Authors: Dagfinn Aune, Abhijit Sen, Teresa Norat, Elio Riboli
Journal: European Journal of Nutrition
Year: 2020
Volume: 59
Pages: 421–432
DOI: https://doi.org/10.1007/s00394-019-01967-w
Study at a glance
| Study type | Systematic review and meta-analysis |
| Number of studies | Five prospective cohort studies |
| Participants | 865,829 participants with 19,282 cases |
| Population studied | Adults from Europe and the United States |
| Intervention or approach studied | Dietary fibre intake, including total fibre, cereal fibre, fruit fibre, and vegetable fibre |
| Comparison group | Lower fibre intake levels |
| Follow-up duration | Varied across studies, ranging from 4 to 16.8 years |
| Main outcome(s) | Incidence of diverticular disease |
Why was this study done?
Diverticular disease is far more common in high-income countries than in low-income countries, with some populations showing more than 20 to 40 times the incidence compared to low-risk groups. In the United States, around 65% of adults will develop the condition by age 80.
Migration studies and temporal trends suggest that lifestyle factors, particularly diet, play an important role. Diverticular disease has been linked to low physical activity, overweight and obesity, smoking, and use of certain medications such as non-steroidal anti-inflammatory drugs.
Several previous studies have suggested that high dietary fibre intake may lower risk, but the dose relationship and effects of different fibre types have varied. Aune and colleagues conducted this systematic review and meta-analysis to bring together all available evidence from prospective studies and clarify the relationship between fibre intake and diverticular disease.
How was the study performed?
The researchers searched PubMed and Embase up to August 2018 to identify all relevant prospective studies examining the link between dietary fibre intake and diverticular disease.
They combined results using established statistical methods to estimate the overall association. The analysis examined total dietary fibre intake as well as fibre from different food sources, including cereals, fruit, and vegetables.
The authors examined whether there was a dose relationship between fibre intake and risk, and tested whether the relationship was linear or whether the effect changed at different intake levels. They carried out additional analyses looking at different study characteristics and repeated the analysis after excluding one study at a time to assess result reliability.
What did the researchers find?
The meta-analysis included five cohort studies with more than 19,000 cases of diverticular disease and over 865,000 participants.
For every 10 grams per day increase in dietary fibre intake, there was a 26% reduction in risk of diverticular disease. The relationship was linear, meaning that risk continued to fall with higher intakes. Compared to an intake of 7.5 grams per day, the authors reported a 23% reduction in risk at 20 grams per day, a 41% reduction at 30 grams per day, and a 58% reduction at 40 grams per day.
For specific fibre types, cereal fibre was associated with a 26% reduction in risk per 10 grams per day, and fruit fibre with a 44% reduction per 10 grams per day. For vegetable fibre, the authors did not find a clear association with risk.
There was no evidence of variation between studies in the analysis of total dietary fibre. For cereal fibre, there was a small increase in risk at very low intakes but a clear reduction at intakes between 15 and 30 grams per day.
The inverse association remained when analyses were stratified by sex, follow-up duration, geographic location, number of cases, and adjustment for potential confounding factors such as age, smoking, body weight, physical activity, diabetes, and meat intake.
What did the authors conclude?
The authors concluded that high dietary fibre intake may reduce the risk of diverticular disease. They reported that individuals consuming 30 grams of fibre per day had a 41% reduction in risk compared to those with low fibre intake.
The findings support public health recommendations to increase fibre intake. The authors noted that further studies are needed to better understand the role of different fibre types and to examine the link between fibre intake and diverticulitis, a complication involving inflammation.
The authors acknowledged some limitations, including possible residual confounding from other lifestyle factors and measurement error in assessing fibre intake. However, they noted that the association remained consistent across different subgroups and sensitivity analyses.
Key takeaways
- Higher dietary fibre intake was associated with a lower risk of diverticular disease across five large prospective studies.
- For every 10 grams per day increase in fibre intake, the authors reported a 26% reduction in risk.
- People consuming 30 grams of fibre per day had a 41% lower risk compared to those with low intakes, according to the analysis.
- Fibre from cereals and fruit were both linked to reduced risk, whilst the evidence for vegetable fibre was less clear.
- The findings support recommendations to increase fibre intake for prevention of diverticular disease.
This Scientific Publication Summary is an objective summary of the published study for personal and educational use. It does not constitute medical advice, endorsement of the intervention, or a recommendation to alter clinical practice.