Reduce Your Risk of Dementia by Meeting Your Dietary Fiber Needs Each Day

Posted December 2022
Avocado, Edamame & Chili Oil on Corn Thins slices

Keeping your mind healthy for life is important to promote optimal quality of life. You may not have thought of the impact that your gut microbiome plays in contributing to your brain health. This includes your risk of developing dementia.

Dementia is defined by the Alzheimer’s Association as ‘a general term for loss of memory, language, problem-solving and other thinking abilities that are severe enough to interfere with daily life. Alzheimer's is the most common cause of dementia.’ With an aging population reducing the risk of dementia in society is significant. A new study holds potential exciting new strategies to reduce the risk of disabling dementia through achieving adequate dietary fiber in your diet each day.

Dietary fiber is a type of carbohydrate which is not digested in the small intestine and reaches your large intestine undigested. Dietary fiber then acts as the fuel for the health promoting microbes which live in your gut. Adults needs between 25-38 grams of dietary fiber a day for health.

Keeping your health promoting microbes well fed leads to a matrix of health benefits for your body. This includes keeping your immune system at an optimal level to promoting organ health such as brain health. A new study now adds another potential reason to meet your recommended dietary fiber needs each day, to reduce your risk of disabling dementia.

The study selected 3739 Japanese individuals aged between 40-64 years of age. Researchers used dietary surveys as well as a twenty-four-hour dietary recall to assess the fiber intake of each individual. The researchers reported any new disabling dementia prognosis between the years of 1990 to 2020.

Over the research period 670 new cases of disabling dementia was reported. Researchers found that the more fiber a person included in their diet the risk of disabling dementia was lower. This was specifically true for the type of fiber called soluble fiber. If you are a lover of potato there is some good news as the positive effects were seen in potatoes, but not for other vegetables or fruits.

The reasoning behind this positive association between dietary fiber with reduced risk of disabling dementia is proposed to be due to direct bidirectional link that your gut has to your brain. This is called the brain-gut axis. Ultimately, this direct link means that if your gut health is suboptimal the effects will be felt in your brain too.

Dietary fiber has additional benefits which may indirectly have a positive effect on your brain health and reduce your risk of disabling dementia. This includes promoting a healthy weight, blood pressure and blood sugar levels. Dietary fiber also promotes optimal cholesterol levels and may reduce your risk of type two diabetes and stroke.

Soluble fiber has been proposed to have a more positive effect on reducing your risk of disabling dementia due to the species of microbes it promotes. A species called Bacteroides is more abundant when more soluble fiber is included in the diet. In addition to this benefit, soluble fiber appears to reduce the type of inflammation in your brain which is linked to aging. This appears to be due to the positive effects of a short-chain fatty acid called butyrate. Butyrate is produced by the health promoting microbes in your gut when after they consume the soluble fiber.

To achieve your daily dietary fiber including meals with at least half or more of your plate a plant-based food is a smart lifestyle habit to include. Plant foods include wholegrains, and wholegrain containing foods like Corn Thins slices, legumes, beans, nuts, seeds, vegetables, and fruit. Aim for variety as optimal gut health is seen when you include at least 30 different plant foods a day.

Take home message: The role of your gut microbiome in promoting optimal health and wellbeing throughout your life is becoming increasingly evident. Providing the prebiotic fuel that your health promoting microbes need to stay alive is essential for your health. Another reason to add to the list of reasons to include enough dietary fiber each day is its potential link to reducing your risk of dementia in the future.



  1. Kazumasa Yamagishi, Koutatsu Maruyama, Ai Ikeda, Masanori Nagao, Hiroyuki Noda, Mitsumasa Umesawa, Mina Hayama-Terada, Isao Muraki, Chika Okada, Mari Tanaka, Rie Kishida, Tomomi Kihara, Tetsuya Ohira, Hironori Imano, Eric J. Brunner, Tomoko Sankai, Takeo Okada, Takeshi Tanigawa, Akihiko Kitamura, Masahiko Kiyama & Hiroyasu Iso (2022) Dietary fiber intake and risk of incident disabling dementia: the Circulatory Risk in Communities Study, Nutritional Neuroscience, DOI: 10.1080/1028415X.2022.2027592
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Ashleigh Felth…
Accredited Practising Dietitian
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