Journal of Renal Nutrition
Volume 16, Issue 3 , Pages e7-e10, July 2006

Omega 3 Fatty Acids

  • Joan Brookhyser, RD, CSR, CD

      Affiliations

    • Corresponding Author InformationAddress reprint requests to Joan Brookhyser, RD, CSR, CD, 4700 Pointe Fosdick Drive Northwest, Suite 101, Gig Harbor, WA 98335.

St. Joseph Dialysis Center, Gig Harbor, Washington.

Article Outline

 

THE USE OF omega 3 fatty acids in chronic kidney disease (CKD) patients has received a great deal of attention. Possible therapeutic applications include cardiovascular disease, uremia pruritus, erythropoietin resistance, hypertriglyceridemia, vascular access graft thrombosis, depressed albumin levels, and delaying the progression of CKD in certain diseases such as immunoglobulin A (IgA) nephropathy and lupus nephritis.1, 2, 3, 4, 5, 6, 7

The best source of omega 3 fatty acids remains debatable, but most literature supports the use of omega 3 fatty acids that have been metabolized to their final end product: docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).3, 8 EPA and DHA seem to reduce inflammatory activity by displacing arachidonic acid, which is the major precursor for proinflammatory processes. These inflammatory processes are thought to contribute to such conditions as hypoalbuminuria, pruritus, erythropoietin resistance, IgA nephropathy, and lupus nephritis.6

Other mechanisms of action include that omega 3 fatty acids are incorporated into the bilayer of cells, resulting in different membrane characteristics. These alterations may result in altered cell signaling, such as decreased platelet aggregation. This could explain the reason for improved graft patency and decreased cardiac events seen in studies using omega 3 fatty acids.3

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Sources of Omega 3 Fatty Acids 

Food preferences and product tolerances will determine what sources are best for your CKD patient. There are two different ways to obtain omega 3 fatty acids from food. One can consume foods high in EPA and DHA, or consume foods high in alpha linolenic acid (ALA), which then needs to be converted to EPA and DHA (done through an elongation process). One can also use omega 3 fatty acids supplements in their final elongated form of EPA and DHA. Other literature suggests that a combination of sources may be the most effective for the overall health benefits of omega 3 fatty acids in CKD.9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19

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Food Sources of Omega 3 Fatty Acids 

Foods sources of omega 3 fatty acids can achieve some or all of patient needs for these fatty acids (Table 1). However, it may be difficult to meet this requirement to achieve some of the therapeutic benefits as shown below. ALA is the major omega 3 fatty acid in the human diet. However, the desaturation and elongation enzymes that convert ALA to EPA and DHA can vary from less than 0.1% into DHA and 15% into EPA.4, 9, 10, 11 DHA seems to be the most limiting in this conversion and may be one reason more preformed DHA will be important in therapeutic treatment.9, 10, 11 The desaturation and elongation enzymes that convert ALA acid to EPA also convert linoleic acid (LA) to arachidonic acid. Although ALA is the preferred substrate for this pathway, only small amounts of ALA are converted to EPA, probably because of the high ratio of LA:ALA present in cells. This is suggested as a reflection of the high ratio of LA:ALA observed in our Western diets. The ideal ratio of ALA to LA is 4:1; the typical American diet is estimated at 20:1.15, 17

Table 1. Plant and Animal Sources
PortionOmega 3 gCaloriesProtein (g)NA (mg)K+ (mg)P04 (mg)
Plant sources
Flaxseed oil (linseed oil)1tablespoon7.11200000
Canola oil (rapeseed oil)1tablespoon1.61240000
Sunflower or safflower oil1tablespoon0.21200000
Coconut oil1tablespoon0.81170000
Wheat germ oil1tablespoon1.01200000
Egg with enhanced omega 3 fatty acids⁎50 g0.5660–75660–6560–16560–80
Soybeans, roasted⁎3 oz1.5387–49930–342–1401,264–1,173312–558
Walnuts, english3 oz6.8555133375–580194
Walnuts, black3 oz3.3525203444435
Spinach-raw chopped1 cup.397<12416715
Broccoli-raw1 cup.0972532528758
Animal sources
Tuna, raw⁎3 oz0.24–1.28118–12020–2533–40214–484208–216
Tuna, light canned, drained, in oil3 oz0.2616825301176264
Tuna, white, canned in water, drained3 oz0.7310920320201184
Salmon, pink, canned3 oz1.489015420173141
Salmon, chinook, raw3 oz1.481531640335246
Salmon, Atlantic wild, raw3 oz0.9–1.561211737417170
Salmon, Atlantic farmed, raw3 oz1.09–1.831561650308198
Halibut, raw⁎3 oz0.4–1.075–12018–2148–58353–383189–242

