Some seemingly conflicting research results can leave people confused about whether or not fish is a healthy option. A major reason for this confusion is we’re told fish oils contain omega-3 fatty acids which our bodies need to function properly. So if fish oils contain this vital ingredient, what’s the problem with tucking into a nice piece of salmon?
The issue is not whether the omega-3 in fish is of itself healthy or not, but whether we need to eat fish in order to get the omega-3 our bodies need.
Omega-3 (alpha-linolenic acid or ALA and also written as n-3) are long-chain essential polyunsaturated fatty acids. They are called “essential” because our bodies can’t make them. Therefore, it’s essential that we get them from food.[su_box title=”There are three main omega-3 polyunsaturated fatty acids (PUFA’s)” style=”soft” box_color=”#f8f1e8″ title_color=”#07114e”]Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA), and Alpha-linolenic acid (ALA).[/su_box]
ALA is a precursor for the production of EPA and DHA.
EPA and DHA are predominantly found in fish and that’s why they are often referred to as marine omega-3’s.
Those who don’t eat fish can find ALA in whole grains, leafy green vegetables, soy, seeds and nuts (particularly walnuts, flaxseeds, and chia seeds). But the body then has to get on with the job of converting it into EPA ad DHA – some ALA is used for energy production, so only a limited amount is converted into EPA and DHA.
Much debate goes on, therefore, about whether those people who don’t eat “ready-made” EPA and DHA from fish are able to get sufficient ALA in their diets to produce the EPA and DHA that the body requires.
At this stage, discussions about which source is best usually ends up with a reductionist downward spiral, normally focusing solely on an isolated process or nutrient – in this case omega-3. The forest disappears behind the tree.
The more specific issues of plant-based omega-3 quality and quantity will be covered in depth in further articles.
For the time being, I just want to suggest that we would do better by viewing this whole subject from a broader perspective so that we can see the bigger picture.
Over 100 years worth of peer-reviewed published studies have demonstrated links between eating animal products and a range of diseases, including diabetes, obesity, heart disease and cancer. At the same time, whole plant foods have been shown to have quite the opposite effect – acting as natural protection against such diseases.
Added to this are the not-inconsiderable concerns about pollutants in fish and the dangers associated with fish oil supplements. So, why bother killing our fishy friends for something we can get from plants?
The amount of phytonutrients in fish oils is minimal when compared to those found in whole plants. And when you eat whole plants, rather than the oils that can be fragmented from them – almond oil from almonds, olive oil from olives – there are none of the negative side-effects associated with consuming oils – whether derived from animals or plants.
This is why we benefit from looking at the common denominator within nutritional research – namely, that what comes out on top every time is the consumption of more whole plants.
As Professor T Colin Campbell points out repeatedly, single mechanisms can give us clues about the inexpressible complexity of the biochemical systems and interrelations within the human body, but these single elements can never provide an overview of the ‘big picture’ of human health. This is something that can only be appreciated by drawing in data from a wide-range of sources. Amongst these are:
- Large-scale observational studies over time on whole populations – such as the 800 million Chinese forming the basis of The China Study, and the half million Europeans forming the basis of the EPIC study.
- Smaller-scale, controlled, interventional studies – such as Dr Dean Ornish’s work on prostate cancer, Dr Caldwell B Esselstyn’s work on heart disease, and Dr N Barnard’s work on diabetes.
- Highly specific and detailed research to find and explain the mechanisms that might produce the results seen in the above studies – such as Professor T Colin Campbell’s work on the role of animal protein in cancer initiation, promotion & progression, and Dr David Jenkins’ work on glycaemic load.
If any one of these three approaches were producing contrary findings to the other two, then there would be room for serious doubt; but all three point in exactly the same direction – that a WFPBD with no added salt, oil or sugar is consistently shown to be the healthiest diet for the human body, both in terms of morbidity and mortality.
So where does this leave the omega-3 in fish?
Well, let’s just leave it in the fish…
Dr John McDougall – Confessions of a Fish Killer. https://www.drmcdougall.com/misc/2007nl/jun/confessions.htm
Worm B, Barbier EB, Beaumont N, Duffy JE, Folke C, Halpern BS, Jackson JB, Lotze HK, Micheli F, Palumbi SR, Sala E, Selkoe KA, Stachowicz JJ, Watson R. Impacts of biodiversity loss on ocean ecosystem services. Science. 2006 Nov 3;314(5800):787-90.
