We always hear that we should eat more fiber. It is known to be vitally important for a healthy digestive system and also has cardiovascular benefits like lowering cholesterol. Today, evidence is emerging that fiber is also important for a healthy brain. In a new study published this month in the journal Nutritional neuroscienceresearchers in Japan have shown that a high fiber diet is associated with a reduced risk of developing dementia.
Dementia is a devastating disease that usually requires long-term care. We were interested in some recent research suggesting that dietary fiber could play a preventive role. We investigated this using data collected from thousands of adults in Japan for a large study that began in the 1980s..”
Kazumasa Yamagishi, Study Lead Author and Professor, University of Tsukuba
Participants completed surveys that assessed their food intake between 1985 and 1999. They were generally healthy and between the ages of 40 and 64. They were then followed from 1999 to 2020, and it was noted whether they had developed dementia requiring care.
The researchers divided the data, from a total of 3,739 adults, into four groups based on the amount of fiber in their diet. They found that groups that ate higher levels of fiber had a lower risk of developing dementia.
The team also looked at whether there were any differences for the two main types of fiber: soluble and insoluble fiber. Soluble fiber, found in foods such as oats and legumes, is important for beneficial bacteria that live in the gut and provides other health benefits. Insoluble fiber, found in whole grains, vegetables, and some other foods, is known to be important for gut health. The researchers found that the link between fiber intake and dementia was most pronounced for soluble fiber.
The team has some ideas about what might underlie the link between dietary fiber and dementia risk.
“The mechanisms are currently unknown but could involve the interactions that take place between the gut and the brain,” says Professor Yamagishi. “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 is also possible that dietary fiber reduces other risk factors for dementia, such as body weight, blood pressure, lipids and glucose levels.The work is still at an early stage, and it is important to confirm the association in other populations.
In many countries today, such as the United States and Australia, many people consume less fiber than recommended by nutritionists. By encouraging healthy eating habits high in dietary fibre, it may be possible to reduce the incidence of dementia.
Yamagishi, K. et al. (2022) Dietary fiber intake and risk of disabling dementia incident: the community circulatory risk study. Nutritional neuroscience. doi.org/10.1080/1028415X.2022.2027592.