Linoleic acid

Linoleic acid (LA, 18:2 n-6) is a polyunsaturated omega-6 fatty acid with 18 carbon atoms and two double bonds. It is one of only two essential fatty acids. FAO and WHO experts call it indispensable, because humans cannot make it. The other is alpha-linolenic acid.

LA is the main omega-6 fat in the diet, and it comes mostly from vegetable oils, nuts and seeds.

In the body, LA is built into cell membranes and into the lipids that seal the skin. Only a little is turned into arachidonic acid, the parent of the 2-series eicosanoids (signaling molecules). In a tracer study in men, about 0.2% of a labeled LA dose reached arachidonic acid.

Most readers do not know how much this fat has changed in the food supply, or how hard it is argued over. US supply estimates put LA at 2.79% of energy in 1909 and 7.21% in 1999. Soybean oil use rose more than 1,000-fold (modeled from economic data, not measured intake).

Whether that matters is the “seed oil” debate. This page sets out each side at its real evidence level. It covers lipid trials, heart trials, two recovered diet trials, pooled cohort studies and the omega-6 to omega-3 ratio.

Health benefits of linoleic acid

• ★★★Better cholesterol when replacing saturated fatIn 60 trials, cis unsaturated fats in place of saturated fat lowered the ratio of total to HDL cholesterol. Linoleic acid was the main polyunsaturated fat in them, but the trials did not test it alone.
• ★★Mixed results for heart events and deathsPolyunsaturated fat in place of saturated fat cut coronary heart disease by 19% (0.81 times the risk) in a pool of 8 trials. Trials judged well controlled showed no change in heart events or deaths, and a Cochrane review of omega-6 fats found no clear change in deaths.
• ★★No rise in inflammation markersIn 15 trials in healthy people, more linoleic acid did not raise markers such as C-reactive protein or fibrinogen. The reviewers found virtually no randomized evidence that it raises inflammation.
• ★★Conjugated linoleic acid: modest fat lossConjugated linoleic acid (CLA) is a supplement made of forms of linoleic acid, not linoleic acid itself. At 3.2 g a day, fat mass fell 0.09 kg a week more than on placebo across 18 trials.
• ★★Blood arachidonic acid did not change with intakeIn adults on Western-type diets, cutting dietary linoleic acid by up to 90% did not change arachidonic acid in the blood. Raising it up to six-fold did not either.

Foods high in linoleic acid

Linoleic acid is in nuts, seeds and vegetable oils, and our USDA ranking is led by nuts and seeds. Per serving, walnuts lead with 10.8 g in 1 oz (28 g). Pine nuts follow with 9.4 g in 1 oz, and hemp seeds with 8.21 g in 3 tbsp. Soybeans, Brazil nuts, sunflower seeds, pumpkin seeds and pecans come next; the ranking below gives their amounts.

Per 100 g, walnuts (38.1 g), pine nuts (33.2 g) and hemp seeds (27.4 g) lead. Brazil nuts, sunflower seeds and sesame seeds come next. Per 100 kcal, walnuts (5.82 g), hemp seeds (4.95 g) and pine nuts (4.93 g) lead.

Vegetable oils are the biggest sources in practice, but they are not in our ranking. In USDA’s SR Legacy data, per 100 g, linoleic-type safflower oil has 74.6 g of linoleic acid. Linoleic-type sunflower oil (about 65%) has 65.7 g, walnut oil 52.9 g, cottonseed oil 51.5 g and soybean oil 51.0 g. Peanut oil has 32.0 g, canola oil 19.0 g and olive oil 9.76 g.

Butter has 2.73 g and coconut oil 1.68 g. High-oleic types of the same crops are far lower, at 12.7 g for safflower and 3.61 g for sunflower. So the plant on the label does not tell you which fat you are buying.

Our arithmetic for realistic servings: 1 oz of walnuts (10.8 g) gives about 64% of the 17 g US adequate intake for men. It gives 90% of the 12 g for women. An ounce of pine nuts (9.4 g) gives about 55% and 78%. An ounce of sunflower seeds (6.53 g) gives about 38% and 54%.

