While stroke is a leading cause of death and disability in the U.S., African Americans have long experienced higher stroke rates. Researchers are investigating potential new risk factors such as variations in blood levels of metabolites -- substances in the blood produced while exercising or during metabolism. One such metabolite, called gluconic acid, serves as a lifestyle-related biomarker directly linked to diet and exercise.

The study analyzed health data for more than 2,000 people participating in the Reasons for Geographic and Racial Difference in Stroke (REGARDS) study. The ongoing study has enrolled more than 30,000 Black and white adults across the country since 2003. The new analysis included 1,075 adult ischemic stroke survivors during a mean follow-up period of seven years. Of the included participants, 439 were Black and 636 white (mean age 70 years; 50% female). A random comparison group of study participants consisted of nearly 1,000 Black and white adults who had not had a stroke (mean age 65 years; 55% female).

Blood samples were collected from REGARDS participants from 2003 to 2007. The researchers extracted and measured levels of 162 metabolites in the participants' blood. Data analysis examined the association between these metabolite levels and high blood pressure and future ischemic stroke risk in both Black and white adults.

Of the 162 metabolites measured, elevated levels of the metabolite gluconic acid were found in Black adults with high blood pressure, but not their white peers with high blood pressure. Black adults with the highest gluconic acid levels were 86% more likely to have high blood pressure. Black adults with the highest gluconic acid levels also had a 53% increased risk of ischemic stroke. Similar associations were not found among white participants.

After adjusting for multiple factors, a higher level of gluconic acid was associated with foods high in added fats, fried foods, processed meats, and sugary drinks, a lower level of education, and a lack of exercise. The researchers say that blood tests measuring metabolites like gluconic acid may help point individuals toward more targeted guidance for stroke prevention, and determine if diet and exercise are working to lower stroke risk.

"Gluconic acid may be considered as a dietary-related oxidative stress marker due to its availability in food, potentially produced by the gut microbiome, and related to diseases with oxidative stress," said Massachusetts General Hospital neurologist and lead author Dr. Naruchorn Kijpaisalratana, PhD, in a statement. "We think that this biomarker may provide a pathway to improve diet and exercise habits to help prevent a future stroke."