The Link Between Our Gut and Alzheimer’s
Written by Akshaya Karthikeyan
Edited by Theodore Do
Jan 31, 2021
Edited by Theodore Do
Jan 31, 2021
We have all heard the old saying, “Food is Medicine.” In recent years, there have been many speculations about the important role of gut microbiota in disease control. Our gut microbiota influences many aspects of our health. Since our gut microbiota is heavily influenced by the food we eat, this saying may not be far from the truth.
Recent scientific evidence highlights the relationship between gut microbiota conditions and the adaptive immune system. When there is dysbiosis (i.e. imbalance in the gut microbiota), much of the host’s immune responses are exaggerated, causing internal inflammation. Recently, researchers in Shanghai studied the effects of gut microbiota dysbiosis and neuroinflammation in Alzheimer’s disease (AD progression). They noticed a drastic change in the gut microbiota composition in Alzheimer’s patients: an accumulation of two amino acids (phenylalanine and isoleucine) that induces the formation of Th1 immune cells. The interaction of Th1 cells with the microglia of the brain, which is important in immune system activities, results in cognitive impairment as it induces inflammation in the brain, damaging brain matter overtime.
Sodium oligomannate (GV-971), a marine-algae derived compound, has been shown to reduce gut dysbiosis, specifically reducing the inflammation in the brain and is even capable of reversing cognitive impairment. So, how is the gut microbiota involved in this? Our microbiota is made of bacteria that can be both beneficial and harmful. Some harmful bacteria are not of concern when good bacteria are around. This is because when the good bacteria are around, harmful bacteria do not have the space or nutrition to outcompete. When there is dysbiosis, there is often an increase in harmful bacteria that start encroaching our gut mucosal layer (i.e. the mucus lining that protects our intestines), leading to inflammation. So what might cause this imbalance? It really depends on what we eat. When we digest food, the fibers that are not broken down by our digestive juices are metabolized by the microbes in our intestine. Therefore, it is important to consume fiber-rich food that is fuel for many of the ‘good’ bacteria to keep the harmful ones from overgrowing and outcompeting, i.e. to keep them “in balance.” The gut microbiota also produces by-products and releases them in our gut. These by-products are taken up by our body as signals (e.g. to increase body fat). Therefore, the signals that our bodies realize depend on the composition of the gut microbiota and what it ‘eats,’ which depends on what we consume. Similarly, when sodium oligomannate is ingested, the gut microbiota changes in its composition and reduces the output of the two amino acids that contribute to brain damage.
This study is important in understanding the mechanism by which AD progresses in relation to the gut microbiota. Ultimately, this study is critical as it will help create approaches for exploring the intricate relationship between gut microbiota and human ailments. More importantly, it highlights a new perspective on providing holistic and personalized treatments for many of our health problems.
Works Cited
Wang, X., Sun, G., Feng, T. et al. Sodium oligomannate therapeutically remodels gut microbiota and suppresses gut bacterial amino acids-shaped neuroinflammation to inhibit Alzheimer’s disease progression. Cell Res 29, 787–803 (2019). https://doi.org/10.1038/s41422-019-0216-x
“Wild vines of the gut” by Chris Wood, of Oxford Medical Illustration, licensed under CC BY-NC-SA 4.0