Heat changes oils. In deep-frying tests, oils rich in linoleic acid gave more 2,4-decadienals, which are aroma compounds. Oils rich in linolenic acid gave the most acrolein, and mainly monounsaturated or saturated oils gave clearly less. That is frying chemistry, not a health result, and we found no trial that compared cold-pressed with refined oils.

Nuts and seeds are not concentrated oils. The Minnesota trial authors caution that results from concentrated oils should not be applied to nuts or other unprocessed foods rich in linoleic acid.

How linoleic acid works

The biochemistry of fatty acids is well established, but what extra linoleic acid does in people is tested in the study cards above.

Four ideas cover most of it. LA is a building block of membranes and the skin barrier, and a small share becomes arachidonic acid. It competes with alpha-linolenic acid for the same enzymes, and the body stores and burns it like other fats. Here is each one, and what has been seen in people.

A small share becomes arachidonic acid

EFSA’s panel describes linoleic acid being elongated and desaturated to arachidonic acid, which goes on to make 2-series eicosanoids. The step is slow in people. In a tracer study in men, about 0.2% of a labeled LA dose reached arachidonic acid. And 12 weeks on 17 g a day of sunflower oil left blood arachidonic acid unchanged.

A systematic review of adult trials agrees. Cutting LA by up to 90% or raising it up to six-fold did not change arachidonic acid in blood phospholipids. Dietary gamma-linolenic acid and arachidonic acid did change it. FAO’s experts add that arachidonic acid is not essential for a healthy adult who gets more than 2.5% of energy as LA, as vegans show.

Arachidonic acid is the reason LA has a bad name. It is the parent of potent signals of inflammation, and drugs that block that pathway are used against inflammation. So many people assume more LA means more inflammation.

A review by Innes and Calder notes that in healthy adults, more LA or arachidonic acid in the diet did not raise many inflammatory markers. It adds that the interaction with omega-3 fats is complex and not properly understood. More on arachidonic acid on its own page.

It competes with alpha-linolenic acid

LA and alpha-linolenic acid use the same enzymes. FAO’s report says excess dietary LA, as with some safflower, sunflower and corn oil, may decrease the formation of DHA from alpha-linolenic acid. The reason is that the delta-6 desaturase is inhibited by excess n-6 substrates. In the tracer study, conversion of each fat varied inversely with the fatty acids of the other family.

In the 22-man crossover trial, 10.5% of energy from LA lowered blood EPA compared with 3.8%. In the UK Biobank cohort, a higher omega-6 to omega-3 ratio went with higher mortality. Whether the ratio itself matters, rather than the amount of each, is the next question.

Does the omega-6 to omega-3 ratio matter?

The ratio idea says the balance of the two families matters more than the amount of each. FAO’s experts found no rationale for a specific n-6 to n-3 ratio, or LA to alpha-linolenic acid ratio. That holds if intakes of each lie within their ranges, and EFSA set no value for it.

A 2006 review found few human trial data to support the ratio and judged it of little value. It favored measures that count EPA and DHA alone.

Observational data point both ways. In UK Biobank a higher plasma ratio went with higher mortality. Yet omega-3 and omega-6 were each linked to lower mortality, omega-3 more strongly.

The trials are small. Very high LA lowered blood EPA in 22 men.

In a migraine trial, raising EPA plus DHA and cutting LA reduced headache days by 2.0 more than the omega-3 change alone. But that diet changed two things at once. Our reading is that getting enough omega-3, from alpha-linolenic acid, EPA and DHA, matters more than hitting a ratio.

It is built into cell membranes and the skin barrier

A review of the skin barrier explains that linoleate-containing acylceramides are essential for barrier function. They sit in the outer skin layer and in the lipid envelope around skin cells. In mice that lack the enzyme Acsl1, which activates linoleic acid, the barrier failed and the pups died as embryos. In mouse liver, a safflower oil diet raised cardiolipin with four LA chains, a lipid of the mitochondrial membrane; this is mouse and lab work.