Note. Data from USDA Nutrient Database for Standard Reference, National Sunflower Association, Flax Council of Canada; Mahan L and Escott-Stump S: Krause’s Food, Nutrition and Diet Therapy, 11th ed. New York, Elsevier, 2004, pp. 1244-1245; Pennington J, Douglas J: Bowes and Church’s Food Values of Portions Commonly Used, 18th Ed. Baltimore, MD, Lippincott, Williams, and Wilkins, 2005; Patel G. Essential fats in walnuts are good for the heart and diabetes. J Am Diet Assoc 105:1096-1097, 2005; and Raper N, Cronin F, Exler J: Omega-3 fatty acid content of the US food supply. J Am Coll Nutr 11:304-308, 1992

⁎ More than one product was evaluated to determine this range of values.

Patients should be counseled on avoiding over consumption of LA to optimize elongation from food high in ALA. The LA will compete for the same elongase and desaturase enzymes, interfering with omega 3 fatty acids metabolism to DHA and EPA from ALA.4

The literature is unclear regarding whether this elongation process is as efficient in diabetes mellitus and certain dermatological conditions, potentially because of a lack of the necessary enzyme (catalyst) for making this conversion. Other variables possibly impacting this conversation are trans fats, age, and gender. For people choosing to take ALA versus preformed EPA and DHA, consuming oils high in gamma linolenic acid (GLA) may help in this rate-limiting step delta 6-desaturase (D6D), such as black current oil, evening primrose oil, or borage oil. Vitamin B6 may also help in this conversion process.14, 19, 20, 21

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Dosing Recommendations 

The recommended oral dose of omega 3 fatty acids depends on the indication. The following doses are recommended1, 3:

•1 to 2 g/day to lower triglycerides

•4 g/day to lower blood pressure

•4 to 6 g/day to prevent thrombosis after placement of a hemodialysis graft

•6 g/day for treatment of uremic pruritus

•1 to 8 g EPA and 1.2 g DHA for IgA nephropathy

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Supplements of Omega 3 

For many patients, taking a supplement of omega 3 will be easier given the higher dose they may require. Table 2 is a list of recommended products based on current literature and resources available. These products were based on contents that seem acceptable to CKD patients and are more concentrated in content (to avoid the necessity of excess pill volume).

Table 2. A Sampling of Omega 3 Supplements
ProductManufacturer City and State Contact NumberContents
Advocare Omegaplex Advocare International www.advocare.comCarrollton, TX 972-478-4500Per soft gel: 300 mg EPA and 200 mg DHA
Coromega Erbl, Inc. www.coromega.comVista, CA 877-275-3725Per packet: 20 calories, 350 mg EPA, 230 mg DHA, 70 mg other omega 3s, 25 mg vitamin C, 3 IU vitamin E, 50 μg folic acid.
Other ingredients: egg yolk, 5 mg stevia leaf extract (sweetener), natural orange flavor, and vanillin
Kirkland Signature Natural Fish Oil Concentrate Costco Wholesale Corporation www.costco.comIssaquah, WA 800-774-2678Per soft gel: 150 mg EPA, 100 mg DHA
Vitamin World Naturally Inspired Super DHA Natural Fish Oil Vitamin World www.vitaminworld.comBohemia, NY 888-645-7135Per soft gel: 10 calories, 300 mg EPA, 200 mg DHA.
Other ingredients: gelatin and glycerin
Carlson Super Omega 3 Fish Oils www.carlsonlab.comArlington Heights, IL 847-255-1600Per soft gel: 10 calories, 300 mg EPA, 200 mg DHA, 10 IU vitamin E (d-alpha).
Other ingredients: beef gelatin, glycerin, water
Omega-3 700 Solgar Vitamin and Herb www.Solgar.comLeonia, NJ 877-SOLGAR-4Per soft gel: 15 calories. 360 mg EPA, 240 mg DHA, 100 mg other omega-3s, 4 IU vitamin E.
Other ingredients: caramel
Omacor www.omacorrx.comReliant Pharmaceuticals 877-311-7515Per capsule: 465 mg EPA, 375 mg DHA, 60 mg DPA (docosapentaenoic acid)

Note. Data from www.consumerlab.com and www.supplementinfo.org.

Abbreviations: DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid.

