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Am J Clin Nutr. 2018 Mar 1;107(3):436-444. doi: 10.1093/ajcn/nqx082.

Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses.

Author information

National Research Council, Neuroscience Institute, Aging Branch, Padova, Italy.
Ambulatory of Clinical Nutrition, National Institute of Gastroenterology-Research Hospital, "Saverio de Bellis", Castellana Grotte, Italy.
Department of Neurosciences, University of Padova, Padova, Italy.
Department of Hygiene and Epidemiology, University of Ioannina Medical School, Ioannina, Greece.
Department of Epidemiology and Biostatistics and MRC-PHE Center for Environment, School of Public Health, Imperial College London, London, United Kingdom.
Department of Clinical and Experimental Sciences, Brescia University Medical School, Brescia, Italy.
CEINGE Biotecnologie Avanzate, Naples, Italy.
Division of Geriatrics and Nutritional Science, Washington University, St. Louis, MO.
Physiotherapy Department, South London and Maudsley National Health System Foundation Trust, London, United Kingdom.
Health Service and Population Research Department, Institute of Psychiatry, Psychology, and Neuroscience (IoPPN), King's College London, London, United Kingdom.
Faculty of Health, Social Care, and Education, Anglia Ruskin University, Chelmsford, United Kingdom.
Department of MRC-PHE Center for Environment, School of Public Health, Imperial College London, London, United Kingdom.



Several studies have suggested that higher consumption of dietary fiber is beneficial for a variety of health outcomes. However, many results have been inconclusive and, to our knowledge, there has been no attempt to systematically capture the breadth of outcomes associated with dietary fiber intake or to systematically assess the quality and the strength of the evidence on the associations of dietary fiber intake and different health outcomes or medical conditions.


The aim of this study was to describe the diverse health outcomes convincingly associated with dietary fiber consumption.


This was an umbrella review of systematic reviews with meta-analysis of observational studies. For each association, random-effects summary effect size, 95% CIs, and 95% prediction intervals were estimated. We also assessed heterogeneity, evidence for small-study effect, and evidence for excess significance bias. We used these metrics to evaluate the credibility of the identified evidence.


Our literature search identified 1351 abstracts. Of these, 18 meta-analyses including a total of 298 prospective observational studies and 21 outcomes were included. Outcomes studied included cancer and precancer lesions (n = 12), cardiovascular diseases (CVDs; n = 3), all-cause and specific-cause mortality (n = 4), type 2 diabetes (n = 1), and Crohn disease (n = 1). Overall, 6 (29%) of the 21 eligible outcomes reported highly significant summary results (P < 1 × 10-6); these included CVD and CVD mortality, coronary artery disease, pancreatic cancer, and gastric cancer. Overall, 3 of 21 (14%) outcomes presented convincing evidence (pancreatic cancer, CVD mortality, and all-cause mortality), but only CVD and all-cause mortality were based on prospective studies. Two other outcomes (10%), CVD and coronary artery disease, presented highly suggestive evidence based on prospective studies.


Our results support dietary recommendations that promote higher fiber intake as part of a healthy diet.

[Indexed for MEDLINE]

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