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Omega-6 Fatty Acids

Uses

Omega-6 fatty acids are polyunsaturated fatty acids that perform essential functions in the human body. The most abundant member of this family in food and in the body is linoleic acid. Other members include gamma-linolenic acid and arachidonic acid. Linoleic acid is considered an essential fatty acid since it cannot be synthesized by the body. However, other members of the omega-6 family can be made from linoleic acid.

Omega-6 fatty acids have numerous important roles in the body.1 They contribute to the structure and function of cell membranes and play a part in the regulation of gene activity inside the cell. Arachidonic acid is especially abundant in the brain, and may be important for normal brain development of the fetus and infant. Both arachidonic acid and gamma-linolenic acid can be converted to prostaglandins and related substances that affect inflammation, blood clotting, smooth muscle tone, and many other body activities.

What Are Star Ratings?

This supplement has been used in connection with the following health conditions:

Used forWhy
3 Stars
Atherosclerosis
Follow label instructions
Though the effect has not been studied with supplements, an analysis of several controlled trials found that replacing saturated fats in the diet with omega-6 fats reduces the risk of coronary heart disease.
A diet high in omega-6 fatty acids, found in certain vegetable oils such as corn, safflower, grapeseed, and sunflower oil, and in other foods such as nuts and seeds, appears to protect against atherosclerosis. Higher dietary intake or high body levels of omega-6 fatty acids has been associated with reduced coronary heart disease risk in numerous preliminary studies, and an analysis of several controlled trials found that replacing saturated fats in the diet with omega-6 fats reduces the risk of coronary heart disease by an average of 24%.

How It Works

How to Use It

The Adequate Intake of linoleic acid recommended for adults by the Institute of Medicine is 11 to 17 grams per day depending on age and gender, which is equivalent to 5 to 6% of total daily calories.2 Other authorities recommend up to 10% of total daily calories be consumed as omega-6 fatty acids, primarily for the purpose of preventing cardiovascular disease.3, 4

Arachidonic acid is an omega-6 fatty acid found in animal fats that the body uses to make inflammatory substances. In a controlled study,5 people with rheumatoid arthritis were instructed to reduce their arachidonic acid intake to less than 90 mg per day by eating minimal amounts of meat, no egg yolks, and only low-fat milk products. Compared with a group following a typical Western diet, the low arachidonic acid diet led to a 14% reduction in the number of tender and swollen joints. A second part of this study also found that the anti-inflammatory benefits of fish oil were significantly better when combined with the low arachidonic acid diet.

Where to Find It

Most food containing fats or oils contains at least some omega-6 fatty acids. Highest amounts of linoleic acid are found in certain vegetable oils such as corn, safflower, grapeseed, and sunflower oil, and in other foods such as nuts and seeds. Arachidonic acid is found in small amounts in meat, fish (especially farmed tilapia), milk products, and egg yolk. Gamma-linolenic acid is not found in foods but is high in supplements such as borage oil, evening primrose oil, and black currant seed oil.

Possible Deficiencies

Typical Western diets are abundant in omega-6 fatty acids, so deficiencies usually occur only in special situations, such as starvation and diseases that affect fat absorption.

Interactions

Interactions with Supplements, Foods, & Other Compounds

Linoleic acid competes with alpha-linolenic acid, an omega-3 fatty acid, for enzymes that convert simple polyunsaturated fatty acids into more complex ones. Since complex omega-3 fatty acids such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are associated with heart disease prevention, reduced inflammation, and other health benefits, some authorities have argued that the high amounts of linoleic acid in the typical Western diet are detrimental to health because they can reduce the body’s production of EPA and DHA.6 While most controlled research suggests that dietary linoleic acid has some influence on the production of EPA in the body,7, 8, 9 conversion of alpha-linolenic acid into more complex omega-3 fatty acids is limited for other reasons,10, 11, 12 so that achieving adequate levels of EPA and DHA depends mostly on consuming oily fish and fish oils, which are good sources of these complex omega-3 fatty acids.13 Furthermore, higher dietary intake or high body levels of omega-6 fatty acids, most of which is linoleic acid, has been associated with reduced coronary heart disease risk in numerous preliminary studies, and with no effect on other diseases such as stroke or cancer.14

A diet high in polyunsaturated fats such as the omega-6 fatty acids increases vitamin E requirements. Based on available evidence, at least 0.6 mg (0.9 IU) of vitamin E is needed for every gram of polyunsaturated fat consumed.15

Interactions with Medicines

Certain medicines interact with this supplement.

