Stroke is a disease that affects the cerebral arteries that supply blood to the brain . It occurs when the blood and oxygen supply to the brain gets disrupted. This can happen due to a blood clot (ischemic stroke) or when the blood vessels rupture (hemorrhagic stroke) . According to the U.S. Centers for Disease Control and Prevention (CDC), more than 795,000 people in the U.S. suffer from stroke every year .
Recent studies have suggested the importance of our gut health and microbiota in lowering the risk of stroke. World Stroke Day is held on 29 October every year to help raise awareness about this public health emergency . Read on to learn more about how gut health and microbiota may affect stroke and post-stroke management, as well as how they can potentially be new modifiable risk factors for stroke.
Optimum gut health means having the right balance of good gut microbes and bad ones in our gut. This composition of microorganisms in our gut is collectively termed gut microbiota. Our gut consists of trillions of such microorganisms, including bacteria, viruses, fungi and protozoa species. This set of gut microbiota is unique to everyone at birth and changes during the course of your life due to several factors including environmental, lifestyle, dietary habits, and consumption of medications such as antibiotics.
The innate set of gut microbiota (the set that we are born with) is thought to be the most optimum for oneself. This optimum composition deteriorates as we age. Along with poorer modern-day diets lacking in prebiotics (i.e., food for the beneficial gut bacteria) as well as increased use of medications, the composition and amount of good gut bacteria decrease even faster.
Dysbiosis refers to an alteration of the gut microbiota. Poor gut health and dysbiosis have been found to negatively affect risk factors for stroke such as blood pressure , sugar  and cholesterol  levels. This can potentially lead to an increased risk of stroke.
Apart from mitigating risk factors for stroke, our gut health and microbiota may be directly related to stroke.
Dysbiosis is not only associated with poorer control of metabolic markers like blood pressure, sugar and cholesterol. Such alterations in gut microbiota compositions have also been found in patients with stroke as compared to healthy patients. A study presented at the European Stroke Organisation Conference (ESOC 2022) identified certain types of bacteria such as Negativibacillus and Lentisphaeria that were associated with a more severe stroke in the acute phase .
Beneficial gut bacterial species feed on prebiotics in a fermentation process. This process produces metabolites such as short-chain fatty acids (SCFAs). SCFAs can regulate inflammation, blood pressure and sugar, which are all important risk factors for stroke. These metabolites have also been found to be in lower levels in patients with ischemic stroke as compared to healthy individuals .
Our gut health and microbiota also play important roles during post-stroke recovery by modulating several key parameters:
There is accumulating research showing the importance of gut health and microbiota in affecting the risk of stroke. Dysbiosis is associated with stroke and several risk factors of stroke such as blood pressure, sugar and cholesterol levels as well. The use of prebiotics to induce positive changes to our gut microbiota and improve our gut health is one option we can consider to reduce the risk factors for stroke.
This article is written in conjunction with World Stroke Day, which falls on 29 Oct every year.