Scientists from the National Center for Geriatrics and Gerontology and other institutions have found that eating a Japanese-style diet may be associated with a reduced risk of cognitive decline.
Cognitive decline can range from mild cognitive impairment to dementia, a condition marked by a severe loss of cognitive abilities that interferes with daily life. Alzheimer’s disease is the most common form of dementia.
Previous studies have suggested links between gut health and cognitive decline. However, the role of overall dietary patterns in these associations has remained unclear.
In the current study, researchers aimed to examine the relationships between adherence to a Japanese-style diet, the gut microbiota, and cognitive decline.
A traditional Japanese diet is rich in steamed rice, noodles, fish, tofu, natto, seaweed, and fresh, cooked, or pickled fruits and vegetables, while being low in added sugars and fats. It may also include small amounts of eggs, dairy products, or meat, though these typically make up a minor part of the diet.
The researchers also sought to compare three versions of the Japanese Diet Index to determine which showed the strongest associations with cognitive function and gut microbiota profiles.
Using data from a hospital-based study, the team assessed the dietary intake, risk factors, cognitive function, brain imaging results, and gut health of 85 older patients.
They found that, compared with participants diagnosed with dementia, those without dementia were more likely to consume healthier foods, including fish and shellfish, mushrooms, soybeans and soybean-derived products, and coffee.
The study also observed trends toward lower levels of certain gut microbial metabolites among participants who adhered more closely to a traditional Japanese diet.
In addition, participants with dementia had lower scores on the traditional Japanese Diet Index than those without dementia.
Based on these findings, the researchers suggest that adherence to a traditional Japanese-style diet is associated with a lower risk of cognitive decline and may also be linked to reduced levels of gut microbial metabolites.
The study was conducted by Naoki Saji and colleagues and published in the journal Nutrition.