What Are Drug Interactions
Types of interactions:BeneficialAdverseCheck

Replenish Depleted Nutrients

  • none

Reduce Side Effects

  • none

Support Medicine

  • Anastrozole

    GLA found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Bicalutamide

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Estramustine

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Leuprolide

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Megestrol

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Nilutamide

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Tamoxifen

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Toremifene

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

  • Triptorelin Pamoate

    Gamma-linolenic acid (GLA), found in evening primrose and borage oils, may enhance the therapeutic effects of tamoxifen. A small group of breast cancer patients took 2.8 g of oral GLA per day in addition to tamoxifen, in a preliminary trial. Another group of breast cancer patients took tamoxifen alone. Those taking the GLA-tamoxifen combination appeared to have a better clinical response than did those taking tamoxifen alone. However, the results of this preliminary research are far from conclusive and need to be confirmed in a larger, more definitive trial.

Reduces Effectiveness

  • none

Potential Negative Interaction

  • none

Explanation Required

  • none

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers’ package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a supplement with your doctor or pharmacist.

Side Effects

Side Effects

One of the omega-6 fatty acids, arachidonic acid, can be used by the body to make substances that are inflammatory, increase blood clotting, or constrict blood vessels.16, 17 A controlled study showed that a low arachidonic acid diet provided some relief to people with rheumatoid arthritis, an inflammatory disease.18 However, studies of the effect of arachidonic acid on heart disease risk factors have found either no effect or a beneficial effect of higher arachidonic acid intake.19 More research is needed to determine the effects of arachidonic acid on different diseases.

Since arachidonic acid can be made from other omega-6 fatty acids, some authorities have theorized that reducing the consumption of all omega-6 fatty acids might help prevent or relieve inflammatory diseases and other conditions, such as heart disease, that are associated with certain arachidonic acid byproducts.20, 21 However, production of arachidonic acid from other omega-6 fatty acids appears to be quite limited.22 Also, gamma-linolenic acid is an omega-6 fatty acid that the body can use to make anti-inflammatory substances.23, 24 Finally, preliminary studies have found that blood measures of inflammation are actually lower in people with higher omega-6 intake,25, 26 and preliminary and controlled studies suggest that high omega-6 intake prevents cardiovascular disease.27 Overall, there appears to be benefit, not risk, in consuming omega-6 fatty acids other than arachidonic acid.

References

1. Jones PJ, Kubow K. Lipids, sterols, and their metabolites. In Shils ME, Shike, M, Ross AC, et al, eds. Modern Nutrition in Health and Disease, 10th edition. Philadelphia: Lippincott Williams & Wilkins, 2005:110-114.

2. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Washington, DC: National Academies Press; 2005:464.

3. Dietary guidelines for Americans: The report of the Dietary Guidelines Advisory Committee on Dietary Guidelines for Americans, 2005.Department of Health and Human Services [cited 2010 Feb 16]. Available from URL: www.health.gov/dietaryguidelines/dga2005/report/default.htm.

4. National Heart, Lung, and Blood Institute. Third Report of the Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) [cited 2010 Feb 16]. Available from URL: www.nhlbi.nih.gov/guidelines/cholesterol/index.htm.

5. Adam O, Beringer C, Kless T, et al. Anti-inflammatory effects of a low arachidonic acid diet and fish oil in patients with rheumatoid arthritis. Rheumatol Int 2003;23:27-36.

6. Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med (Maywood) 2008;233:674-88 [review].

