Most adults in the UK consume less than the recommended 30g of dietary fibre a day, according to the NHS

Increasing the amount of fibre in your diet could help reduce your risk of developing dementia, new research suggests.

The study, published in the Nutritional Neuroscience journal, involved more than 3,700 healthy adults in Japan whose diets were surveyed for more than 15 years in the 1980s and 1990s. Their health was then monitored until 2020 to assess who went on to develop dementia.

Scientists at the University of Tsukuba found that those who had consumed the most daily fibre had the lowest rates of dementia, with those who had eaten the least fibre having the highest rates of the syndrome. The link was “more pronounced” in the case of soluble fibres, found in oats and beans, than insoluble fibres, found in whole grains and potatoes – although both are important for a balanced diet.

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Explaining that the reasons behind the link are currently not understood, lead author Professor Kazumasa Yamagishi said: “One possibility is that soluble fiber regulates the composition of gut bacteria. This composition may affect neuroinflammation, which plays a role in the onset of dementia.

“It’s also possible that dietary fiber may reduce other risk factors for dementia, such as body weight, blood pressure, lipids [fats], and glucose levels. The work is still at an early stage, and it’s important to confirm the association in other populations.”

The NHS recommends adults consume 30g of dietary fibre a day but most people in the UK fail to achieve this. Eating plenty of the carbohydrate has been linked with a lower risk of heart disease, stroke, type two diabetes and bowel cancer.

The most common cause of dementia in the UK is Alzheimer’s disease. Diet is just one of the risk factors – the others being old age, family history of the condition and untreated depression.

Most people need to increase their amount of dietary fibre to meet the daily recommendation of 30g, according to the NHS. This amount is lower for children under the age of 16.

Fibre should be consumed from “a variety of sources” to ensure a healthy, balanced diet. These include:

• Cereal – try plain wholewheat biscuits (such as Weetabix), plain shredded whole grain (such as Shredded Wheat) or porridge
• Bread – go for wholemeal or granary loaves
• Potatoes – keep the skins on (such as baked potatoes or boiled new potatoes)
• Pulses – add beans, chickpeas or lentils to stews
• Vegetables – get your five-a-day
• Fruit – mix it up with dried, fresh or canned fruits