paper. All citations were entered into the study’s bibliographic database, which at the conclusion of the study contained approximately 850 references to abstracts, journal articles, books, congressional reports, and conference proceedings.
The evidence reviewed was heterogeneous (i.e., the types of nutrition-based therapies varied as did the types of outcomes reported). The latter included both “clinical” outcome variables (e.g., number of hip fractures, hospital admissions) and “intermediate” outcome variables (e.g., bone mineral density, blood pressure). The vast majority of studies report the effects of nutrition-based therapy on intermediate outcomes. The committee also evaluated the full spectrum of nutrition-based therapies. For example, for common outpatient conditions such as hypertension, the therapies included behavioral interventions that involved counseling, feeding studies that controlled food intake, and trials of dietary supplements. Multidisciplinary interventions were also evaluated as long as there was a nutritional component to the program. The type of individuals who conducted the study interventions and thus provided the nutrition therapy was not uniform: whereas a registered dietitian provided the nutrition-based therapy in most instances, there were several studies in which other personnel (e.g., nurses) administered the intervention. The setting for interventions varied as well (e.g., outpatient versus home-based, group versus individual counseling).
Although research conducted among the elderly was of primary interest, evidence from studies in non-elderly population groups, as well as evidence from studies that covered a broad age range of individuals—both non-elderly and elderly—was also considered. In many instances, fewer studies were conducted in elderly population groups than in the non-elderly. In this setting, the committee considered studies in non-elderly populations as relevant to its deliberations as long as the evidence appeared consistent across the adult lifespan.
In preparing this report, the committee evaluated and then classified the type and quality of available evidence for each of the diseases or conditions under study. Several classification schemes are available (NIH, 1998; USPSTF, 1995; Yusuf et al., 1998). For this report, the committee adapted the approach used by the National Institutes of Health (NIH)