In people, the clearest sign of how much the body needs LA comes from taking it away. Eight healthy men were given a fat-free diet. LA in the cholesterol esters of their blood fell from 48.8% to 9.8% in 2 weeks, and the deficiency marker eicosatrienoic acid appeared. The chart puts it on one scale.

It is stored and burned like other fats

In a tracer test in men, 41% of a laurate dose was burned within 9 hours, against 13% of stearate. Among 18-carbon fatty acids, linolenate was the most highly oxidized, and linoleate appeared to be somewhat conserved.

LA is also stored. Blood and fat tissue levels of LA reflect diet. That is why cohort studies such as the FORCE pooled analyses use them as markers of intake.

What has been seen in people

Trial diets span a wide range of LA, and so has the food supply over a century. The chart puts the numbers on one scale.

Putting the cards together: LA lowers cholesterol when it replaces saturated fat. It does not raise inflammatory markers or blood arachidonic acid in healthy adults. A very high intake lowers blood EPA compared with a low one.

Pooled cohorts link higher blood LA with fewer cardiovascular deaths and less type 2 diabetes. But the randomized trials that swapped whole fats found no clear gain in deaths or events, and the Sydney trial found harm. The two kinds of evidence answer different questions.

A cohort compares people who differ in many ways. A trial compares diets, usually concentrated oils against animal fats, margarines or nothing. The recovered trials enrolled people with heart disease or people living in institutions. We found no trial that tested linoleic acid alone against a matched diet for heart events.

How much linoleic acid do you need?

Adults need about 12 to 17 g of linoleic acid a day in the US, or 4% of energy in the EU. That is about 9 g on a 2,000 kcal diet (our arithmetic). The US adequate intake is 17 g for men and 12 g for women aged 19 to 50.

EFSA’s adequate intake is 4% of energy for adults, in pregnancy and breastfeeding, and for children from 1 year. FAO and WHO experts say human data are too sparse for a precise requirement, so they give a range. It is an average requirement of 2% of energy and an acceptable range of 2.5 to 9%.

Source	Group	Value	Notes
National Academies (IOM) 2005, adequate intake	Men and women aged 19 to 50	17 g (men), 12 g (women) a day	From age 51 the values are 14 g and 11 g; pregnancy and breastfeeding 13 g. As listed in the intake table above.
National Academies 2005, acceptable range (AMDR)	Children and adults	5 to 10% of energy	The lower end rests on the adequate intake. About 11 to 22 g on 2,000 kcal.
EFSA 2010, adequate intake	Adults, pregnancy, breastfeeding, children from 1 year and infants from 7 months	4% of energy	About 9 g on 2,000 kcal. EFSA set no upper level for total or any n-6 polyunsaturated fat, and no value for the n-6 to n-3 ratio.
FAO/WHO 2010, average requirement and range	Adults	Average requirement 2%, adequate intake 2 to 3%, acceptable range 2.5 to 9% of energy	About 5.6 to 20 g on 2,000 kcal for the range. Infants 6 to 24 months: adequate intake 3.0 to 4.5%, upper limit of the range below 10%.

Those amounts are small next to what many diets supply. US supply estimates put LA at 7.21% of energy in 1999. That is above every adequate intake in the table and inside the National Academies range, though supply is not measured intake. Pregnancy and breastfeeding raise the US adequate intake only a little, to 13 g a day.

Linoleic acid deficiency: signs and who is at risk

Deficiency is rare in people who eat fat. FAO’s report describes signs first recorded in the 1960s: dryness, scaling and thickening of the skin, and poor growth, in infants fed skimmed-milk formula. In that study of 428 infants, intake on the skimmed preparation was 10 mg of LA per kg of body weight a day. On a corn and coconut oil preparation it was 800 mg per kg.

Neonates on fat-free intravenous nutrition also showed signs. In animal and human studies, signs are prevented when LA gives 1 to 2% of energy, according to FAO.

