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Studies on Omega-3 for Heart Disease
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- Dewailly E, Blanchet C, Gingras S,
Lemieux S, Holub BJ. Public Health Research Unit, CHUL Research Center, Centre
Hospitalier Universitaire de Quebec, Quebec, QC, Can. Cardiovascular disease risk factors and omega-3 fatty acid status in the
adult population of James Bay Cree. American Journal of Clinical
Nutrition 2002; 76(1): 85-92.
Abstract: Background: Canadian native populations, which traditionally
consume large amounts of fish, have lower rates of mortality from
heart disease than do Canadian nonnative populations, which have low
fish intakes. Fish oils rich in n-3 fatty acids may have a
protective effect against cardiovascular disease (CVD) risk factors. Objectives: The purposes were to examine the profile of plasma
phospholipid concentrations of the n-3 fatty acids eicosapentaenoic acid
(EPA) and docosahexaenoic acid (DHA) among James Bay Cree and to
verify the relation between these concentrations and CVD risk
factors. Design: The study population consisted of 917 subjects aged
18-74 y who participated in the 1991 Santé Québec Health
Survey. Data were obtained through home interviews and clinic
visits. Plasma samples were analyzed for phospholipid fatty acid
composition. Results: The mean fish consumption on the day before the survey
was 60 g among the adult Cree population. Expressed as a percentage of
total fatty acids, relative concentrations of EPA and DHA were 0.65%
and 2.80%, respectively. n-3 Fatty acids were higher among coastal
residents than among inland residents. A positive association was
observed between plasma HDL and n-3 fatty acids. EPA and EPA+DHA
were inversely associated with triacylglycerols. Among subjects aged
50-74 y, an inverse association between EPA and EPA:AA and total:HDL
cholesterol was observed.
Conclusions: n-3 Fatty acids may favorably influence some
CVD risk factors. The Cree population must be encouraged to maintain
their traditional fish-based diet, which may be one of the factors protecting
them against mortality from CVD.
- Kromhout D, Bosschieter EB, Coulander
CDL. The inverse relation between fish
consumption and 20-year mortality from coronary heart disease. N. Engl.
J. Med. 1985; 312: 1205-1209.
Abstract: The low death rate from coronary heart disease
among the Greenland Eskimos has been ascribed to their high fish consumption.
We therefore decided to investigate the relation between fish consumption and
coronary heart disease in a group of men in the town of Zutphen, the
Netherlands. Information about the fish consumption of 852 middle-aged men
without coronary heart disease was collected in 1960 by a careful dietary
history obtained from the participants and their wives. During 20 years of
follow-up 78 men died from coronary heart disease. An inverse dose-response
relation was observed between fish consumption in 1960 and death from coronary
heart disease during 20 years of follow-up. This relation persisted after
multiple logistic-regression analyses. Mortality from coronary heart disease
was more than 50 per cent lower among those who consumed at least 30 g of fish
per day than among those who did not eat fish. We conclude that the consumption
of as little as one or two fish dishes per week may be of preventive value in
relation to coronary heart disease.
- Shekell RB, Missell LV, Paul O et al. Fish consumption and mortality from coronary heart disease. N.
Engl. J. Med. 1985; 313: 820.
- Norell SE, Ahlbom A, Feychting M et al. Fish consumption and mortality from coronary heart disease. BMJ
1986; 293: 426.
- Knapp HR, FitzGerald GA. The antihypertensive effects of fish oil: a
controlled study of polyunsaturated fatty acid supplements in essential
hypertension. N. Engl. J. Med. 1989; 320: 1037-1043.
Abstract: Both n-3 and
n-6 polyunsaturated fats have been suggested to lower blood pressure, an effect
ascribed to altered biosynthesis of eicosanoids. To test these hypotheses, we
studied blood pressure and eicosanoid production during supplementation of
dietary fat for four weeks in 32 men with mild essential hypertension.