Hibbeln JR, Davis JM, Steer C, Emmett P, Rogers I, Williams C, Golding J. Maternal seafood consumption in pregnancy and neurodevelopmental outcomes in childhood (ALSPAC study): an observational cohort study. Lancet. 2007 Feb 17;369(9561):578-85.
Langdon JH. Has an aquatic diet been necessary for hominin brain evolution and functional development? Br J Nutr. 2006 Jul;96(1):7-17.
Johansson C, Castoldi AF, Onishchenko N, Manzo L, Vahter M, Ceccatelli S. Neurobehavioural and molecular changes induced by methylmercury exposure during development. Neurotox Res. 2007 Apr;11(3-4):241-60)
Domingo JL, Bocio A. Levels of PCDD/PCDFs and PCBs in edible marine species and human intake: a literature review. Environ Int. 2007 Apr;33(3):397-405.
Cundiff DK, Lanou AJ, Nigg CR. Relation of omega-3 Fatty Acid intake to other dietary factors known to reduce coronary heart disease risk. Am J Cardiol. 2007 May 1;99(9):1230-3.
Burr ML, Ashfield-Watt PA, Dunstan FD, Fehily AM, Breay P, Ashton T, Zotos PC, Haboubi NA, Elwood PC. Lack of benefit of dietary advice to men with angina: results of a controlled trial. Eur J Clin Nutr. 2003 Feb;57(2):193-200.
Sacks FM, Stone PH, Gibson CM, Silverman DI, Rosner B, Pasternak RC. Controlled trial of fish oil for regression of human coronary atherosclerosis. HARP Research Group. J Am Coll Cardiol. 1995 Jun;25(7):1492-8.
Hooper L, Thompson RL, Harrison RA, Summerbell CD, Ness AR, Moore HJ, Worthington HV, Durrington PN, Higgins JP. Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ. 2006 Apr 1;332(7544):752-60.
Huston MC. The role of mercury and cadmium heavy metals in vascular disease, hypertension, coronary heart disease, and myocardial infarction. Altern Ther Health Med. 2007 Mar-Apr;13(2):S128-33.
Davidson MH, Hunninghake D, Maki KC, Kwiterovich PO Jr, Kafonek S. Comparison of the effects of lean red meat vs lean white meat on serum lipid levels among free-living persons with hypercholesterolemia: a long-term, randomized clinical trial. Arch Intern Med. 1999 Jun 28;159(12):1331-8.
Harris WS, Dujovne CA, Zucker M, Johnson B. Effects of a low saturated fat, low cholesterol fish oil supplement in hypertriglyceridemic patients. A placebo-controlled trial. Ann Intern Med. 1988 Sep 15;109(6):465-70.
Wilt TJ, Lofgren RP, Nichol KL, Schorer AE, Crespin L, Downes D, Eckfeldt J. Fish oil supplementation does not lower plasma cholesterol in men with hypercholesterolemia. Results of a randomized, placebo-controlled crossover study. Ann Intern Med. 1989 Dec 1;111(11):900-5.
Bellamy MF, McDowell IF, Ramsey MW, Brownlee M, Bones C, Newcombe RG, Lewis MJ. Hyperhomocysteinemia after an oral methionine load acutely impairs endothelial function in healthy adults. Circulation. 1998 Nov 3;98(18):1848-52.
Holdt B, Korten G, Knippel M, Lehmann JK, Claus R, Holtz M, Hausmann S. Increased serum level of total homocysteine in CAPD patients despite fish oil therapy. Perit Dial Int. 1996;16 Suppl 1:S246-9.
Robertson W. The effect of high animal protein intake on the risk of calcium stone-formation in the urinary tract. Clin Sci (Lond). 1979 Sep;57(3):285-8.
Dyerberg J, Bang HO. Haemostatic function and platelet polyunsaturated fatty acids in Eskimos. Lancet. 1979 Sep 1;2(8140):433-5.