Today the risk sits with people whose fat intake or absorption is very low: fat malabsorption, malnutrition, and intravenous feeding without enough lipid. In eight healthy men on a fat-free diet, blood LA fell sharply within 2 weeks.

A 2025 review looked at deficiency in parenteral nutrition (feeding by vein). It notes that newer multicomponent lipid emulsions contain less LA and alpha-linolenic acid, so dosing matters. It adds that the triene to tetraene ratio (the Holman index) alone can lead to a wrong diagnosis. Its authors include an employee of Baxter Healthcare, which makes lipid emulsions, and consultants for other makers.

Forms of linoleic acid: absorption and effects

Linoleic acid reaches people in whole foods and vegetable oils, in conjugated and downstream forms sold as supplements, on the skin, and by vein. It travels in fat in all of them, and we found no study that compared how well different forms are absorbed.

The honest bottom line is that the heart and metabolism trials tested whole oils and fats. So a result belongs to the oil and the fat it replaced, not to linoleic acid on its own. We found no trial of linoleic acid capsules for any health outcome. Nor did we find any for the popular claim that cold-pressed seed oils are healthier than refined ones.

Where trials exist, the doses are large. Men got 17 g a day of sunflower oil as LA for 12 weeks. Women got 8 g of safflower oil a day for 16 weeks. Other diets gave 10.5% of energy from LA for 4 weeks.

Do not confuse conjugated linoleic acid with linoleic acid. CLA is a group of isomers that acts differently, and its trials are about fat loss.

Form	What it is	What studies show	Source
Nuts and seeds	LA inside whole foods, with their other fats and nutrients	Walnuts, pine nuts and sunflower seeds lead our ranking. The Minnesota authors caution that results from concentrated oils should not be generalized to nuts or other unprocessed foods. We found no trial that compared LA from nuts with LA from oil for heart events.	1, 2
Vegetable oils rich in LA (safflower, sunflower, soybean, corn)	Triglyceride oils, up to 74.6 g of LA per 100 g	Used in the diet-heart trials: safflower oil and margarine in Sydney, corn oil in Minnesota. Sunflower oil muffins gave less liver fat than palm oil in a 7-week overfeeding trial, and vegetable n-6 fat gave less liver fat than butter in a 10-week trial. Safflower oil at 8 g a day lowered trunk fat and fasting glucose in women with type 2 diabetes.	1, 3, 2, 4, 5, 6
High-oleic versions of the same oils	Bred or processed to hold mostly oleic acid; 12.7 g of LA per 100 g in safflower, 3.61 g in sunflower	LDL from people on an oleate-rich diet was less easily oxidized in a test tube than LDL from a linoleate-rich diet, but that is not a heart outcome. We found no trial that compared high-linoleic with high-oleic oils for heart events.	1, 8
Conjugated linoleic acid (CLA) supplements	A group of LA isomers sold for weight loss, a different compound	About 3.2 g a day gave a modest loss of fat mass, 0.09 kg a week more than placebo, in 18 trials. In a crossover trial, CLA lowered BMI while safflower oil did not.	7, 6
Linoleic acid on the skin	Topical LA or sunflower-seed oil	Topical LA cut the size of acne microcomedones by almost 25% in a month. Two 1970s reports describe correcting essential fatty acid deficiency in people by putting sunflower-seed oil on the skin. In mice, skin barrier lipids need LA.	9, 10, 11, 12
Arachidonic acid and gamma-linolenic acid	Downstream omega-6 fats	Dietary arachidonic acid and gamma-linolenic acid raised blood arachidonic acid in adult trials, whereas linoleic acid did not. See the page on arachidonic acid.	13
Intravenous lipid emulsions	LA given by vein to people who cannot eat	Products differ in LA content, and newer multicomponent emulsions hold less, so dosing matters to prevent deficiency.	14
Heated or reused oils	LA-rich oil after frying	Frying LA-rich oil made more 2,4-decadienals in a lab test. We found no human trial of heated oils and health outcomes.	15

Here are the form-specific studies, strongest evidence first, 5 in all.

