Katan MB, et al. Kinetics of incorporation of dietary fatty acids into tissues. Journal of Lipid Research, 1997. Controlled trial, 58 men, 12 months; funding not stated on PubMed. PubMed 9374124.
11. Ramsden CE, et al. Recovered data from the Sydney Diet Heart Study. BMJ, 2013. Randomised trial, 458 men, 1966 to 1973, plus meta-analysis; publicly funded (NIH). PubMed 23386268.
12. EFSA. Dietary Reference Values for nutrients: summary report, 2017 (fats). Adequate intakes 4% of energy linoleic acid, 0.5% ALA; no ratio set. efsa.europa.eu.
13. Stanley JC, et al. UK Food Standards Agency workshop report: the n-6:n-3 ratio and cardiovascular health. British Journal of Nutrition, 2007. Workshop report; publicly funded (FSA). PubMed 18039412.
14. Plourde M, Cunnane SC. Extremely limited synthesis of long chain polyunsaturates in adults. Applied Physiology, Nutrition, and Metabolism, 2007. Review; funding not stated on PubMed. PubMed 17622276.
15. Public Health England. Composition of foods integrated dataset (CoFID), 2021, fatty acids per 100 g food. Page last updated 19 March 2021. gov.uk. Flaxseed oil: USDA FoodData Central, SR Legacy. fdc.nal.usda.gov.

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This article is general information, not medical advice. If you have been given dietary advice for cholesterol, diabetes or heart disease, follow it and ask your GP or dietitian about fats.