Dietary interventions can affect serum lipid and lipoprotein levels in a favorable way, especially in reducing levels of total cholesterol, triglycerides, and low density lipoprotein-cholesterol, and in elevating high density lipoprotein-cholesterol. However, the available data are not clear with respect to the magnitude and direction of these changes. Therefore, it is with great difficulty that health professionals can achieve any degree of precision in prescribing the appropriate diet to reduce lipid and lipoprote in risk factors (for coronary artery diseases). Reviews of literature in this area of research have used the traditional approach, that is, chronologically and/or categorically arranging and describing the studies. These traditional research reviews usually result in subjective and unreliable conclusions. Consequently, the relationships among such variables as length of dietary intervention, dietary composition, and body weight changes and the way in which they all contribute to changes in serum lipid and lipoprotein levels remain unclear. As a result, there is a great need for research synthesis that will be statistical and technical as well as narrative and rhetorical to clarify these issues. To accomplish this, meta-analysis methodology will be used to integrate statistically the research findings dealing with the relationships between dietary interventions and changes in serum lipid and lipoprotein levels in humans. Meta-analysis allows for the statistical integration of separate research findings and the determination of the overall magnitude and direction of a given effect. The purposes of this proposed project are: (1) The statistical integration (meta-analysis) of existing research studies on the effects of dietary interventions on changes in serum lipid and lipoprotein levels. (2) The comparison of 3 experimental effects - dietary intervention, exercise intervention, and dietary & exercise intervention as to their relative and unique effects on serum lipid and lipoprotein levels. (3) To provide the scientific community with a clearer perspective of the contributions of dietary interventions to lipid and lipoprotein level changes. This will enable investigators to provide appropriate controls for the many variables that interest with dietary interventions when designing future research. (4) To provide the health care community with findings and recommendations concerning optimal dietary prescriptions to reduce lipid and lipoprotein risk factors.
