Scientists from the University of Tsukuba have found that higher dietary fiber intake may be linked to a lower risk of developing dementia.
According to the National Institute on Aging, dementia refers to the loss of cognitive functioning—including thinking, memory, and reasoning—to a degree that interferes with a person’s daily life and activities.
In some cases, individuals with dementia may also experience emotional instability and personality changes.
Dietary fiber, also known as roughage, is the portion of plant-based food that cannot be fully digested by human enzymes. There are two main types of dietary fiber: soluble fiber and insoluble fiber. Both are found in plant-derived foods such as legumes, whole grains and cereals, vegetables, fruits, nuts, and seeds.
A diet rich in fiber has long been associated with numerous health benefits, including improved digestive health and a reduced risk of chronic diseases. Emerging research has also suggested that fiber intake may play a role in protecting brain health.
In the current study, researchers sought to determine whether dietary fiber intake was associated with a lower risk of disabling dementia—defined as dementia severe enough to require care under Japan’s national long-term care insurance system.
The research team analyzed data from the Circulatory Risk in Communities Study, which included 3,739 Japanese adults aged 40 to 64 years at the time of dietary assessment between 1985 and 1999. Participants’ fiber intake was estimated using the 24-hour dietary recall method. Cases of disabling dementia were tracked from 1999 through 2020.
Dementia cases were further classified according to whether participants had a history of stroke.
Over the 20-year follow-up period, 670 cases of disabling dementia were identified. The findings showed that higher total dietary fiber intake was associated with a lower risk of developing disabling dementia.
The association was particularly strong for soluble fiber intake and was observed primarily in cases of dementia without a prior history of stroke.
When examining specific fiber-containing foods, the researchers found that potato consumption—but not vegetables or fruits—showed a similar protective association.
Based on these findings, the researchers concluded that higher dietary fiber intake, especially soluble fiber, may be linked to a reduced risk of disabling dementia in the general Japanese population.
The study was published in Nutritional Neuroscience and was conducted by Kazumasa Yamagishi and colleagues.
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