We are always hearing that we should eat more fiber. It is known to be crucial for a healthy digestive system and also has cardiovascular benefits such as lowering cholesterol. Now, evidence is emerging that fiber is also important for a healthy brain. In a new study published this month in the journal Dr Neuroscience of NutritionJapanese researchers have shown that a high-fiber diet is associated with a reduced risk of dementia.
“Dementia is a devastating disease that usually requires long-term care,” said lead study author Professor Kazumasa Yamagishi. “We were interested in some recent studies that suggested that dietary fiber may 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.”
Participants completed surveys assessing their dietary intake between 1985 and 1999. They were generally healthy and aged between 40 and 64 years. They were then followed from 1999 to 2020, and it was noted whether they developed dementia that required care.
The researchers divided data from a total of 3,739 adults into four groups according to the amount of fiber in their diet. They found that the group that ate the highest levels of fiber had a lower risk of developing dementia.
The team tested whether there were differences for two main types of fiber: soluble and insoluble fiber. Soluble fibers found in foods like oats and legumes are important for beneficial bacteria living in the gut as well as providing 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 more pronounced for soluble fiber.
The team has some ideas about what the link between dietary fiber and dementia risk might be.
“The mechanisms are currently unknown but may involve interactions between the gut and the brain,” Professor 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 is also possible that dietary fiber may reduce other risk factors for dementia such as body weight, blood pressure, lipids and glucose levels. The work is still in its early stages and it is important to confirm connections in other populations.”
In many countries today, such as the United States and Australia, many people consume less fiber than nutritionists recommend. By encouraging healthy eating habits, including those high in dietary fiber, it may be possible to reduce the incidence of dementia.