Home Articles Fishy Advice: Part I

Fishy Advice: Part I

Written on January 31, 2008 at 8:54 am, by Eric Cressey

By Eric Cressey

If you’re even remotely up-to-date on your nutrition-for-health reading, you’re well aware of the benefits of fish oil. Moreover, if you’re anything like me, you’ve also gone to great lengths–often to no avail–to convince people that they should be taking it even if it does sound “icky.” In an effort to save you and I a lot of future time and energy, I’ve compiled the following for you to share with your relatives, mailman, proctologist, lunchlady, and anyone else with whom you associate that isn’t currently “on da fish.”

Based on undeniable scientific evidence and anecdotal evidence, I strongly encourage you to incorporate into your diet two specific omega-3 fatty acids: eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA), commonly referred to as fish oils. EPA and DHA deficiencies have been linked to problems that include, but are certainly not limited to heart disease, hypertension, arthritis, cancer, immune disorders, chronic intestinal disorders, growth retardation, liver disorders, skin lesions, reproductive failure, visual problems, kidney disorders, and neurological disorders (1).

Dietary alpha-linolenic acid can be converted to EPA and DHA in the body for utilization as important raw materials in healthy cell membranes. Significant amounts of alpha-linolenic acid can be found in the following oils: flaxseed, soybean, hempseed, pumpkinseed, canola, wheat germ and walnut. Products such as margarine and shortening that are derived from these oils also contain modest amounts of alpha-linolenic acid. Some nuts and seeds– butternuts, walnuts, pumpkinseeds, and flaxseeds– and vegetables (soybeans) are good sources as well (1). However, the conversion of alpha-linolenic acid to EPA and DHA is quite inefficient; estimates place the conversion rates at less than 5-10% for EPA and 2-5% for DHA (2). Lifestyle factors can also negatively influence these conversions. There is also evidence to suggest that females are more efficient at converting linolenic acid than men; this is likely due to increased demands for EPA and DHA during pregnancy and lactation (3). Even if you eat plenty of the aforementioned foods regularly, you still might come up short on EPA and DHA because the fatty acid quality is often degraded due to the typical overprocessing that occurs in commercial production (4). As such, it is best to get your EPA and DHA directly whenever possible.

EPA and DHA are commonly referred to as fish oils because coldwater fish are by far the best sources. Although the terms EPA/DHA and fish oils are substituted for one another in writing and conversation, EPA and DHA are actually just two kinds of fatty acids contained in fish oils (5). These fish include, but are not limited to: salmon, mackerel, bluefish, tuna, mullet, herring, anchovy, and sardines. Infants receive plenty of EPA and DHA from their mothers’ milk (1). Certainly, eating fish every day isn’t appetizing for most people, and drinking human milk after the age of one is neither feasible nor socially acceptable! Plus, the typical vegetarian diet is extremely low in alpha-linolenic acid, so even if conversion was efficient, these individuals would still be coming up short (clinical studies have proven that vegetarians have insufficient levels of EPA and DHA) (2). Luckily, fish oil supplements in both liquid and softgel form are widely available to ensure that EPA and DHA requirements can be met easily.

EPA and DHA exert their most powerful effects in an anti-inflammatory role. Arachidonic acid, which is created out of the omega-6 fatty acids in our diets, serves as the building block for certain eicosanoids that control the synthesis of cytokines that are pro-inflammatory and immunoregulatory; when these cytokines are overproduced, chronic inflammatory diseases (and even septic shock) can result. Omega-3 fatty acids, on the other hand, inhibit the production of arachidonic acid–thus preventing the production of certain mediators of inflammation–and serve as the raw materials for a healthier class of eicosanoids with anti-inflammatory properties (6). Given how out-of-whack the typical diet is in terms of the omega-6: omega-3 ratio, it should come as no surprise that the world is as unhealthy as it is!