7. Burdge GC, Calder PC. Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults. Reprod Nutr Dev 2005;45:581-97 [review].

8. Liou YA, King DJ, Zibrik D, Innis SM. Decreasing linoleic acid with constant alpha-linolenic acid in dietary fats increases (n-3) eicosapentaenoic acid in plasma phospholipids in healthy men. J Nutr 2007;137:945-52.

9. Friesen RW, Innis SM. Linoleic acid is associated with lower long-chain n-6 and n-3 fatty acids in red blood cell lipids of Canadian pregnant women. Am J Clin Nutr 2010;91:23-31.

10. Brenna JT. Efficiency of conversion of alpha-linolenic acid to long chain n-3 fatty acids in man. Curr Opin Clin Nutr Metab Care 2002;5:127-32 [review].

11. Goyens PL, Spilker ME, Zock PL, et al. Compartmental modeling to quantify alpha-linolenic acid conversion after longer term intake of multiple tracer boluses. J Lipid Res 2005;46:1474-83.

12. Hussein N, Ah-Sing E, Wilkinson P, et al. Long-chain conversion of [13C] linoleic acid and alpha-linolenic acid in response to marked changes in their dietary intake in men. J Lipid Res 2005;46:269-80.

13. Burdge GC, Calder PC. Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults. Reprod Nutr Dev 2005;45:581-97 [review].

14. Harris WS, Mozaffarian D, Rimm E, et al. Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation 2009;119:902-7 [review].

15. Valk EE, Hornstra G. Relationship between vitamin E requirement and polyunsaturated fatty acid intake in man: a review. Int J Vitam Nutr Res 2000;70:31-42.

16. Calder PC. Dietary modification of inflammation with lipids. Proc Nutr Soc 2002;61:345-58 [review].

17. Praticò D, Dogné JM. Vascular biology of eicosanoids and atherogenesis. Expert Rev Cardiovasc Ther 2009;7:1079-89 [review].

18. Adam O, Beringer C, Kless T, et al. Anti-inflammatory effects of a low arachidonic acid diet and fish oil in patients with rheumatoid arthritis. Rheumatol Int 2003;23:27-36.

19. Harris WS, Mozaffarian D, Rimm E, et al. Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation 2009;119:902-7 [review].

20. Simopoulos AP. The importance of the omega-6/omega-3 fatty acid ratio in cardiovascular disease and other chronic diseases. Exp Biol Med (Maywood) 2008;233:674-88 [review].

21. Hamazaki T, Okuyama H. The Japan Society for Lipid Nutrition recommends to reduce the intake of linoleic acid: a review and critique of the scientific evidence. World Rev Nutr Diet 2003;92:109-32 [review].

22. Plourde M, Cunnane SC. Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements. Appl Physiol Nutr Metab 2007;32:619-34 [review].

23. Kapoor R, Huang YS. Gamma linolenic acid: an antiinflammatory omega-6 fatty acid. Curr Pharm Biotechnol 2006;7:531-4 [review].

24. Harbige LS. Fatty acids, the immune response, and autoimmunity: a question of n-6 essentiality and the balance between n-6 and n-3. Lipids 2003;38:323-41 [review].

25. Pischon T, Hankinson SE, Hotamisligil GS, et al. Habitual dietary intake of n-3 and n-6 fatty acids in relation to inflammatory markers among US men and women. Circulation 2003;108:155-60.

26. Ferrucci L, Cherubini A, Bandinelli S, et al. Relationship of plasma polyunsaturated fatty acids to circulating inflammatory markers. J Clin Endocrinol Metab 2006;91:439-46.

27. Harris WS, Mozaffarian D, Rimm E, et al. Omega-6 fatty acids and risk for cardiovascular disease: a science advisory from the American Heart Association Nutrition Subcommittee of the Council on Nutrition, Physical Activity, and Metabolism; Council on Cardiovascular Nursing; and Council on Epidemiology and Prevention. Circulation 2009;119:902-7 [review].

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