Supplement
Omega-6 fatty acids are essential fats, such as linoleic acid, that the body cannot make and uses to build cell membranes and signalling molecules involved in inflammation. Most people look at them for heart health, and trials found that replacing saturated fat with linoleic acid lowered LDL cholesterol, with higher intake linked to fewer cardiovascular events. The evidence is moderate, though some cholesterol findings came from cell studies, and the benefits applied when omega-6 replaced saturated fat.
Sources: PMID 12848277; PMID 9566835
- Updated
- How we grade
- 24 studies cited
- Best evidence
- Grade B
- Conditions studied
- 4
- Outcomes
- 9
- Graded outcomes
- 0315
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| LDL Cholesterol Multiple RCTs demonstrate that replacing saturated fat with linoleic acid significantly reduces LDL cholesterol. The AHA recommends 5-10% of calories from omega-6 PUFAs based on consistent trial evidence. An in vitro study confirmed LA modulates cholesterol metabolism in intestinal epithelial cell models. | Improves (the measure goes down) | Moderate effect | 2 studies | |||
Studies that measured ldl cholesterol | ||||||
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Cardiovascular Disease Risk Epidemiological studies and RCTs demonstrate that higher dietary linoleic acid intake, when replacing saturated fat, is associated with reduced cardiovascular events. Contrary to the popular narrative, controlled human trials show omega-6 (LA) does not increase systemic inflammatory markers relevant to atherosclerosis. | Improves (the measure goes down) | Moderate effect | 2 studies | |||
Studies that measured cardiovascular disease risk
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Arthritis (Multiple Kinds)
- Rheumatoid Arthritis Symptoms: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Rheumatoid Arthritis Symptoms Multiple human clinical trials demonstrate that GLA (gamma-linolenic acid) supplementation from evening primrose or borage oil reduces joint pain, swelling, and morning stiffness in rheumatoid arthritis. GLA is converted to DGLA and subsequently to anti-inflammatory series-1 prostaglandins, providing a mechanistic basis for these effects. | Improves (the measure goes down) | Moderate effect | 2 studies | |||
Studies that measured rheumatoid arthritis symptoms | ||||||
General
- Atopic Dermatitis Symptoms: improves
- Tumor Cell Growth (GLA): changes; see studies
- Brain Fatty Acid Composition: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Atopic Dermatitis Symptoms A clinical trial found that dietary hempseed oil (rich in LA and GLA) improved atopic dermatitis symptoms. Evening primrose oil supplementation reduced uremic skin symptoms in hemodialysis patients over six weeks. Altered n-6 fatty acid profiles in plasma lipids have been observed in children with atopic conditions, suggesting a role in skin barrier dysfunction. | Improves (the measure goes down) | Small effect | 2 studies | |||
| Tumor Cell Growth (GLA) Multiple preclinical studies demonstrate GLA has tumoricidal activity against glioma, breast, lung, and prostate cancer cells via free radical generation and lipid peroxidation. One small clinical study used intratumoral GLA injection in human gliomas. GLA selectively inhibits oncogenic fatty acid synthase (OA-519) in breast cancer models and upregulates the tumor suppressor maspin. | Changes; see studies | Moderate effect | 8 studies | |||
Studies that measured tumor cell growth (gla)
| ||||||
| Brain Fatty Acid Composition In artificially reared rats, formula supplementation with GLA and DHA altered brain fatty acid composition favorably. Reviews emphasize that omega-6 fatty acids are essential for brain development and discuss their role in cognitive function and neurological disorders including multiple sclerosis. | Improves (the measure goes up) | Small effect | 3 studies | |||
Studies that measured brain fatty acid composition
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| Diabetic Neuropathy Evening primrose oil supplementation improved serum fatty acid profiles and plasma prostaglandin levels in children with diabetes mellitus. In streptozotocin-diabetic rats, arachidonic acid-rich oil supplementation improved nerve conduction velocity and endoneurial blood flow, suggesting potential neuroprotective effects. | Improves (the measure goes up) | Small effect | 2 studies | |||
Studies that measured diabetic neuropathy
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| Pulmonary Fibrosis In a hamster model, a GLA-containing diet significantly attenuated bleomycin-induced lung fibrosis, suggesting anti-fibrotic properties of gamma-linolenic acid through modulation of inflammatory mediators in pulmonary tissue. | Improves (the measure goes down) | Moderate effect | 1 study | |||
Studies that measured pulmonary fibrosis | ||||||
Autoimmune Health
- Immune Function: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Immune Function Animal studies demonstrate dose-dependent modulation of spleen lymphocyte function by dietary GLA. Cyclic vs continuous enteral feeding with GLA altered immune cell phospholipid fatty acid composition in rat lung and liver. Reviews highlight the importance of n-6/n-3 balance in immune regulation, autoimmunity, and the essentiality of n-6 for normal immune function. | Improves (the measure goes up) | Small effect | 4 studies | |||
Studies that measured immune function
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Key findings
- LDL CholesterolImproves (the measure goes down)
- Cardiovascular Disease RiskImproves (the measure goes down)
- Rheumatoid Arthritis SymptomsImproves (the measure goes down)
Shop the evidence-backed picks
Third-party tested Omega-6 Fatty Acids products, in the forms the graded studies used where we can match them.