Here is some pretty impressive data on a variety of fronts:

Cardiovascular Health/Atherosclerosis/Hyperlipidemia/Hypertension:

  • An eleven year study of 20,557 male U.S. physicians showed that those who consumed fatty fish at least once per week were 52% less likely to suffer a sudden cardiac death than those who only ate it once per month or less (5).
  • The typical Greenland Eskimo diet is devoid of fruits and vegetables and very high in fats from animal sources: not your traditional “heart healthy diet.” However, the Eskimos had far lower instances of coronary heart disease (CHD) than a Denmark population of nearly identical ethnical composition (same ancestors). The Eskimo and Danish diets both consisted of a high percentage of calories from fat (39% and 42%, respectively), so why didn’t the Eskimos suffer from such CHD like the Danes and everyone else? The secret lay with the types of fat that the Eskimos were eating. The typical Danish diet consisted of 22% of total calories from saturated fat and less than 1% from omega-3 polyunsaturated fatty acids (PUFAs). Meanwhile, only 9% of total calories in the Eskimo diet came from saturated fat. Perhaps more importantly, 4.2% of the Eskimos’ total calories came from omega-3 PUFAs (5). Similar trends are readily apparent in coastal villages of Korea and Japan and throughout Scandinavian countries. Not surprisingly, they all rely extensively on coldwater fish in their everyday lives. Need further proof? A recent comparison of two Japanese villages: one fishing, one farming, found that the farming village had eight times more atherosclerotic plaques than their fishing counterparts (7).
  • In a study of 59 patients with diagnosed heart disease, Durrington et al (2001) monitored the effects of 2 g daily of Omacor, a pharmaceutical grade fish oil concentrate. The researchers found that “there was a sustained significant decrease in serum triglycerides by 20-30% and in very low density lipoprotein (VLDL) cholesterol by 30-40% in patients receiving active Omacor at three, six, and 12 months compared either to baseline or placebo (8).”
  • Not only do fish oils lower serum triglycerides and, in high dosages and combination with dietary modifications, low density lipoprotein (LDL) cholesterol, but they also decrease arterial platelet collection, which can lead to dangerous clots (5).
  • Harper and Jacobsen (2001) reported that randomized clinical trials with fish oils “have demonstrated reductions in risk that compare favorably with those seen in landmark secondary prevention trials with lipid-lowering drugs (5).”
  • Following coronary artery bypass surgery with venous grafts, patients that receive 4 g per day of omega-3 fatty acids have a significantly lower risk of graft occlusion (obstruction/closure) (9).


  • There are like 80 bizillion studies out there proving that fish oil reduces blood pressure (although you’ll obviously derive greater benefits if you eat right and exercise, too). That said, 4 g omega-3 fatty acids per day is the minimum you’ll need to see an improvement (9). You can expect not only reduced blood pressure, but also decreased vascular wall thickness (10). I’ve included a few more references (11-13) for those of you that either don’t believe me or have a lot of time on your hands for extra reading.

Cardiac Arrhythmias:

  • There is significant backing for the assertion that fish oils’ antiarrhymthic capacity is the most important. Without sufficient EFAs, the body is forced to make cell membranes out of saturated fatty acids, which yield membranes that are far less elastic. When cardiac cells are made from EFAs (and are thus appropriately elastic), the heart has an easier time returning to a resting state. However, the rigid cell membranes made from saturated fatty acids can cause arrhythmias and alter the cardiac muscle cell contraction (5).

Inflammatory Diseases of Joints and Connective Tissues:

