How much fibre do we really need? A major review of the evidence

What does the research say?

Pooling decades of research, this review found that people eating the most fibre had a 15–30% lower risk of dying early, and of heart disease, stroke, type 2 diabetes and bowel cancer, than people eating the least. The greatest benefits appeared at around 25–29 g a day or more — most UK adults eat less than 20 g.

The science

The authors combined prospective cohort studies (following people over time) with controlled trials that measured risk factors such as body weight, blood pressure and cholesterol.

Comparing the highest with the lowest fibre intakes, they observed consistent reductions across a range of outcomes. Dose-response analysis suggested that risk continued to fall as fibre increased beyond 25–29 g per day. Whole grains showed similar associations.

Key findings

Higher fibre intake was associated with 15–30% lower all-cause and cardiovascular mortality.
Lower incidence of coronary heart disease, stroke, type 2 diabetes and colorectal cancer.
Benefits appeared greatest at 25–29 g/day or more.
Trials showed improvements in body weight, systolic blood pressure and total cholesterol.

Limitations

Most outcome data are observational — high-fibre eaters may have healthier lifestyles overall.
Trials measured risk factors rather than disease events.
People with some digestive conditions may need a tailored approach to increasing fibre.

References

Reynolds A, Mann J, Cummings J, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019;393(10170):434–445. doi.org/10.1016/S0140-6736(18)31809-9
Scientific Advisory Committee on Nutrition (SACN). Carbohydrates and Health. 2015. www.gov.uk/government/publications/sacn-carbohydrates-and-health-report