The low incidence of reported heart attacks and cardiovascular-related deaths in Greenland Eskimos and the Japanese has generated interest in the possible protective effect of their diet, which is made up primarily of fish and related marine foods. This paper reviews the current evidence for reducing the risk of cardiovascular disease with fish-oil supplementation, and discusses related clinical data to support the mechanisms proposed. Included is evidence that fish oil can lower certain serum lipid levels, prolong bleeding time, and reduce systolic blood pressure when consumed in moderately large doses. Information on safety and side effects is also presented, such as a possible increase in serum cholesterol levels and annoying side effects that may severely limit widespread use of this food supplement. Presently it remains unanswered whether fish oil should be recommended as a dietary supplement for the prevention and/or treatment of hypercholesterolemia and associated coronary artery disease. Further research is required to demonstrate a clear reduction in cardiovascular mortality before a uniform recommendation can be made.
KromannNGreenA.Epidemiological studies in the Upernavik district, Greenland.Acta Med Scand1980; 205: 401–6.
2.
PhillipsonBERothrockDWConnorWEHarrisWSIllingworthR.Reduction of plasma lipids, lipoproteins, and apoproteins by dietary fish oils in patients with hypertriglyceridemia.N Engl J Med1985; 312: 1210–6.
3.
KeysA.Coronary heart disease in seven countries.Circulation1970; 41: 1162–79.
4.
BangHODyerbergJ.Plasma lipids and lipoproteins in Greenlandic west coast Eskimos.Acta Med Scand1972; 192: 85–94.
5.
BangHODyerbergJ.Lipid metabolism and ischemic heart disease in Greenland Eskimos.Adv Nutr Res1980; 3: 1–22.
6.
KagawaYNishizawaMSuzukiMEicosapolyenoic acids of serum lipids of Japanese islanders with low incidence of cardiovascular diseases.J Nutr Sci Vitaminol (Tokyo)1982; 28: 441–53.
7.
BRAEKKANOR.Health aspects of fish in the human diet. In: RajkiSBruceA, eds. Food production, nutrition, health.Budapest: Adakemiai Kiado, 1983: 43–51.
8.
KromhoutDBosschieterEBDe Lezenne CoulanderC.The inverse relation between fish consumption and 20-year mortality from coronary heart disease.N Engl J Med1985; 312: 1205–9.
9.
1987 Heart facts.Dallas, TX: American Heart Association, 1986: 1–7.
10.
SokolowMMcilroyMB.Clinical cardiology.3rd ed.Los Altos, CA: Lange Medical Publications, 1981: 131–7.
KannelWBMcgeeDGordonT.A general cardiovascular risk profile: the Framingham study.Am J Cardiol1976; 38: 46–51.
13.
AHA committee report-risk factors and coronary disease.Circulation1980; 62:450A–5A.
14.
ConnorWEConnorSL.The dietary treatment of hyperlipidemia: rationale, technique and efficacy.Med Clin North Am1982; 66: 485–518.
15.
ShekelleRBShryockAMPaulODiet, serum cholesterol, and death from coronary heart disease.N Engl J Med1981; 304: 65–70.
16.
GrundySM.Hyperlipoproteinemia: metabolic basis and rationale for therapy.Am J Cardiol1984; 54: 20C–6C.
17.
Lipid Research Clinics Program.The lipid research clinics coronary primary prevention trial results. I. Reduction in incidence of coronary heart disease.JAMA1984; 251:351–64.
18.
Lipid Research Clinics Program.The lipid research clinics coronary primary prevention trial results. II. The relationship of reduction in incidence of coronary heart disease to cholesterol lowering.JAMA1984; 251:365–74.
GordonTCastelliWPHjortlandMCHigh density lipo-protein as a protective factor against coronary heart disease: the Framingham study.Am J Med1977; 62: 707–14.
21.
BangHODyerbergJHjerneN.The composition of food consumed by Greenland Eskimos.Acta Med Scand1976; 200: 69–73.
22.
Fish oil for the heart.Med Lett Drugs Ther1987; 29:7–9.
23.
HepburnFNExlerJWeihrauchJL.Provisional tables on the content of omega-3 fatty acids and other fat components of selected foods.J Am Diet Assoc1986; 86: 788–93.
24.
LandsWE.Fish and human health.New York: Academic Press, 1986: 136–48.
25.