  • In patients with degenerative and inflammatory joint diseases, supplementation with omega-3 fatty acids decreases both the “degradative and inflammatory aspects of chondrocyte metabolism, whilst having no effect on the normal tissue homeostasis (14).”
  • Chondrocytes are the building blocks of articular cartilage and work with the extracellular matrix of collagen and proteoglycans to dissipate forces. If the cartilage is constantly eroding due to chondrocyte degradation, the structure tends to soften as its water content increases. Interventions with omega-3 fatty acids are effective in reducing these negative trends and their related symptoms in most patients with osteoarthritis (15,16).
  • In more than two dozen studies, researchers have found that fish oil supplementation reduces fatigue and stiffness in rheumatoid arthritis (RA) afflicted individuals. In fact, some studies found the effects to be dramatic enough to allow for substantial decreases in nonsteroidal anti-inflammatory drug (NSAID) dosages (16-18). Generally speaking, in trials of 3 g combined EPA and DHA (the minimum recommended dose for RA patients), the benefits of fish oil supplementation were not noticeable until the 12-week mark, so be patient! On a microscopic level, the omega-3 supplementation tended to limit the release of leukotrien B(4) and interleukin 1 from neutrophils and monocytes. In plain English, this means that two inflammation-causing factors were present in lesser quantities (17).
  • RA patients that supplemented with Vitamin E and fish oil showed an even greater decrease in NSAID requirements, indicating a synergistic effect between the two (18).
  • Raynaud’s Phenomenon is a vascular disorder that falls under the inflammatory diseases of joints and connective tissues. In this condition, tiny blood vessels that feed the skin periodically contract (called a “vasospasm”), limiting blood flow to the skin. As oxygen deprivation sets in, the skin–especially in the hands and feet–turns white and eventually blue. There is speculation that this phenomenon is due to the body’s overreaction to cold, as the body excessively vasoconstricts these arteries to conserve heat. However, while cold atmospheres are most likely to cause a vasospasm, emotional stress can be a causative factor as well. Because omega-3 fatty acids “induce a favorable response to vascular ischemia,” they have been investigated as a potential treatment for Raynaud’s. DiGiacomo et al (1989) found that fish oil supplementation improved cold exposure tolerance and significantly delayed the onset of vasospasm in Raynaud’s patients. Furthermore, this cold tolerance improvement was associated with a significantly increased digital systolic blood pressure in a cold atmosphere (20).
  • Systemic lupus erythematosus (SLE) — better known simply as lupus – is a chronic, autoimmune rheumatic disease with a wide variety of symptoms. Typically, this disease affects women of childbearing age (21). Symptoms include arthritis, skin rash, vascular inflammation, and profound effects on the central nervous, renal and cardiopulmonary systems (22). Mohan and Das (1997) found that concentrations of EPA and DHA were low in the plasma phospholipids of SLE patients; this supported pre-existing data that EPA and DHA supplementation could lead to clinical remission without side effects (22).
  • In cases of pediatric SLE, dyslipoproteinemia — essentially high triglycerides, low HDL, and high LDL – is often present. Provision of fish oil supplements has proven effective in significantly improving blood lipid profiles (decreased serum triglycerides concentrations) in these patients beyond dietary intervention alone (24).


  • Two short-term studies have found that a lower omega-6 to omega-3 fatty acid ratio (achieved via omega-3 supplementation) attenuates bone loss in patients with osteoporosis. These effects are likely due to decreases in the production of Prostaglandin E2 (PGE2), an eicosanoid widely implicated in bone resorption (25). Overall eicosanoid balance is largely dependent on fatty acid intake; so it’s important to consider both the quantity of omega-3s and omega-6s present.

Kidney Disease/Renal Failure:

  • Researchers at the Mayo Nephrology Collaborative Clinic found that fish oils slowed the progression of immunoglobin A nephropathy in patients at a high risk for kidney disease (26).
  • Omega-3s have shown promise in reducing urinary calcium levels in kidney stone patients and preventing blood clots in hemodialysis patients (26).
  • Hemodialysis patients given fish oil required 16% less erythropoietin while experiencing a 3.6% increase in serum albumin levels in comparison to a placebo group (27).
  • The side effects (such as skin lesions and hyperlipidemia) of cyclosporine, a medication often prescribed for kidney transplant patients, are noticeably less significant when patients supplement with fish oil (28)

Prostate Cancer:

  • A longitudinal study of 6,272 Swedish men showed that those who regularly consumed fish were approximately 50% less likely to be diagnosed with prostate cancer and roughly 70% less likely to die from it than those who avoided fish. Three servings per week appeared to be the minimum amount needed to attain such benefits (29).
  • Augustsson et al (2003) validated the Swedish study with a larger sample size of 47,882, and noted that the strongest association also existed between fish consumption and metastatic cancer (meaning that it’s extensive and spreads to other parts of the body via the blood vessels or lymphatic system). Those men that ate fish more than three times per week were 24% less likely to be diagnosed with metastatic cancer (30).

Colon Cancer:

  • Collett et al noted that incidences of colon cancer in rats were reduced significantly with DHA supplementation in the form of fish oil (31).

Breast Cancer:

  • In a five-year prospective study of 35,298 Singapore Chinese women ages 45-74, high levels of dietary omega-3 fatty acids (mostly from shellfish) were associated with a significantly reduced (26% lower) risk of breast cancer (32).

