Revised by Dr. Shien Tseng
The human gut is home to a diverse community of microorganisms collectively known as the gut microbiome. Numerous clinical studies have revealed associations between the gut microbiome and dementia-- for example, a cross-sectional study conducted in Japan found a significant difference between the gut microbiomes of individuals with dementia and those without the disease. Those with dementia exhibited a lower number of Bacteroides, a species known to reduce inflammation, and a higher prevalence of microbes associated with dementia; this is supported by two other studies that explored gut microbiome metabolites.
It is widely acknowledged that diet plays a pivotal role in shaping the composition of the gut microbiome. The Mediterranean diet, known for its health benefits, have shown positive effects in reducing dementia risk and progression. These diets emphasize a rich variety of plant-based foods, and it is this diversity that could be a key factor in their success. Research suggests that a diet low in fiber and plant diversity leads to reduced microbiome diversity and an increase in inflammatory species. This reduced microbiome diversity is associated with poor diet quality, particularly when faced with major life changes. However, it is essential to consider the possibility of reverse causality, where individuals in the early stages of cognitive decline may reduce the quality of their diet, accelerating the dementia process.
The link between a varied diet, the gut microbiome, and dementia might be attributed to the role of gut microbes in reducing inflammation. Evidence suggests that a diverse gut microbiome helps suppress inflammation, which is a known factor in dementia development. Although randomized control trials are needed to establish a direct cause-and-effect relationship, it is helpful to adopt a diet that reduces the risk of heart disease and supports the microbiome. Maintaining regular exercise alongside a balanced diet further complements these efforts.
As our understanding of dementia and its risk factors continues to evolve, evidence is mounting that suggests a link between the gut microbiome and the development of
dementia. A rich and varied diet appears to support a diverse gut microbiome, which in turn may help in the prevention of the onset of dementia. While there is still much to learn, the best approach at this juncture seems to be adopting a heart-healthy diet, regular exercise, and intellectual engagement. In the ongoing quest to reduce the risk of cognitive decline, it is evident that lifestyle factors play a significant role, and making good dietary choices can be very crucial.