Is linoleic acid safe? Limits and who should watch it

Linoleic acid from food is not a safety concern for healthy people at usual intakes, and no official upper limit exists. EFSA’s 2010 opinion set no upper level for total or any n-6 polyunsaturated fat.

The FAO and WHO experts put the top of their acceptable range at 9% of energy for LA and 11% for all polyunsaturated fat. Their reason is that experimental studies suggest lipid peroxidation may rise above 11%, particularly when vitamin E (tocopherol) intake is low. The National Academies range tops out at 10% of energy. These are range limits, not toxicity thresholds.

• Heart disease and death. The trial evidence is mixed. The Cochrane review found little or no difference in death or cardiovascular events (1.00 and 0.97 times the risk). In the recovered Sydney trial, deaths were higher on safflower oil in men with heart disease (1.62 times). The Minnesota diet held almost twice the LA of the average American diet. People with heart disease should follow their doctor’s dietary advice.
• Inflammation and blood fats. In 15 trials in healthy people, more LA did not raise inflammatory markers. A high n-6 diet showed no signs of inflammation or oxidative stress in 61 adults with abdominal obesity. In a 22-man crossover trial, 10.5% of energy from LA lowered blood EPA compared with 3.8%. So people who eat little fish should watch their omega-3 intake.
• Heated oils. In frying tests, LA-rich oils made more 2,4-decadienals, and oils rich in linolenic acid gave the most acrolein. We found no human trial of heated or reused oils and health outcomes.
• Fat malabsorption and intravenous feeding. People who cannot absorb fat, or who depend on parenteral nutrition, can develop essential fatty acid deficiency. Some lipid emulsions are low in LA, and the care team sets the dose.

How to get enough linoleic acid

• Best foods. Walnuts give 10.8 g in 1 oz, pine nuts 9.4 g and sunflower seeds 6.53 g. An ounce of walnuts covers about 64% of the US adequate intake for men and 90% for women (our arithmetic).
• Swap rather than add. The cholesterol evidence is about replacing saturated fat with polyunsaturated fat. The EU claim assumes 10 g of LA a day, from food with at least 1.5 g per 100 g and per 100 kcal. The 2026 review found fewer nonfatal heart attacks when polyunsaturated fat replaced saturated fat (0.75 times the risk).
• Keep omega-3 in the mix. Add alpha-linolenic acid from walnuts, flaxseed and similar foods, and EPA and DHA from fish. The trial with 10.5% of energy from LA lowered blood EPA.

History of linoleic acid

In 1929, George and Mildred Burr at the University of Minnesota fed rats a diet that excluded fat more strictly than before. The rats developed scaly skin, inflamed tails and kidney damage, and died within three or four months; as little as three drops of lard helped.

In 1930 the Burrs showed that linoleic acid was the cure, and coined the phrase “essential fatty acids”. The idea was disputed at first. A Yale group in the same issue of the journal argued that the value of fat lay in its vitamins and calories.

For people it took until the 1960s. Dryness, scaling and growth faltering were recorded in infants fed skimmed-milk formula (Hansen and colleagues, 1963, 428 infants), according to FAO. They were also seen in neonates given fat-free intravenous nutrition. In 1975, Wene and colleagues showed that healthy men develop biochemical deficiency within 2 weeks on a fat-free diet.

The seed oil story is more recent. Soybean oil use in the US rose more than 1,000-fold between 1909 and 1999. LA climbed from 2.79% to 7.21% of energy on supply estimates.

Two trials of the 1960s and 70s had tested whether replacing saturated fat with LA-rich oil prevents heart disease. They were the Sydney Diet Heart Study (1966 to 73) and the Minnesota Coronary Experiment (1968 to 73), whose co-principal investigators included Ancel Keys. The authors who recovered the unpublished data say the results of both had not been fully reported.

They published the Sydney data in 2013 and the Minnesota data in 2016, both without benefit, and Sydney with higher deaths. Skeaff and Mann answered in a commentary that the diet-heart hypothesis is unaffected by the Minnesota data.