Skin Cancer:

  • In animals, omega-3 fatty acids have been proven effective as protection against photocarcinogenesis, likely due to the fatty acids’ ability to combat oxidative stress. Rhodes et al studied the effect of 4 g/day EPA supplementation “on a range of indicators of ultraviolet radiation (UVR)-induced DNA damage in humans, and assessed effect on basal and post-UVR oxidative status” in 42 healthy subjects. The control group received oleic acid, a monounsaturated fatty acid, for the three-month study. Sunburn sensitivity was reduced in the EPA group only; likewise, other early markers of skin cancer diminished significantly with EPA supplementation. These results imply that there was protection against acute UVR-induced damage by dietary EPA; the researchers hypothesized that “longer-term supplementation might reduce skin cancer in humans (33).”

That concludes part one; hopefully, you’ve picked up some valuable information. Next month, I’ll besiege you with another 8,471 references supporting my argument on a variety of different fronts. Stay tuned!


1. Whitney, E.N. & Rolfes, S.R. Understanding Nutrition: (8th ed.). Belmont, CA: Wadsworth Publishing Company, 1999.

2. Davis BC, Kris-Etherton PM. Achieving optimal essential fatty acid status in vegetarians: current knowledge and practical implications. Am J Clin Nutr. 2003 Sep;78(3 Suppl):640S-646S.

3. Burdge GC, Wootton SA. Conversion of alpha-linolenic acid to eicosapentaenoic, docosapentaenoic and docosahexaenoic acids in young women. Br J Nutr. 2002 Oct;88(4):411-20.

4. Colgan, M. Optimum Sports Nutrition. New York: Advanced Research Press, 1993.

5. Harper CR, Jacobson TA. The fats of life: the role of omega-3 fatty acids in the prevention of coronary heart disease. Arch Intern Med. 2001 Oct 8;161(18):2185-92.

6. Calder PC. n-3 polyunsaturated fatty acids and cytokine production in health and disease. Ann Nutr Metab. 1997;41(4):203-34.

7. Yamada T, Strong JP, Ishii T, Ueno T, Koyama M, Wagayama H, Shimizu A, Sakai T, Malcom GT, Guzman MA. Atherosclerosis and omega-3 fatty acids in the populations of a fishing village and a farming village in Japan. Atherosclerosis. 2000 Dec;153(2):469-81.

8. Durrington PN, Bhatnagar D, Mackness MI, Morgan J, Julier K, Khan MA, France M. An omega-3 polyunsaturated fatty acid concentrate administered for one year decreased triglycerides in simvastatin treated patients with coronary heart disease and persisting hypertriglyceridaemia. Heart. 2001 May;85(5):544-8.

9. Nordoy A, Marchioli R, Arnesen H, Videbaek J. n-3 polyunsaturated fatty acids and cardiovascular diseases. Lipids. 2001;36 Suppl:S127-9.

10. Engler MM, Engler MB, Pierson DM, Molteni LB, Molteni A

Effects of docosahexaenoic acid on vascular pathology and reactivity in hypertension. Exp Biol Med (Maywood). 2003 Mar;228(3):299-307.

11. Passfall J, Philipp T, Woermann F, Quass P, Thiede M, Haller H. Different effects of eicosapentaenoic acid and olive oil on blood pressure, intracellular free platelet calcium, and plasma lipids in patients with essential hypertension. Clin Investig. 1993 Aug;71(8):628-33.

12. Bhatnagar D, Durrington PN.Omega-3 fatty acids: their role in the prevention and treatment of atherosclerosis related risk factors and complications. Int J Clin Pract. 2003 May;57(4):305-14

13. Holm T, Andreassen AK, Aukrust P, Andersen K, Geiran OR, Kjekshus J, Simonsen S, Gullestad L. Omega-3 fatty acids improve blood pressure control and preserve renal function in hypertensive heart transplant recipients. Eur Heart J. 2001 Mar;22(5):428-36.

14. Curtis CL, Rees SG, Cramp J, Flannery CR, Hughes CE, Little CB, Williams R, Wilson C, Dent CM, Harwood JL, Caterson B. Effects of n-3 fatty acids on cartilage metabolism. Proc Nutr Soc. 2002 Aug;61(3):381-9.

15. Curtis CL, Rees SG, Little CB, Flannery CR, Hughes CE, Wilson C, Dent CM, Otterness IG, Harwood JL, Caterson B. Pathologic indicators of degradation and inflammation in human osteoarthritic cartilage are abrogated by exposure to n-3 fatty acids. Arthritis Rheum. 2002 Jun;46(6):1544-53.

