The study offers another reason why you may consider upping your fibre intake daily.
"Our findings provide convincing evidence for nutrition guidelines to focus on increasing dietary fibre and on replacing refined grains with whole grains". High-fibre intake is also associated with lower body weight and cholesterol, compared with lower intake of synthetic and extracted fibre.
The team from the University of Otago in New Zealand looked at 185 clinical trials and 58 studies carried out during the last four decades involving more than a million people.
Their analysis found up to a 30% reduction in deaths from all causes among those who consumed the most fibre.
"Our research indicates we should have at least 25g to 29g of fibre from foods daily, although most of us now consume less than 20g of fibre daily", said Dr Andrew Reynolds, lead author of the study.
Co-author professor Jim Mann said: "This study is essential as there is increased public confusion over what to base our meal choices on, and the impact our dietary choices have on our risk of certain diseases". Consuming 25g to 29g each day was adequate but the data suggest that higher intakes of dietary fibre could provide even greater protection.
United Kingdom nutrition guidelines since 2015 recommend a daily fibre intake of 30g, but only 9% of adults manage to reach this target.
The study also found that diets with a low glycaemic index and low glycaemic load provided limited support for protection against Type 2 diabetes and stroke only.
For every 8g increase of dietary fibre eaten per day, total deaths and incidences of coronary heart disease, type 2 diabetes and colorectal cancer decreased by 5-27 per cent. Protection against stroke, and breast cancer also increased.
"Fibre-rich whole foods that require chewing and retain much of their structure in the gut increase satiety and help weight control and can favourably influence lipid and glucose levels".