Supplementation was preceded and followed by four-week run-in and recovery
periods. Groups of eight subjects received either 10 ml or 50 ml of fish oil (3
or 15 g of n-3 fatty acids) daily, 50 ml of safflower oil (39 g of n-6 fatty
acids), or 50 ml of a mixture of oils that approximated the types of fat
present in the American diet. The biosynthesis of eicosanoids was assessed by
the measurement of urinary metabolites. Blood pressure decreased in the men who
received the high dose of fish oil (systolic pressure by a mean of 6.5 mm Hg [P
less than 0.03] and diastolic pressure by 4.4 mm Hg [P less than 0.015]), but
not in the other groups. Although the formation of vasodilatory prostacyclins
(prostaglandins I2 and I3) increased initially, this increase was not
maintained as blood pressure fell. The level of thromboxane A2 metabolites
fell; metabolites of thromboxane A3 were detected in the groups receiving fish
oil. The formation of prostaglandin E2 increased during supplementation with
safflower oil and tended to decrease with fish oil; no prostaglandin E3
metabolite was detected. Our data indicate that high doses of fish oil can
reduce blood pressure in men with essential hypertension. However, the clinical
usefulness and safety of fish oil in the treatment of hypertension will require
further study.
- Radack K, Deck C, Huster G. The effects of low doses of omega-3 fatty
acid supplementation on blood pressure in hypertensive subjects: a randomized
controlled trial. Arch. Intern. Med. 1991; 151: 1173-1180.
- De Caterina R, Madonna R. Antiarrhythmia effects of omega-3 fatty
acids. A review. Italian Heart Journal: Official Journal of the
Italian Federation of Cardiology 2002; 3(3 Suppl.): 297-308.
- Appel LJ, Miller ER 3rd,
Seidler AJ, Whelton PK. Does
supplementation of diet with 'fish oil' reduce blood pressure? A meta-analysis
of controlled clinical trials. Archives of Internal Medicine 1993;
153(12): 1429-1438.
- GISSI-Prevenzione Investigators. Dietary supplementation with omega-3
polyunsaturated fatty acids and vitamin E after myocardial infarction: results
of the GISSI-Prevenzione trial. Lancet 1999; 354: 447-455.
Abstract: Background There is conflicting evidence
on the benefits of foods rich in vitamin E (α-tocopherol), n-3 polyunsaturated
fatty acids (PUFA), and their pharmacological substitutes. We investigated the
effects of these substances as supplements in patients who had myocardial
infarction. Methods From October, 1993, to
September, 1995, 11 324 patients surviving recent (≤3 months) myocardial
infarction were randomly assigned supplements of n-3 PUFA (1 g daily, n=2836),
vitamin E (300 mg daily, n=2830), both (n=2830), or none (control, n=2828) for
3·5 years. The primary combined efficacy endpoint was death, non-fatal
myocardial infarction, and stroke. Intention-to-treat analyses were done
according to a factorial design (two-way) and by treatment group (four-way). Findings Treatment with n-3 PUFA, but
not vitamin E, significantly lowered the risk of the primary endpoint
(relativerisk decrease 10% [95% CI 1-18] by two-way analysis, 15% [2-26] by
four-way analysis). Benefit was attributable to a decrease in the risk of death
(14% [3-24] two-way, 20% [6-33] four-way) and cardiovascular death (17% [3-29]
two-way, 30% [13-44] four-way). The effect of the combined treatment was
similar to that for n-3 PUFA for the primary endpoint (14% [1-26]) and for
fatal events (20% [5-33]). Interpretation Dietary supplementation with
n-3 PUFA led to a clinically important and satistically significant benefit.
Vitamin E had no benefit. Its effects on fatal cardiovascular events require
further exploration.
- Kromann N, Green A. Epidemiologic studies in the Upernavik
district, Greenland: incidence of some chronic diseases 1950-1974. Acta.
Med. Scand. 1980; 208: 401-406.
- Bang
HO, Dyerberg J, Horne N. The
composition of food consumed by Greenland Eskimos. Acta. Med. Scand.
1976; 200: 69-73.
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