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Recent evidence concerning the effects of dietary n-3 PUFA
In recent years, a considerable body of evidence has been presented from clinical trials regarding the possible beneficial effects of dietary n-3 polyunsaturated fatty acid (PUFA), especially of fish origin. This paper is an extensive review of the latest evidence regarding the potential effects of dietary n-3 PUFA in cardiovascular disease, considering not only risk factors and clinical outcomes, but also the molecular mechanisms involved.
Both finfish and shellfish are important sources of dietary n-3 PUFA, including eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid.
Although concerns have been raised regarding fish contaminants including mercury and dioxin, it is generally accepted that the benefits of regular fish consumption outweigh any risks.
Concerning cardiovascular risk factors, there is evidence that n-3 PUFA lowers plasma triglycerides, reduces resting heart rate and blood pressure, decreases thrombosis risk, and improves endothelial and autonomic function.
An increasing body of data suggest that n-3 PUFA may improve cardiac filling and myocardial efficiency.
Recent studies have suggested that n-3 PUFA may improve cardiac arrhythmia.
The molecular mechanisms of n-3 PUFA action are discussed including effects on cell and organelle membranes, electrophysiological effects, and the regulation of gene expression.
The sometimes conflicting evidence concerning the effects of n-3 PUFA on coronary heart disease-associated mortality and sudden cardiac death are reviewed. The weight of evidence is in favour of a reduction in mortality associated with n-3 PUFA consumption.
Available pre-clinical and clinical evidence concerning effects of n-3 PUFA on ischaemic stroke, atrial fibrillation, recurrent ventricular tachyarrhythmia, and congestive heart failure is discussed.
Current dietary guidelines recommend at least 2 servings of oily fish per week.
1Division of General Internal Medicine, Department of Medicine, Duke University Medical Center, Durham, NC, USA; 2Center for Health Services Research in Primary Care, Durham VA Medical Center, Durham, NC, USA; 3Center for Integrative Medicine, Duke University Medical Center, Durham, NC, USA; 4Department of Biostatistics, Duke University Medical Center, Durham, NC, USA; 5Department of Community and Family Medicine, Duke University Medical Center, Durham, NC, USA; 6Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA.
BACKGROUND: Integrative medicine is an individualized, patient-centered approach to health, combining a whole-person model with evidence-based medicine. Interventions based in integrative medicine theory have not been tested as cardiovascular risk-reduction strategies. Our objective was to determine whether personalized health planning (PHP), an intervention based on the theories and principles underlying integrative medicine, reduces 10-year risk of coronary heart disease (CHD).
METHODS: We conducted a randomized, controlled trial among 154 outpatients age 45 or over, with 1 or more known cardiovascular risk factors. Subjects were enrolled from primary care practices near an academic medical center, and the intervention was delivered at a university Center for Integrative Medicine. Following a health risk assessment, each subject in the intervention arm worked with a health coach and a medical provider to construct a personalized health plan. The plan identified specific health behaviors important for each subject to modify; the choice of behaviors was driven both by cardiovascular risk reduction and the interests of each individual subject. The coach then assisted each subject in implementing her/his health plan. Techniques used in implementation included mindfulness meditation, relaxation training, stress management, motivational techniques, and health education and coaching. Subjects randomized to the comparison group received usual care (UC) without access to the intervention. Our primary outcome measure was 10-year risk of CHD, as measured by a standard Framingham risk score, and assessed at baseline, 5, and 10 months. Differences between arms were assessed by linear mixed effects modeling, with time and study arm as independent variables.
RESULTS: Baseline 10-year risk of CHD was 11.1% for subjects randomized to UC (n=77), and 9.3% for subjects randomized to PHP (n=77). Over 10 months of the intervention, CHD risk decreased to 9.8% for UC subjects and 7.8% for intervention subjects. Based on a linear mixed-effects model, there was a statistically significant difference in the rate of risk improvement between the 2 arms (P=.04). In secondary analyses, subjects in the PHP arm were found to have increased days of exercise per week compared with UC (3.7 vs 2.4, P=.002), and subjects who were overweight on entry into the study had greater weight loss in the PHP arm compared with UC (P=.06).
CONCLUSIONS: A multidimensional intervention based on integrative medicine principles reduced risk of CHD, possibly by increasing exercise and improving weight loss.