Japanese researchers followed more than 3500 men and women ages 40 to 64 for two decades and found that the individuals who ate lots of fiber, especially soluble fiber, had a reduced risk of developing dementia. The researchers suggest that fiber is not only beneficial to our cardiovascular health but also benefits the brain.
According to ScienceDaily, the study was published in in the journal Nutritional Neuroscience.
“Dementia is a devastating disease that usually requires long-term care,” says lead author Dr. Kazumasa Yamagishi. “We were interested in some recent research which suggested that dietary fiber may play a preventative role. We investigated this using data collected from thousands of adults in Japan for a large study that started in the 1980’s.”
The researchers split the participants into four groups depending on the amount of fiber in their diets. They found that the groups who ate higher levels of fiber had a lower risk of developing dementia. They also found that people who ate more soluble fiber found in foods such as oats and legumes rather than insoluble fiber found in whole grains and vegetables, had stronger protection against dementia.
Yamagishi speculates that perhaps soluble fiber in the gut reduces neuroinflammation which plays a role in the onset of dementia, says ScienceDaily. Or, it is possible fiber may reduce other risk factors for dementia, such as body weight, blood pressure, lipids, and glucose levels.
Insoluble fiber passes unabsorbed through the body says Dr. Gabe Mirkin. He adds that a high-fiber diet rich in foods that contain soluble fiber promote the growth of healthy bacteria in the gut that produce short chain fatty acids or SCFAs. These SCFAs help decrease inflammation, which is associated with damage to brain cells and other tissues as part of the aging process.
“Aging is associated with increased loss of brain function, and more than 30% of adults in North America over the age of 65 suffer from dementia,” Mirkin explains. “This loss of brain function may be linked to the way aging changes the composition of bacteria in your colon. As humans age, the number of different colon bacteria markedly and progressively decreases. The loss of bacterial variety is associated with increased risk for brain damage, such as loss of memory, Alzheimer’s disease, and Parkinson’s disease.”
Mirkin adds that the low-fiber typical Western diet significantly reduces the number of different types of bacteria in your colon, but a change in diet can rapidly increase the diversity and number of healthful colon bacteria at any age, even if a low-fiber diet has been followed for a long time.
“Your current diet determines which bacteria live in your gut,” says Mirkin. Even if your colon is full of harmful bacteria, you can change your colon bacteria by switching to a high-fiber diet that includes a wide variety of vegetables, whole grains, beans, nuts, and other seeds. A healthful diet, together with weight control, a regular exercise program and avoiding alcohol and smoking, will help protect your brain from dementia and the many other diseases that are linked to the typical Western diet and lifestyle.”