NestelPJConnorWEReardonMRConnorSWongSBostonR.Suppression by diets rich in fish oil of very low density lipoprotein production in man.J Clin Invest1984; 74: 82–9.
HarrisWSConnorWEIllingworthDRFosterDM.The mechanism of the hypotriglyceridemic effect of dietary omega-3 fatty acids in man (abstract).Clin Res1984; 32: 560A.
28.
HarrisWSConnorWEMcmurryMP.The comparative reductions of the plasma lipids and lipoproteins by dietary polyunsaturated fats: salmon oil vs. vegetable oils.Metabolism1983; 32: 179–84.
29.
ConnorWELinDSHarrisWS.A comparison of dietary polyunsaturated ω-6 and ω-3 fatty acids in humans: effects upon plasma lipids, lipoproteins and sterol balance (abstract).Arteriosclerosis1981; 1: 363a.
30.
GilmanAGGoodmanLGilmanA, eds. Goodman and Gilman's the pharmacological basis of therapeutics.6th ed.New York: Macmillan, 1980: 668–72.
31.
FisherSWeberPC.Prostaglandin I3 is formed in vivo in man after dietary eicosapentaenoic acid.Nature1984; 307: 165–8.
32.
WhiteASmithEHandlerP.Principles of biochemistry.6th ed.New York: McGraw-Hill, 1978: 594–5, 637–40.
33.
NeedlemanPRazAMinklesMSFerrendelliJASprecherH.Triene prostaglandins: prostacyclin and thromboxane biosynthesis and unique biological properties.Proc Natl Acad Sci USA1979; 76: 944–8.
34.
DyerbergJBangHOStoffersenEMoncadaSVaneJR.Eicosapentaenoic acid and prevention of thrombosis and atherosclerosis?Lancet1978; 2: 117–9.
35.
LorenzRSpenglerUFischerSDuhmJWeberPC.Platelet function, thromboxane formation and blood pressure control during supplementation of the western diet with cod-liver oil.Circulation1983; 67: 504–11.
36.
SiessWRothPSchererBKurzmanIBohligBWeberPC.Platelet-membrane fatty acids, platelet aggregation, and thromboxane formation during a mackerel diet.Lancet1980; 1: 441–4.
37.
SandersTAVickersMHainesAP.Effect on blood lipids and haemostasis of a supplement of cod-liver oil, rich in eicosapen-taenoic and docosahexaenenoic acids, in healthy young men.Clin Sci1981; 61: 317–24.
38.
NagakawaYOrimoHHarasawaMMoritaIYashiroKMurotaS.Effect of eicosapentaenoic acid on the platelet aggregation and composition of fatty acid in man.Atherosclerosis1983; 47: 71–5.
39.
KnappHRReillyIAAlessandriniPFitzgeraldGA.In vivo indexes of platelet and vascular function during fish-oil administration in patients with atherosclerosis.N Engl J Med1986; 314: 937–42.
40.
SandersTABRoshanaiF.The influence of different types of ω3 polyunsaturated fatty acids on blood lipids and platelet function in healthy volunteers.Clin Sci1983; 64: 91–9.
41.
MielkeCHJrRamosJCBrittonAFH.Aspirin as an antiplatelet agent: template bleeding time as a monitor of therapy.Am J Clin Pathol1973; 59: 236–42.
42.
LeeTHHooverRLWilliamsJDEffect of dietary enrichment with eicosapentaenoic and docosahexaenoic acids on in vitro neutrophil and monocyte leukotriene generation and neutrophil function.N Engl J Med1985; 312: 1217–24.
43.
FaggiottoARossRHarkerL.Studies of hypercholesterolemia in the nonhuman primate.Arteriosclerosis1984; 4: 323–40.
44.
MoncadaSFlowerRVaneJ.Prostaglandins, prostacyclin, thromboxane A2, and leukotrienes. In: GilmanAGoodmanLRallTMuradF, eds. Goodman and Gilman's the pharmacological basis of therapeutics.7th ed.New York: Macmillan, 1985: 660–73.
45.
SingerPWirthMVoigtSZimontkowskiWGodickeWHeineH.Clinical studies on lipid and blood pressure lowering effect of eicosapentaenoic acid-rich diet.Biomed Biochim Acta1984; 43: S421–5.
46.
NomsPGJonesCJNWestonMJ.Effect of dietary supplementation with fish oil on systolic blood pressure in mild essential hypertension.Br Med J1986; 293: 104–5.