- Grade B
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Studies cited
24 studies from PubMed
- Control of Fatty Acid Intake and the Role of Essential Fatty Acids in Cognitive Function and Neurological Disorders.
- Co-supplementation of healthy women with fish oil and evening primrose oil increases plasma docosahexaenoic acid, gamma-linolenic acid and dihomo-gamma-linolenic acid levels without reducing arachidonic acid concentrations.
- Polyunsaturated fatty acids in the pathogenesis and treatment of multiple sclerosis.
- Overexpression and hyperactivity of breast cancer-associated fatty acid synthase (oncogenic antigen-519) is insensitive to normal arachidonic fatty acid-induced suppression in lipogenic tissues but it is selectively inhibited by tumoricidal alpha-linolenic and gamma-linolenic fatty acids.
- Fatty acids, the immune response, and autoimmunity: a question of n-6 essentiality and the balance between n-6 and n-3.
- Modulation of cholesterol concentration in Caco-2 cells by incubation with different n-6 fatty acids.
- Effects of oral supplementation with evening primrose oil for six weeks on plasma essential fatty acids and uremic skin symptoms in hemodialysis patients.
- Dose-dependent effects of dietary gamma-linolenic acid on rat spleen lymphocyte functions.
- Effects of gamma-linolenic acid and docosahexaenoic acid in formulae on brain fatty acid composition in artificially reared rats.
- Importance of dietary gamma-linolenic acid in human health and nutrition.
- The effects of n-6 polyunsaturated fatty acids on the expression of nm-23 in human cancer cells.
- Effects of supplementation with unsaturated fatty acids on plasma and membrane lipid composition and platelet function in patients with cirrhosis and defective aggregation.
- Effect of n-6 polyunsaturated fatty acids on growth and lipid composition of neoplastic and non-neoplastic canine prostate epithelial cell cultures.
- Gamma linolenic acid regulates expression of maspin and the motility of cancer cells.
- Effects of dietary supplementation with arachidonic acid rich oils on nerve conduction and blood flow in streptozotocin-diabetic rats.
- gamma-Linolenic acid-containing diet attenuates bleomycin-induced lung fibrosis in hamsters.
- Cyclic vs continuous enteral feeding with omega-3 and gamma-linolenic fatty acids: effects on modulation of phospholipid fatty acids in rat lung and liver immune cells.
- (n-6)-Fatty acids in plasma lipids of children with atopic bronchial asthma.
- Effects of linoleic acid and gamma-linolenic acid on the growth and metastasis of a human breast cancer cell line in nude mice and on its growth and invasive capacity in vitro.
- Effect of dietary supplementation with gamma-linolenic acid on the growth of a human lung carcinoma implanted in nude mice.
- Effects of dietary alpha- and gamma-linolenic acids on liver fatty acids, lipid metabolism, and survival in sepsis.
- Intratumoral gamma-linoleic acid therapy of human gliomas.
- Tumoricidal action of cis-unsaturated fatty acids and their relationship to free radicals and lipid peroxidation.
- Fatty acid and prostaglandin metabolism in children with diabetes mellitus. II. The effect of evening primrose oil supplementation on serum fatty acid and plasma prostaglandin levels.