For CKD patients, it is best to avoid products with added vitamin A and D, most likely derived from halibut or shark oils. Fish oil supplements that contain some vitamin E have been recommended to prevent rancidity.1, 4 In addition to EPA and DHA, some products contain mixed oil supplements. These additions are often expensive and unnecessary. Products that contain mainly EPA and DHA should be recommended.

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Risks 

Until recently, risks associated with omega 3 fatty acid supplements seemed minimal. Some concerns pertain to excessive intake on immune function and potentially increased risk of excessive bleeding and hemorrhagic stroke. An intake of <2 g/day is unlikely to cause this bleeding.4 A recent study suggested that patients with pacemakers might be at a slightly higher risk for arrhythmias with omega 3 supplements.18

If one is taking anticoagulation agents, in addition to omega 3 supplements, it has been suggested to routinely check prothrombin times (PT), in addition to careful monitoring of unusual bruising.1

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References 

  1. Burrowes J , VanHouten G . Use of alternative medicine by patients with stage 5 chronic kidney disease . Adv Chronic Kidney Dis . 2005;12:312–325
  2. Fiedler R , Mall M , Mall C , et al.   Short-term administration of omega-3 fatty acid in hemodialysis patients with balanced lipid metabolism . J Ren Nutr . 2005;15:253–256
  3. Donadio J . Briefing Document on the Potential Benefits of Omega 3 Fatty Acids . Rochester, MN: Mayo Nephrology Collaborative Group; 2003;
  4. Omega 3 fatty acids. Dietary Supplement Issue No. 15, Vol. 4, Number 2, March-April 2003
  5. Clark WF , Parbtani A . Symposium on essential fatty acid deficiency and omega 3 unsaturated fat in glomerulonephritis (basis and practice) . Am J Kidney Dis . 1994;23:644–647
  6. Nephrology Pharmacy Association . Role of fish oil in dialysis . Med Facts . 2002;4:2
  7. Vergili-Nelson J . Benefits of fish oil supplementation for hemodialysis patients . J Am Diet Assoc . 2003;103:1174–1177
  8. www.naturaldatabase.com. Accessed September 2005.
  9. Gerster H . Can adults adequately convert alpha linolenic acid to eicosapentaenoic acid and docosahexaenoic acid . Int J Vitamin Nutr Res . 1998;68:159–173
  10. Mantzioaris E , James M , Gibson R , Clelland L . Dietary substitution with an alpha-lipoic acid rich vegetable oil increases eicosapentaneoic acid concentration in the tissues . Am J Clin Nutr . 1997;65(Suppl 5):1304–1309
  11. Brenna JT . Efficiency of conversion of alpha linolenic acid to long chain n-3 fatty acids in man . Curr Opin Nutr Metab Care . 2002;5:127–132
  12. Burdge GC , Calder PC . Conversion of alpha-linolenic acid to longer-chain polyunsaturated fatty acids in human adults . Reprod Nutr Dev . 2005;45:587–597
  13. Williams CM , Burdge G . Long-chain n-3 PUFA (plant v. marine sources) . Proc Nutr Soc . 2006;65:42–50
  14. Messina V , Mangels R , Messina M . In: The Dietitian’s Guide to Vegetarian Diets . (ed 2). 2005;p. 85–98 Sandbury, Massachusetts
  15. Patel G . Essential fats in walnuts are good for the heart and diabetes . J Am Diet Assoc . 2005;105:1096–1097
  16. DeLorgeril M , Salen P . Use and misuse of dietary fatty acids for the prevention and treatment of coronary heart disease . Reprod Nutr Dev . 2004;44:283–288
  17. deLorgeril M , Salen P . Alpha-linolenic acid and coronary heart disease . Nutr Metab Cardiovasc Dis . 2004;14:162–169
  18. Sinclar AJ , Attar-Bashi NM . What is the role of alpha-linolenic acid for mammals? . Lipids . 2002;37:1113–1123
  19. Bordoni A , Hrelia S , Lorenzini A , et al.   Dual influence of aging and vitamin B-6 deficiency on delta-67-desaturation of essential fatty acids in rat liver microsome . Prostaglandins Leukot Essent Fatty Acids . 1998;58:417–420
  20. Oxholm A , Oxholm P , daCunhaBang F , Horrobin DF . Abnormal essential fatty acid metabolism in Darier’s disease . Arch Dermatol . 1990;126:1308–1311
  21. Raitt M , Conneor W , Morris C , et al.   Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patient with implantable defibrillators . JAMA . 2005;293:1308–1311

PII: S1051-2276(06)00083-5

doi:10.1053/j.jrn.2006.04.003

Journal of Renal Nutrition
Volume 16, Issue 3 , Pages e7-e10, July 2006

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