Meydani SN, Lichtenstein AH, Cornwall S, Meydani M, Goldin BR, Rasmussen H, Dinarello CA, Schaefer EJ. Immunologic effects of national cholesterol education panel step-2 diets with and without fish-derived N-3 fatty acid enrichment. J Clin Invest. 1993 Jul;92(1):105-13.
Stripp C, Overvad K, Christensen J, Thomsen BL, Olsen A, Moller S, Tjonneland A. Fish intake is positively associated with breast cancer incidence rate. J Nutr. 2003 Nov;133(11):3664-9. Cancer Res. 1998 Aug 1;58(15):3312-9
Klieveri L, Fehres O, Griffini P, Van Noorden CJ, Frederiks WM. Promotion of colon cancer metastases in rat liver by fish oil diet is not due to reduced stroma formation. Clin Exp Metastasis. 2000;18(5):371-7.
Hendra TJ, Britton ME, Roper DR, et al. Effects of fish oil supplements in NIDDM subjects. Controlled study. Diabetes Care. 1990 Aug;13(8):821-9.
Olsen SF, Osterdal ML, Salvig JD, Weber T, Tabor A, Secher NJ. Duration of pregnancy in relation to fish oil supplementation and habitual fish intake: a randomised clinical trial with fish oil. Eur J Clin Nutr. 2007 Feb 7;
Olsen SF, Hansen HS, Sorensen TI, Jensen B, Secher NJ, Sommer S, Knudsen LB. Intake of marine fat, rich in (n-3)-polyunsaturated fatty acids, may increase birthweight by prolonging gestation. Lancet. 1986 Aug 16;2(8503):367-9.
Foran JA, Carpenter DO, Hamilton MC, Knuth BA, Schwager SJ. Risk-based consumption advice for farmed Atlantic and wild Pacific salmon contaminated with dioxins and dioxin-like compounds. Environ Health Perspect. 2005 May;113(5):552-6.)
ll JG, Henderson RJ, Tocher DR, McGhee F, Dick JR, Porter A, Smullen RP, Sargent JR. Substituting fish oil with crude palm oil in the diet of Atlantic salmon (Salmo salar) affects muscle fatty acid composition and hepatic fatty acid metabolism. J Nutr. 2002 Feb;132(2):222-30.
Lund V, Mejdell CM, Rocklinsberg H, Anthony R, Hastein T. Expanding the moral circle: farmed fish as objects of moral concern. Dis Aquat Organ. 2007 May 4;75(2):109-18.
Committee on the Toxicological Effects of Methylmercury, National Research Council. Toxicological effects of methylmercury. Washington, DC: National Academy Press; 2000.
Bender M. Letter to FDA about better protecting women and children from exposure to mercury, February 24, 2004.
Hu FGB, Bronner L, Willett WC, et al. Fish and omega-3a fatty acid intake and risk of coronary heart disease in women. JAMA. 2002;287:1815-1821.
Siscovick DS, Raghunathan TE, King I, et al. Dietary intake of long-chain n-3 polyunsaturated fatty acids and the risk of primary cardiac arrest. Am J Clin Nutr. 2000;71:208S-212S.
Guallar E, Sanz-Gallardo MI, van’t Veer P, et al. Heavy Metals and Myocardial Infarction Study Group. Mercury, fish oils, and the risk of myocardial infarction. N Engl J Med. 2002;347:1747-1754.
Salonen JT, Seppanen K, Nyyssonen K, et al. Intake of mercury from fish, lipid peroxidation, and the risk of myocardial infarction and coronary, cardiovascular, and any death in eastern Finnish men. Circulation. 1995;91:645-655.
Virtanen JK, Voutilainen S, Rissanen TH, et al. Mercury, fish oils, and risk of acute coronary events and cardiovascular disease, coronary heart disease, and all-cause mortality in men in eastern Finland. Arterioscler Thromb Vasc Biol. 2005;25(1):228-233.
United States Environmental Protection Agency. 2004 national listing of fish and wildlife advisories, fact sheet, September 2005.
United States Environmental Protection Agency. Dioxins.
United States Environmental Protection Agency. Persistent bioaccumulative and toxic (PBT) chemical program: dioxins and furans. April 2003.
Mahaffey KR. Methylmercury: epidemiology update. Presentation at the national forum on contaminants in fish, San Diego, January 28, 2004.
