AIM: To comprehensively review and quantitatively summarize results from intervention studies that examined the effects of intact cereal dietary fiber on parameters of bowel function. METHODS: A systematic literature search was conducted using PubMed and EMBASE. Supplementary literature searches included screening reference lists from relevant studies and reviews. Eligible outcomes were stool wet and dry weight, percentage water in stools, stool frequency and consistency, and total transit time. Weighted regression analyses generated mean change (± SD) in these measures per g/d of dietary fiber. RESULTS: Sixty-five intervention studies among generally healthy populations were identified. A quantitative examination of the effects of non-wheat sources of intact cereal dietary fibers was not possible due to an insufficient number of studies. Weighted regression analyses demonstrated that each extra g/d of wheat fiber increased total stool weight by 3.7 ± 0.09 g/d (P < 0.0001; 95%CI: 3.50-3.84), dry stool weight by 0.75 ± 0.03 g/d (P < 0.0001; 95%CI: 0.69-0.82), and stool frequency by 0.004 ± 0.002 times/d (P = 0.0346; 95%CI: 0.0003-0.0078). Transit time decreased by 0.78 ± 0.13 h per additional g/d (P < 0.0001; 95%CI: 0.53-1.04) of wheat fiber among those with an initial transit time greater than 48 h. CONCLUSION: Wheat dietary fiber, and predominately wheat bran dietary fiber, improves measures of bowel function.

The aim of this systematic review and meta-analysis was to assess the effects of β-fructan supplementation on bowel function in healthy volunteers and patients. The search process was based on the selection of publications listed in the Pubmed and EUPMC database until December 2017, plus two unpublished studies, to identify studies evaluating the impact of β-fructans on bowel movement and stool parameters. Forty-seven publications were selected for inclusion. Primary parameter was frequency of bowel movements, evaluated by the number of defecations per day during the study period. Secondary outcomes were stool consistency, stool dry and wet weights, and transit time. Short-chain (DP < 10) β-fructans contributed to increased stool frequency (0.36 defecation +/− 0.06 per day; p < 0.001), while no significant effect was reported with long-chain (DP ≥ 10) β-fructans (−0.03 +/− 0.11, p = 0.82). A minimal increase in stool wet weight was also statistically demonstrated with short-chain β-fructans. Moreover, the meta-analysis highlighted significant differences in stool consistency in contrast to fecal dry weight after β-fructan supplementation. This systematic review and meta-analysis indicates that short-chain β-fructan supplementation has a positive effect on bowel function by significantly increasing the frequency of bowel movements.

Background: Shifting toward more plant-based diets is promoted for health, environmental, and ethical reasons. However, the nutritional consequences of reducing animal-based foods, particularly across age groups with specific dietary needs, remain insufficiently understood. Methods: In this simulation study, we used dietary intake data from 3570 participants in the Dutch National Food Consumption Survey (2019–2021) to evaluate how replacing animal-based foods with plant-based alternatives affects the intake of protein, essential amino acids (EAAs), vitamins, and minerals across different age groups. Two substitution scenarios were modeled: a nutritionally conscious and a less conscious plant-based dietary pattern. Results: Total protein intake decreased in both scenarios, with the strongest reductions observed in elderly individuals (71–79 years). Vitamin intake, particularly B vitamins and vitamin A, declined in most age groups, and vitamin D remained chronically low. Mineral intake also decreased, notably for calcium, iron, iodine, selenium, and zinc, especially among women and adolescents. Conclusions: These results underscore the importance of dietary planning and targeted fortification when promoting plant-based eating patterns. Future research should refine bioavailability estimates and evaluate the long-term health effects of such dietary transitions across life stages.