The pooled cohort work came back with the opposite signal. In 2019, the FORCE consortium reported that higher blood and tissue LA went with lower cardiovascular risk across 30 studies. The Cochrane review of omega-6 fats, updated in 2018, found no clear effect of more omega-6 on death or events. Both sides keep their evidence, and neither design can settle the question alone.

Frequently asked questions about linoleic acid

Are seed oils and linoleic acid bad for you?

The evidence does not show harm at usual intakes, but it does not prove a heart benefit either. In 30 cohorts with 68,659 people, higher blood linoleic acid went with lower cardiovascular death (0.78 times the risk). The Cochrane review of 19 trials found little or no difference in death (1.00) or cardiovascular events (0.97).

The recovered Sydney trial found more deaths on safflower oil (1.62 times the risk), and the Minnesota trial found no benefit despite lower cholesterol. Cohorts cannot show cause, so the debate is open.

Does linoleic acid cause inflammation?

Not in healthy people in trials. A review of 15 randomized trials found no significant change in C-reactive protein, fibrinogen, cytokines or other markers. In 61 adults with abdominal obesity, a high n-6 diet showed no signs of inflammation.

Arachidonic acid, made from LA, is the parent of inflammatory signals. But blood arachidonic acid did not change when LA was cut by up to 90% or raised up to six-fold.

How much linoleic acid per day?

The US adequate intake is 17 g for men and 12 g for women aged 19 to 50. EFSA’s is 4% of energy, about 9 g on 2,000 kcal (our arithmetic). The US acceptable range is 5 to 10% of energy and the FAO/WHO range is 2.5 to 9%.

In animal and human studies, deficiency signs are prevented at 1 to 2% of energy. One ounce of walnuts gives 10.8 g.

What is the difference between linoleic acid and linolenic acid?

Linoleic acid is an omega-6 fat with two double bonds (18:2 n-6). Alpha-linolenic acid is an omega-3 fat with three (18:3 n-3). Humans cannot make either, so both are essential, and they use the same enzymes. In a tracer study, conversion of each varied inversely with the fatty acids of the other family.

See our page on alpha-linolenic acid.

Does the omega-6 to omega-3 ratio matter?

It matters less than the amounts of each. FAO’s experts found no rationale for a specific ratio if intakes lie within their ranges, and EFSA set no value for it. A 2006 review judged the ratio of little value and favored measures of EPA and DHA.

In UK Biobank, a higher plasma ratio went with 26% higher total mortality. Yet omega-3 and omega-6 were each linked to lower mortality, omega-3 more strongly. Diets with 10.5% of energy from LA lowered blood EPA compared with 3.8%.

Which foods are highest in linoleic acid?

Per serving, walnuts lead our USDA ranking with 10.8 g in 1 oz. Pine nuts follow (9.4 g), then hemp seeds (8.21 g in 3 tbsp) and soybeans (7.68 g in 1 cup).

Per 100 g, USDA lists 74.6 g for linoleic-type safflower oil and 65.7 g for linoleic-type sunflower oil. That compares with 9.76 g for olive oil and 2.73 g for butter. High-oleic safflower and sunflower oils have only 12.7 g and 3.61 g.

Is linoleic acid good for skin?

It is needed for the skin barrier, and deficiency dries and scales the skin. In infants on skimmed-milk formula, FAO lists dryness, desquamation and thickening of the skin. We found no trial showing extra dietary LA improves skin in people who already get enough.

Topical linoleic acid cut acne microcomedone size by almost 25% in a month-long trial in mild acne. But it was applied to the skin, not eaten.

Is conjugated linoleic acid (CLA) the same as linoleic acid?

No. CLA is a group of isomers of linoleic acid sold as a supplement for fat loss. A meta-analysis of 18 trials found about 3.2 g a day gave a modest fat loss, 0.09 kg a week more than placebo. In one crossover trial, CLA lowered BMI but 8 g a day of safflower oil did not.