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Title:
Effects of dietary fiber from grains, fruits, vegetables and pulses on bowel function systematically reviewed
Authors:
Dr. Jan de Vries
Workcenter:
De Vries Nutrition Solutions
Background
Dietary fibres (DF) can differ substantially in their physio- chemical characteristics. As a consequence these differences between dietary fibres can influence health effects differently, including bowel function parameters differently.
Objective
A systematic review was conducted on the effects of dietary fibre on bowel function parameters in healthy individuals using a relational database enabling comparative and quantitative estimates.
Methods
Systematic search strategies for English papers were applied in PUBMED and EMBASE. Statistical analysis focused on dietary fibre from grains, fruits, pulses and vegetables. Weighted regression analysis took into account the number of subjects in each reported study. Analysis of transit time took into account initial transit time ≤ 48 hrs and > 48 hrs.
Table 1. Summary of Regression analysis of ∆ total stool wet weight per gram dietary fiber for food origin and fermentability (bold numbers: slope, italic numbers: intercept).
Cereal
Fruit
Vegetable
∆ Total stool wet weight (g/g DF)
Fermentable
1,3±0,1
0,5±3,3
(n=21)
0,3±0,4
18,6±4,7
(n=6)
2,9±0,5
-10,6±8,2
(n=14)
Non fermentable
3,4±0,1
6,2±1,5
(n=100) -
(n=1)
1,9±0,1
-6,0±3,0
(n=8)
Results
In total 146 publications were identified. For statistical analysis of the data interventions where categorized according to food origin and fermentability. Table 1 shows the number of observations per category of fibre and per parameter, showing for example that 1 gram non-fermentable cereal DF increases total stool wet weight with 3.4 g. Figure 2 demonstrates the effectiveness of fermentable and non-fermentable dietary fiber on total wet stool weight for all 4 food origins.
When initial transit time is delayed (>48hrs) dietary fiber reduces transit time with approximately 0,5 hrs or 30 min/g DF (figure 3).
Too few results were available for DF from pulses for a correct regression analysis.
Conclusions
Non-fermentable grain-based dietary fibres were most effective in increasing total stool wet weight.
DF are three times as effective on total fecal weight compared to fermentable fiber.
Dietary fibres from grains and from vegetables are comparably effective in reducing total transit time in individuals with a delayed initial transit time. Non-fermentable.
This study was sponsored by Kellogg Company