16. Cho SH, Jung YB, Seong SC, Park HB, Byun KY, Lee DC, Song EK, Son JH. Clinical efficacy and safety of Lyprinol, a patented extract from New Zealand green-lipped mussel (Perna Canaliculus) in patients with osteoarthritis of the hip and knee: a multicenter 2-month clinical trial. Allerg Immunol (Paris). 2003 Jun;35(6):212-6.

17. Kremer JM. n-3 fatty acid supplements in rheumatoid arthritis. Am J Clin Nutr. 2000 Jan;71(1 Suppl):349S-51S

18. Tidow-Kebritchi S, Mobarhan S. Effects of diets containing fish oil and vitamin E on rheumatoid arthritis. Nutr Rev. 2001 Oct;59(10):335-8.

19. Rennie KL, Hughes J, Lang R, Jebb SA. Nutritional management of rheumatoid arthritis: a review of the evidence. J Hum Nutr Diet. 2003 Apr;16(2):97-109.

20. DiGiacomo RA, Kremer JM, Shah DM. Fish-oil dietary supplementation in patients with Raynaud’s phenomenon: a double-blind, controlled, prospective study. Am J Med. 1989 Feb;86(2):158-64.

21. Ioannou Y, Isenberg DA. Current concepts for the management of systemic lupus erythematosus in adults: a therapeutic challenge. Postgrad Med J. 2002 Oct;78(924):599-606.

22. Das UN. Beneficial effect of eicosapentaenoic and docosahexaenoic acids in the management of systemic lupus erythematosus and its relationship to the cytokine network. Prostaglandins Leukot Essent Fatty Acids. 1994 Sep;51(3):207-13.

23. Mohan IK, Das UN. Oxidant stress, anti-oxidants and essential fatty acids in systemic lupus erythematosus. Prostaglandins Leukot Essent Fatty Acids. 1997 Mar;56(3):193-8.

24. Ilowite NT, Copperman N, Leicht T, Kwong T, Jacobson MS. Effects of dietary modification and fish oil supplementation on dyslipoproteinemia in pediatric systemic lupus erythematosus. J Rheumatol. 1995 Jul;22(7):1347-51.

25. Albertazzi P, Coupland K. Polyunsaturated fatty acids. Is there a role in postmenopausal osteoporosis prevention? Maturitas. 2002 May 20;42(1):13-22.

26. Donadio JV. n-3 Fatty acids and their role in nephrologic practice. Curr Opin Nephrol Hypertens. 2001 Sep;10(5):639-42.

27. Vergili-Nelsen JM. Benefits of fish oil supplementation for hemodialysis patients. J Am Diet Assoc. 2003 Sep;103(9):1174-7.

28. Simopoulos AP. Omega-3 fatty acids in health and disease and in growth and development. Am J Clin Nutr. 1991 Sep;54(3):438-63.

29. Terry P, Lichtenstein P, Feychting M, Ahlbom A, Wolk A. Fatty fish consumption and risk of prostate cancer. Lancet. 2001 Jun 2;357(9270):1764-6.

30. Augustsson K, Michaud DS, Rimm EB, Leitzmann MF, Stampfer MJ, Willett WC, Giovannucci E. A prospective study of intake of fish and marine fatty acids and prostate cancer. Cancer Epidemiol Biomarkers Prev. 2003 Jan;12(1):64-7.

31. Collett ED, Davidson LA, Fan YY, Lupton JR, Chapkin RS. n-6 and n-3 polyunsaturated fatty acids differentially modulate oncogenic Ras activation in colonocytes. Am J Physiol Cell Physiol. 2001 May;280(5):C1066-75.

32. Gago-Dominguez M, Yuan JM, Sun CL, Lee HP, Yu MC. Opposing effects of dietary n-3 and n-6 fatty acids on mammary carcinogenesis: The Singapore Chinese Health Study. Br J Cancer. 2003 Nov 3;89(9):1686-92.

33. Rhodes LE, Shahbakhti H, Azurdia RM, Moison RM, Steenwinkel MJ, Homburg MI, Dean MP, McArdle F, Beijersbergen van Henegouwen GM, Epe B, Vink AA. Effect of eicosapentaenoic acid, an omega-3 polyunsaturated fatty acid, on UVR-related cancer risk in humans. An assessment of early genotoxic markers. Carcinogenesis. 2003 May;24(5):919-25.

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