What you need to know about omega-3 fatty acids before recommending them to your patients

What you need to know about omega-3 fatty acids before recommending them to your patients

Although the putative benefits of omega-3 fatty acids are frequently addressed in the lay press and the medical literature, confusion and misperceptions remain. Before recommending omega-3 fatty acids to patients beyond the dietary sources supported by the Institute of Medicine and Dietary Guidelines for Americans, it may behoove the clinician to familiarize himself with the following points:

  1. Not all omega-3 fatty acids are alike- The omega-3 fatty acids encompass a number of fatty acids that have structural similarities but are functionally quite different. An important distinction should therefore be made between the longer chain omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) that are primarily obtained from dietary sources such as cold-water fish, and the shorter chain omega-3 fatty acid alpha-linoleic acid (ALA), which is derived from abundant vegetable seed oils such as soybean or canola oils (please refer to the Food products). It is the former omega-3 fatty acids (i.e. EPA and DHA) that have been most intensively studied and are believed to possess the majority of the clinical benefits 1.
  2. The optimal amount of omega-3 fatty acid intake is not yet known- Intake recommendations vary widely between countries 2. In the United States, the American Heart Association has advised that healthy persons consume (preferably fatty) fish twice weekly, while individuals with established heart disease consume at least 1 gram of fish oil daily 3. The ideal amount of omega-3 intake will probably vary by sex, age, gestational status, and concurrent illnesses (please see Recommendations for intakes of omega-3 fatty acids).
  3. Diet can be a good source of omega-3 fatty acids- While fish oil supplements are widely sold and may provide supraphysiological doses of omega-3 fatty acids, dietary sources such as cold water fish and other marine sources (as well as other select food products that are fortified, ie certain egg products and DHA-fortified orange juice and yogurt) can significantly boost long-chain omega-3 intakes in the relatively omega-3 depleted Western diet. Certain groups, such as the Japanese, actually have dramatically higher omega-3 fatty acid blood levels compared with Americans simply due to differences in dietary intake 4.

References

  1. Wang C, Harris WS, Chung M, Lichtenstein AH, Balk EM, Kupelnick B, Jordan HS, Lau J. n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review. Am J Clin Nutr 2006;84(1):5-17.
  2. Harris WS, Mozaffarian D, Lefevre M, Toner CD, Colombo J, Cunnane SC, Holden JM, Klurfeld DM, Morris MC, Whelan J. Towards establishing dietary reference intakes for eicosapentaenoic and docosahexaenoic acids. J Nutr 2009;139(4):804S-19S.
  3. Kris-Etherton PM, Harris WS, Appel LJ. American Heart Association. Nutrition Committee.Fish consumption, fish oil, omega-3 fatty acids, and cardiovascular disease. Circulation 2002;106(21):2747-57.
  4. Sekikawa A, Curb JD, Ueshima H, El-Saed A, Kadowaki T, Abbott RD, Evans RW, Rodriguez BL, Okamura T, Sutton-Tyrrell K, Nakamura Y, Masaki K, Edmundowicz D, Kashiwagi A, Willcox BJ, Takamiya T, Mitsunami K, Seto TB, Murata K, White RL, Kuller LH. ERA JUMP (Electron-Beam Tomography, Risk Factor Assessment Among Japanese and U.S. Men in the Post-World War II Birth Cohort) Study Group. Marine-derived n-3 fatty acids and atherosclerosis in Japanese, Japanese-American, and white men: a cross-sectional study. J Am Coll Cardiol 2008;52(6):417-24.

Key Points

  • Omega-3 fatty acids, EPA and DHA, are believed to possess the majority of the clinical benefits for this family of fatty acids.
  • The optimal amount of omega-3 fatty acid intakes has not yet been identified.
  • Diet is a good source of omega-3 fatty acids but the amounts and types vary in the diet.