Omega-6 Fatty Acids

Omega-6 essential fatty acids, found in polyunsaturated vegetable oils, are generally necessary for stimulating skin and hair growth, regulating metabolism, promoting the transport of fatty acids from the liver to the tissues, and maintaining reproductive performance. Researchers believe they play an important role in reducing the risk of heart disease, cancer, and stroke. Yet experts estimate that up to 80 percent of Americans consume an insufficient quantity of omega-6 fatty acids.

Uses

The omega-6 fatty acids offer a variety of potential therapeutic uses, particularly for patients with the following conditions.

• Rheumatoid arthritis: Omega-6 acids may reduce inflammation.
• Diabetes: Omega-6 fatty acid supplementation may assist nerve function and help prevent nerve disease in diabetics.
• Cancer: Gamma-linolenic acid (GLA) of the omega-6 series may suppress tumor growth and metastasis (spread), particularly in colon cancer, breast cancer, and melanoma.
• Heart disease: GLA may prevent heart disease by reducing atherosclerosis ("hardening of the arteries") and lowering blood pressure.
• Eye disease: GLA may be beneficial in dry-eye conditions.

Dietary Sources

The American diet provides more than 10 times the needed amount of omega-6 oils in the form of linoleic acid. This is because it comprises the primary oil ingredient added to most processed foods and are found in commonly used cooking oils, such as sunflower oil, safflower oil, corn oil, and soybean oil. However, our consumption of refined fats and oils actually inhibits our body's ability to use the essential fatty acids we consume.

Omega-6 fatty acids are found in the plant seed oils of evening primrose, black currant, borage, and fungal oils.

Arachidonic acid of the omega-6 series is found in egg yolk, organ meats, and other animal-based foods.

Other Forms

Omega-6 fatty acids are commercially available in oils that contain linoleic acid and gamma-linolenic acid.

How to Take It

Recommended doses of omega-6 fatty acids vary depending on the health condition being treated. The following are general guidelines.

• There is no Recommended Dietary Allowance (RDA).
• The recommended dosage for rheumatoid arthritis is 1.4 g per day of GLA.
• Supplementation with 480 mg of GLA per day for diabetes is recommended.
• Studies have shown that up to 2.8 g of GLA per day is well tolerated.
• A healthy person eating a normal diet should reduce consumption of saturated fats and increase consumption of the polyunsaturated essential fatty acids.
• Your health care provider can guide you on the proper ratio in your diet of omega-6 oils to omega-3 oils (should be a 4:1 ratio).

Precautions

Dietary sources of omega-6 acids appear to be completely nontoxic.

Possible Interactions

No harmful drug interactions have been reported.

Supporting Research

Bolton-Smith C, Woodward M, Tavendale R. Evidence for age-related differences in the fatty acid composition of human adipose tissue, independent of diet. Eur J Clin Nutr. 1997;51(9):619-624.

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Ensminger AH, Ensminger ME, Konlande JE, Robson JRK. Foods & Nutrition Encyclopedia. 2nd ed. Boca Raton, Fla: CRC Press, Inc.; 1994:684-708.

Fan YY, Chapkin RS. Importance of dietary gamma-linolenic acid in human health and nutrition. J Nutr. 1998; 128(9): 1411-1414.

Garrison RH Jr, Somer E. The Nutrition Desk Reference. 3rd ed. New Canaan, Conn: Keats Publishing, Inc.; 1995:23-64.

Haas EM. Staying Healthy with Nutrition. Berkley, Calif: Celestial Arts Publishing; 1992:65-79.

Jiang WG, Hiscox S, Bryce RP, Horrobin DF, Mansel RE. The effects of n-6 polyunsaturated fatty acids on the expression of nm-23 in human cancer cells. Br J Cancer. 1998;77(5):731-738.

Jiang WG, Hiscox S, Horrobin DF, Bryce RP, Mansel RE. Gamma linolenic acid regulates expression of maspin and the motility of cancer cells. Biochem Biophys Res Commun. 1997;237(3): 639-644.

Kruger MC, Coetzer H, DeWinter R, Gericke G, Papendorp DH. Calcium, gamma-linolenic acid and eicosapentaenoic acid supplementation in senile osteoporosis. Aging(Milano). 1998;10(5):385-394.

Murray MT. Encyclopedia of Nutritional Supplements. Rocklin, Calif: Prima Publishing; 1996:239-278.

Newstrom H. Nutrients Catalog. Jefferson, NC: McFarland & Co. Inc; 1993:103-105.

Shils ME, Olson JA, Shike M, Ross AC. Modern Nutrition in Health and Disease. 9th ed. Baltimore, Md: Williams & Wilkins; 1999:90-92, 1377-1378.

Wagner W, Nootbaar-Wagner U. Prophylactic treatment of migraine with gamma-linolenic and alpha-linolenic acids. Cephalalgia. 1997;17(2):127-130.

Werbach MR. Nutritional Influences on Illness. 2nd ed. Tarzana, Calif: Third Line Press; 1993:13-22, 655-671.

Ziegler EE, Filer LJ, eds. Present Knowledge in Nutrition. 7th ed. Washington, DC: ILSI Press; 1996:58-64.

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