Study Links Gut Bacteria, Flavonoid-Rich Foods With Lower Blood Pressure

Recent research has linked gut microbiota and cardiovascular disease with reported differences in gut microbial compositions among individuals with and without cardiovascular disease.

Foods with high levels of flavonoids appear to positively impact blood pressure and this association may be partially explained by characteristics of the gut biome, according to a new study published in Hypertension.

Flavonoids are naturally found in many fruits, vegetables, and plant-based foods, such as tea, chocolate, and wine, and have been shown to have many positive health benefits. According to the current study, flavonoids are broken down by the body’s gut microbiome. Furthermore, recent research has linked gut microbiota and cardiovascular disease with reported differences in gut microbial compositions among individuals with and without cardiovascular disease.

“Our gut microbiome plays a key role in metabolizing flavonoids to enhance their cardioprotective effects, and this study provides evidence to suggest these blood-pressure lowering effects are achievable with simple changes to the daily diet,” said lead study investigator Aedin Cassidy, PhD, chair and professor in nutrition and preventive medicine at the Institute for Global Food Security at Queen’s University in Belfast, Northern Ireland.

The researchers examined the association between eating flavonoid-rich foods, blood pressure, and gut microbiome diversity. The team also investigated how variance within the gut microbiome could explain the association between flavonoid-rich food intake and blood pressure.

To investigate this, 904 adults between 25 and 82 years of age were recruited, 57% of whom were men. Investigators evaluated the participants’ food intake, gut microbiome, and blood pressure levels together with other clinical and molecular phenotyping at regular follow-up examinations.

Participants’ intake of flavonoid-rich foods during the previous year was calculated using a self-reported food questionnaire that included questions about the frequency and quantity eaten of 112 foods. The researchers assigned flavonoid values to various foods according to data from the United States Department of Agriculture.

The gut microbiomes of participants were assessed with fecal bacterial DNA and blood pressure levels were assessed 3 times in 3-minute intervals after an initial 5-minute rest period, and after an overnight fast. Lifestyle information was also collected, including sex, age, smoking status, medication use, and physical activity, as well as family history of coronary artery disease, the number of daily calories and fiber consumed, and height and weight.

According to the study, participants who had the highest intake of flavonoid-rich foods had lower systolic blood pressure levels, in addition to greater gut microbiome diversity compared with participants who consumed the lowest levels of flavonoid-rich foods. Up to 15.2% of the association between flavonoid-rich foods and systolic blood pressure was attributable to the diversity found in patients’ gut microbiome.

Furthermore, eating 1.6 servings of berries per day was associated with an average 4.1 mm Hg reduction in systolic blood pressure levels, and approximately 12% of this association was explained by gut microbiome factors. Similarly, drinking 2.8 glasses of red wine per week was associated with an average 3.8 mm Hg lower systolic blood pressure level, 15% of which could be explained by the gut microbiome.

“Our findings indicate future trials should look at participants according to metabolic profile in order to more accurately study the roles of metabolism and the gut microbiome in regulating the effects of flavonoids on blood pressure,” Cassidy said in the press release. “A better understanding of the highly individual variability of flavonoid metabolism could very well explain why some people have greater cardiovascular protection benefits from flavonoid-rich foods than others.”


Gut bacteria and flavonoid-rich foods are linked and improve blood pressure levels. American Heart Association; August 23, 2021. Accessed August 24, 2021.