Centers for Disease Control and Prevention (CDC). Trends in intake of energy and macronutrients—United States, 1971-2000. MMWR Morb Mortal Wkly Rep. 2004;53(4):80-82.
Knight EL, Stampfer MJ, Hankinson SE, Spiegelman D, Curhan GC. The impact of protein intake on renal function decline in women with normal renal function or mild renal insufficiency. Ann Int Med. 2003;138:460-467.
Feskanich D, Willett WC, Stampfer MJ, Colditz GA. Protein consumption and bone fractures in women. Am J Epidemiol. 1996;143:472-479.
Gin H, Rigalleau V, Aparicio M. Lipids, protein intake, and diabetic nephropathy. Diabetes Metab. 2000;26:45-53.
Allen NE, Sauvaget C, Roddam AW, et al. A prospective study of diet and prostate cancer in Japanese men. Cancer Causes Control. 2004;15(9):911-920.
DC Division of Bacterial and Mycotic Diseases. Disease listing: marine toxins.
Sacks FM, Castelli WP, Donner A, Kass EH. Plasma lipids and lipoproteins in vegetarians and controls. N Engl J Med. 1975;292:1148-1152.
Barnard ND, Scialli AR, Bertron P, Hurlock D, Edmonds K, Talev L. Effectiveness of a low-fat vegetarian diet in altering serum lipids in healthy premenopausal women. Am J Cardiol. 2000;85:969-972.
Ornish D, Brown SE, Scherwitz LW. Can lifestyle changes reverse coronary heart disease? Lancet. 1990;336:129-133.
Esselstyn CB Jr, Ellis SG, Medendorp SV, Crowe TD. A strategy to arrest and reverse coronary artery disease: a 5-year longitudinal study of a single physician’s practice. J Fam Pract. 1995;41:560-568.
Raitt MH, Connor WE, Morris C, et al. Fish oil supplementation and risk of ventricular tachycardia and ventricular fibrillation in patients with implantable defibrillators: a randomized controlled trial. JAMA. 2005;293(23):2884-2891.
Odeleye OE, Watson RR. Health implications of the n-3 fatty acids. Am J Clin Nutr. 1991;53:177-178.
Kinsella JE. Reply to O Odeleye and R Watson. Am J Clin Nutr. 1991;53:178.
Hunter JE. n-3 Fatty acids from vegetable oils. Am J Clin Nutr. 1990;51:809-814.
Mantzioris E, James MJ, Gibson RA, Cleland LG. Dietary substitution with an alphalinolenic acid-rich vegetable oil increases eicosapentaenoic acid concentrations in tissues. Am J Clin Nutr. 1994;59:1304-1309.
S. J. Petre, D. K. Sackett, D. D. Aday. Do national advisories serve local consumers: An assessment of mercury in economically important North Carolina fish. J. Environ. Monit. 2012 14(5):1410 – 1416.
P. Grandjean, J. E. Henriksen, A. L. Choi, M. S. Petersen, C. Dalgaard, F. Nielsen, P. Weihe. Marine food pollutants as a risk factor for hypoinsulinemia and type 2 diabetes. Epidemiology 2011 22(3):410 – 417.
D.-H. Lee, I.-K. Lee, K. Song, M. Steffes, W. Toscano, B. A. Baker, D. R. Jacobs Jr. A strong dose-response relation between serum concentrations of persistent organic pollutants and diabetes: Results from the National Health and Examination Survey 1999-2002. Diabetes Care 2006 29(7):1638 – 1644.
A. Wallin, D. Di Giuseppe, N. Orsini, P. S. Patel, N. G. Forouhi, A. Wolk. Fish consumption, dietary long-chain n-3 fatty acids, and risk of type 2 diabetes: Systematic review and meta-analysis of prospective studies. Diabetes Care 2012 35(4):918 – 929.
R. F. White, C. L. Palumbo, D. A. Yurgelun-Todd, K. J. Heaton, P. Weihe, F. Debes, P. Grandjean. Functional MRI approach to developmental methylmercury and polychlorinated biphenyl neurotoxicity. Neurotoxicology 2011 32(6):975 – 980.
