Dietary fatty acids, hemostasis, and cardiovascular disease risk

The cause of many myocardial infarctions is occlusive thrombosis, or a blood clot that stops blood flow in a coronary artery. Hemostasis involves a complex system of factors, which normally form and degrade blood clots, that work within a delicate balance. Emerging evidence suggests that some hemostatic factors, including factor VII, fibrinogen, and plasminogen activator inhibitor-1, are associated with increased risk for cardiovascular disease (CVD). Accumulating evidence suggests a relationship between dietary fatty acids and emerging hemostatic CVD risk factors, although much of this evidence is incomplete or conflicting. Dietary supplementation with marine n-3 fatty acids prolongs bleeding time and may decrease risk for thrombosis. Factor VII coagulant activity modestly decreases with reductions in saturated fatty acid (SFA) intake and thereby may contribute to the beneficial effects of low SFA diets. Large triglyceride-rich particles formed during postprandial lipemia can support the assembly and function of coagulation complexes and seem to play a role in the activation of factor VII, and thus may partially explain increased CVD risk associated with increased postprandial triglyceridemia. As our understanding of the role of dietary fatty acids and hemostasis evolves, it is likely that we will be able to make specific dietary recommendations to further decrease CVD risk. At this juncture, however, increasing marine n-3 fatty acids and decreasing certain SFAs are leading strategies to reduce hemostatic CVD risk factors. An array of dietary strategies that target multiple CVD risk factors could have a greater impact on CVD than a single risk factor intervention strategy.     

Environmental and policy interventions to promote physical activity

Background:Because most adults in industrialized countries do not meet physical activity guidelines, population-wide interventions are needed. Environmental and policy interventions are based on ecological models of behavior and have the potential to influence entire populations. Ecological models are particularly applicable to physical activity because the behavior must be done in specific physical settings. Cross-sectional data indicate that environmental and policy variables are associated with physical activity behaviors of young people and adults.Method: Seven published evaluations of environmental and policy interventions to increase physical activity were reviewed.Results: Two studies showed that placing signs encouraging stair use can be effective. Quasi-experimental evaluations provided limited evidence that broad environmental changes can be effective. Large-scale policy interventions are currently being conducted in several countries.Proposed Model: A model describing the development of policy and environmental interventions is proposed, in the hope of stimulating more research in this area. Advocacy or planning groups identify and work with agencies that control policies and environments that can be altered to increase physical activity. Educational and policy/environmental interventions are seen as complementary.Conclusion: Lack of conceptual models and the inherent difficulties of evaluation have hampered research on environmental and policy interventions. Further research is needed, and practitioners and researchers should work together to evaluate programs.