Omega-6 fatty acids

Related Terms

Adrenic acid, arachidonic acid, calendic acid, dihomo-gamma-linolenic acid, docosadienoic acid, docosapentaenoic acid, eicosadienoic acid, eicosanoids, gamma-linolenic acid, hexanal, hydroxynonenal, linoleic acid, n-6.
Note: This monograph discusses omega-6 fatty acids in general and is based on the literature search term omega-6 fatty acids. The effects of omega-6 fatty acids within the body as well as supplemental omega-6 fatty acids are included in the monograph. The essential fatty acid linoleic acid (18:2n-6) is not discussed in detail in this monograph. Oils rich in omega-6 fatty acids (e.g., corn oil) are not specifically discussed in this monograph. Oils rich in gamma-linolenic acid (18:3n-6), such as evening primrose oil, are not specifically discussed in this monograph.

Background

Omega-6 fatty acids are a family of polyunsaturated fatty acids including linoleic acid, gamma-linolenic acid, and arachidonic acid. In North America, omega-6 fatty acids are found in adequate amounts in the diet, as they are found in salad dressings, margarines, and other plant and animal oil sources. The negative reputation of omega-6 fatty acids is likely based on inadequate intakes of omega-3 fatty acids and not excessive omega-6 fatty acid intakes.
Although not commonly used alone as dietary supplements, there is some evidence in support of omega-6 fatty acids, in combination with omega-3 fatty acids, for attention-deficit hyperactivity disorder (ADHD) and coordination disorders, as well as eye disorders. Also, levels of certain omega-6 fatty acids in the blood were found to be lower in multiple sclerosis patients vs. healthy controls with similar dietary intakes. However, there is a lack of evidence in support of supplementation in multiple sclerosis patients.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


Both omega-3 (mainly docosahexaenoic acid) and omega-6 (mainly gamma-linolenic acid) fatty acids have been studied in patients with ADHD. Further research is needed before conclusions may be drawn.

 C


Both omega-3 (mainly docosahexaenoic acid) and omega-6 (mainly gamma-linolenic acid) fatty acids have been studied in patients with ADHD. Further research is needed before conclusions may be drawn.

 C


Both omega-3 (mainly docosahexaenoic acid) and omega-6 (mainly gamma-linolenic acid) fatty acids have been studied in patients with developmental disorders and ADHD. Further research is needed.

 C


Both omega-3 (mainly docosahexaenoic acid) and omega-6 (mainly gamma-linolenic acid) fatty acids have been studied in patients with developmental disorders and ADHD. Further research is needed.

 C


Limited research suggests that a supplement containing omega-6 fatty acids may improve the symptoms of meibomian gland dysfunction. However, it is not clear if the supplement also contained other agents. Additional research on the use of omega-6 fatty acids alone is needed before conclusions may be drawn.

 C


Limited research suggests that a supplement containing omega-6 fatty acids may improve the symptoms of meibomian gland dysfunction. However, it is not clear if the supplement also contained other agents. Additional research on the use of omega-6 fatty acids alone is needed before conclusions may be drawn.

 C


Limited research suggests that a supplement containing omega-6 fatty acids may improve the results of photorefractive keratectomy (a type of laser eye surgery). However, it is not clear if the supplement also contained other agents. Additional research on the use of omega-6 fatty acids alone is needed before conclusions may be drawn.

 C


Limited research suggests that a supplement containing omega-6 fatty acids may improve the results of photorefractive keratectomy (a type of laser eye surgery). However, it is not clear if the supplement also contained other agents. Additional research on the use of omega-6 fatty acids alone is needed before conclusions may be drawn.

 C


Lower levels of certain omega-6 fatty acids were detected in the plasma of multiple sclerosis patients than in healthy controls. Additional research is required before conclusions may be drawn.

 C


Lower levels of certain omega-6 fatty acids were detected in the plasma of multiple sclerosis patients than in healthy controls. Additional research is required before conclusions may be drawn.

 C
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Dosing

Adults (18 years and older)
For eye disorders (meibomian gland dysfunction), 28.5 milligrams of linoleic acid and 15 milligrams of gamma-linolenic acid have been taken by mouth daily for 180 days in MedilarT tablets (a combination product), which also contain omega-3 fatty acids, vitamin E, vitamin C, vitamin B6, vitamin B12, and zinc.
For multiple sclerosis, 11-23 grams of linoleic acid has been taken by mouth daily. Information on the duration of treatment was lacking.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Interactions

Interactions with Drugs
Omega-6 fatty acids may cause insulin resistance and affect blood sugar levels. Caution is advised when using medications that may also affect blood sugar. Patients taking insulin or drugs for diabetes by mouth should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.
Omega-6 fatty acids may increase the risk of bleeding when taken with drugs that increase the risk of bleeding. Some examples include aspirin, anticoagulants (blood thinners) such as warfarin (Coumadin?) or heparin, antiplatelet drugs such as clopidogrel (Plavix?), and nonsteroidal anti-inflammatory drugs such as ibuprofen (Motrin?, Advil?) or naproxen (Naprosyn?, Aleve?).
Omega-6 fatty acids may cause high blood pressure. Caution is advised in patients taking drugs that lower blood pressure.
Omega-6 fatty acids may also interact with agents that affect the immune system, agents used for the heart, antiasthmatics, anticancer agents, anti-inflammatory agents, cholesterol-lowering agents, clofibric acid, drugs used for osteoporosis, estrogen and progestin combinations, gentamicin, iron, neurologic agents, norepinephrine, psychiatric agents, or thyroid hormones.

Attribution

This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

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