M. J. Zeilmaker, J. Hoekstra, J. C. H. van Eijkeren, N. de Jong, A. Hart, M. Kennedy, H. Owen, H. Gunnlaugsdottir. Fish consumption during child bearing age: a quantitative risk-benefit analysis on neurodevelopment. Food Chem Toxicol. 2013 54:30-34.
D. A. Axelrad, D. C. Bellinger, L. M. Ryan, T. J. Woodruff. Dose-response relationship of prenatal mercury exposure and IQ: An integrative analysis of epidemiologic data. Environ. Health Perspect. 2007 115(4):609 – 615.
E. Oken, A. L. Choi, M. R. Karagas, K. Mariën, C. M. Rheinberger, R. Schoeny, E. Sunderland, S. Korrick. Which fish should I eat? Perspectives influencing fish consumption choices. Environ. Health Perspect. 2012 120(6):790 – 798.
I. B. Cace, A. Milardovic, I. Prpic, R. Krajina, O. Petrovic, P. Vukelic, Z. Spiric, M. Horvat, D. Mazej, J. Snoj. Relationship between the prenatal exposure to low-level of mercury and the size of a newborn’s cerebellum. Med. Hypotheses 2011 76(4):514 – 516.
M. R. Karagas, A. L. Choi, E. Oken, M. Horvat, R. Schoeny, E. Kamai, W. Cowell, P. Grandjean, S. Korrick. Evidence on the human health effects of low-level methylmercury exposure. Environ. Health Perspect. 2012 120(6):799 – 806.
J. J. Strain, P. W. Davidson, M. P. Bonham, E. M. Duffy, A. Stokes-Riner, S. W. Thurston, J. M. W. Wallace, P. J. Robson, C. F. Shamlaye, L. A. Georger, J. Sloane-Reeves, E. Cernichiari, R. L. Canfield, C. Cox, L. S. Huang, J. Janciuras, G. J. Myers, T. W. Clarkson. Associations of maternal long-chain polyunsaturated fatty acids, methyl mercury, and infant development in the Seychelles Child Development Nutrition Study. Neurotoxicology 2008 29(5):776 – 782.
A. M. Lando, Y. Zhang. Awareness and knowledge of methylmercury in fish in the United States. Environ. Res. 2011 111(3):442 – 450.
P. A. Olsvik, H. Amlund, B. E. Torstensen. Dietary lipids modulate methylmercury toxicity in Atlantic salmon. Food Chem. Toxicol. 2011 49(12):3258 – 3271.
M. Porta. Persistent organic pollutants and the burden of diabetes. Lancet 2006 368(9535):558-559.
B. Choi, L. Lapham, L. Amin-Zaki, T. Saleem. Abnormal neuronal migration, deranged cerebral cortical organization, and diffuse white matter astrocytosis of human fetal brain: a major effect of methylmercury poisoning in utero. J Neuropathol Exp Neurol. 1978 37(6):719-733.
S. B. Elhassani. The many faces of methylmercury poisoning. J Toxicol Clin Toxicol. 1982 19(8):875 – 906.
K. Yaginuma-Sakurai, K. Murata, M. Iwai-Shimada, K. Nakai, N. Kurokawa, N. Tatsuta, H. Satoh. Hair-to-blood ratio and biological half-life of mercury: Experimental study of methylmercury exposure through fish consumption in humans. J Toxicol Sci 2012 37(1):123 – 130.
D. McAlpine, S. Araki. Minamata disease: An unusual neurological disorder caused by contaminated fish. Lancet 1958 2(7047):629 – 631.
L Trasande, Y Lui. Reducing the staggering costs of environmental disease in children, estimated at $76.6 billion in 2008. Health Aff 2011 30(5): 863-870.
J. Julvez, F. Debes, P. Weihe, A .Choi, P. Grandjean. Sensitivity of continuous performance test (CPT) at age 14 years to developmental methylmercury exposure. Neurotoxicol Teritol 2010 32(6): 627-32.
Jenkins DJA, Wolever TM, Taylor RH, et al. Glycemic index of foods: a physiological basis for carbohydrate exchange. Amer J of Clin Nutr. 1981; 34(3): 362-366.
T Colin Campbell. The China Study – https://nutritionstudies.org/the-china-study/