A review which Cummings co-authored found that those who ate the most fibre showed a 15-30% reduced risk of mortality compared to those who ate the least. Sufficient fibre consumption, which the researchers say is about 30g per day, lowers the risk of coronary heart disease, stroke, type 2 diabetes and colon cancer – and translates as 13 fewer deaths per 1,000 people.
The greatest benefits were seen at 25-29g of fibre per day. To achieve that, you could incorporate fibre into every meal and snack, with portions of fruits or vegetables in each meal. A skin-on jacket of potato with baked beans followed by an apple will provide about 15.7g of fibre for instance. Snacking on nuts and seeds will also increase your intake – a handful of nuts (about 30g) contains 3.8g of fibre.
Key to this impact is fibre’s relationship to the gut microbiome.
As our gut bacteria digest fibre, beneficial byproducts are produced, including the short-chain fatty acids acetate, propionate and butyrate. It’s these metabolic products that provide critical energy for cells and are linked to significant reductions in mortality, explains Cummings.
Minding your meals: How fibre protects the brain
A high-fibre diet is also now believed to be particularly important for brain health, explains Scott. The presence of the fatty-acid butyrate helps maintain the lining of the gut, she says, thus reducing the risk of harmful substances entering the bloodstream and affecting the brain.