Development of a Publicly Available, Comprehensive Database of Fiber and Health Outcomes: Rationale and Methods

Abstract

Background: Dietary fiber is a broad category of compounds historically defined as partially or completely indigestible plant-based carbohydrates and lignin with, more recently, the additional criteria that fibers incorporated into foods as additives should demonstrate functional human health outcomes to receive a fiber classification. Thousands of research studies have been published examining fibers and health outcomes.

Objectives: (1) Develop a database listing studies testing fiber and physiological health outcomes identified by experts at the Ninth Vahouny Conference; (2) Use evidence mapping methodology to summarize this body of literature. This paper summarizes the rationale, methodology, and resulting database. The database will help both scientists and policy-makers to evaluate evidence linking specific fibers with physiological health outcomes, and identify missing information.

Methods: To build this database, we conducted a systematic literature search for human intervention studies published in English from 1946 to May 2015. Our search strategy included a broad definition of fiber search terms, as well as search terms for nine physiological health outcomes identified at the Ninth Vahouny Fiber Symposium. Abstracts were screened using a priori defined eligibility criteria and a low threshold for inclusion to minimize the likelihood of rejecting articles of interest. Publications then were reviewed in full text, applying additional a priori defined exclusion criteria. The database was built and published on the Systematic Review Data Repository (SRDR™), a web-based, publicly available application.

Conclusions: A fiber database was created. This resource will reduce the unnecessary replication of effort in conducting systematic reviews by serving as both a central database archiving PICO (population, intervention, comparator, outcome) data on published studies and as a searchable tool through which this data can be extracted and updated.

Fig 1. Schematic Illustration of Fiber Types and Levels of Classification.

The figure is split into 3 panels (A-C) only to optimize space. Fibers are classified into groups (Level 1) and subgroups (Level 2) of physically related compounds. Isolated fibers, including some purified fibers in the form of commercially available supplements, are listed in Level 3 and food sources in Level 4. The dashed line in panel C is meant to indicate that RS4 could also be categorized with the other chemically synthesized fiber types. ^aalso referred to as maltodextrin (EEU, UK), indigestible dextrin (Asia, Japan), resistant dextrin (Brazil, UK), pyrodextrin.

Fig 2. Flow Diagram of Studies.