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Omega-6 fatty acids

Synonyms/Common Names/Related Substances:

  • 4-hydroxynonenal, 18:2 omega-6, 18:2n-6, 18:3 omega-6, 18:3n-6, 20:2 omega-6, 20:2n-6, 20:3 omega-6, 20:3n-6, 20:4 omega-6, 20:4n-6, 22:2 omega-6, 22:2n-6, 22:4 omega-6, 22:4n-6, 22:5 omega-6, 22:5n-6, adrenic acid, arachidonic acid, calendic acid, dihomo-gamma-linolenic acid, docosadienoic acid, docosapentaenoic acid, eicosadienoic acid, eicosanoids, gamma-linolenic acid, hexanal, linoleic acid, n-6, omega-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 both endogenous and supplemented 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.

Clinical Bottom Line/Effectiveness

Brief Background:

  • Omega-6 fatty acids are a family of polyunsaturated fatty acids with the first carbon-carbon double bond in the sixth carbon position (unlike omega-3 fatty acids, where the first carbon-carbon double bond is in the third position). Fatty acids in this family include the essential fatty acid linoleic acid (18:2n-6), gamma-linolenic acid (18:3n-6; found in oils such as evening primrose oil and borage oil and used for its supposed anti-inflammatory benefits), and arachidonic acid (20:4n-6; found mainly in animal fats and fish). Linoleic acid is converted by subsequent desaturation (increased number of double bonds) and elongation (addition of carbons) to other longer-chain and more unsaturated fatty acids, such as gamma-linolenic acid and arachidonic acid. Some omega-6 fatty acids, for example arachidonic acid, are converted to eicosanoids, such as prostaglandins, leukotrienes, and thromboxanes. These eicosanoids are active in every tissue of the body. Production of eicosanoids may lead to both positive (immune function and wound healing) and negative (excess blood coagulation, platelet aggregation, and inflammation) effects. Arachidonic acid is also found in the brain and is essential for brain function, growth, and development. As such, it is found in high levels in breast milk and has recently been added to infant formulas along with the fatty acid docosahexaenoic acid.
  • Raman spectroscopy is one method of determining omega-6 fatty acids in the fat of animals (1), but other methods have been examined (2;3). These methods show omega-6 fatty acids are present in both land and sea animal adipose tissue (1;2;3;4). In rainbow trout, arachidonic acid was found in high concentrations in phophosphatidylinositol (PI) (5). In fish caught off the northwest coast of Australia, all species contained high levels of omega-6 fatty acids, mainly arachidonic acid, but also docosatetraenoic and docosapentaenoic acids (omega-6) (6).
  • Deficiencies in omega-6 fatty acid status may lead to reduced growth, skin conditions, infertility, a reduced immune response, and other negative effects. However, omega-6 fatty acid deficiencies are extremely rare. 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. For this reason, omega-6 fatty acids have recently received a bad reputation, especially when compared with omega-3 fatty acids, which are found in lower dietary levels. 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 and coordination disorders, as well as eye disorders. Also, in human research, levels of certain omega-6 fatty acids in the plasma were 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 (7).

Dosing/Toxicology

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Precautions/Contraindications

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Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. 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.

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Mechanism of Action

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History

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Evidence Table

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Evidence Discussion

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Products Studied

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Author Information

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References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

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The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.