, an association that is partially explained by bacteria in an individual’s gut microbiome, new research suggests.
In a population-based study of more than 900 individuals, those with the highest intake of flavonoid-containing foods had significantly lower systolic blood pressure and pulse pressure, as well as greater gut microbial diversity, compared with those with the lowest intakes.
Up to 15% of this observed association was explained by the gut microbiome, suggesting that these microbes play a key role in metabolizing flavonoids to enhance their cardioprotective effects, according to the researchers.
The study was published online in the journal Hypertension.
“We know what we eat plays a critical role in shaping our gut microbiome, but little is known about the relative importance of plant foods and specific constituents called flavonoids,” lead researcher Aedin Cassidy, PhD, chair and professor of nutrition and medicine at the Institute for Global Food Security, Queen’s University, Belfast, Northern Ireland, said in an interview.
“Unlike many other food constituents, flavonoids are predominantly metabolized in the gut, suggesting that the gut microbiome may be more important in enhancing their biological activity than for other things we eat,” Dr. Cassidy said.
“There is mounting evidence from population-based studies and clinical trials that a higher intake of flavonoids and flavonoid-rich foods can improve heart health, but for the first time, we provide data highlighting the key role of the gut microbiome in explaining the association between such foods and blood pressure,” she noted. “This is one of the first studies to address this.”
For this analysis, Dr. Cassidy and her group sought to assess to what extent the composition of the gut microbiome might explain the association of habitual flavonoid and flavonoid-rich food intake with systolic and diastolic blood pressure in a community-based sample of 904 individuals aged 25-82 years from Germany’s PopGen biobank.
The researchers evaluated 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 from a self-reported food questionnaire detailing the frequency and quantity eaten of 112 foods, and flavonoid values were assigned to foods according to United States Department of Agriculture data on flavonoid content in food.
Participants’ gut microbiome was assessed by fecal bacterial DNA extracted from stool samples.
After an overnight fast, participants’ blood pressure levels were measured three times in 3-minute intervals after an initial 5-minute rest period. Researchers also collected participants’ diet and lifestyle information.
Analysis of the data showed the following:
- Eating 1.5 servings of berries per day (about 1 cup) was associated with a 4.1–mm Hg reduction in systolic BP; 12% of this association was explained by gut microbiome factors.
- Drinking three glasses of red wine per week was associated with a 3.7–mm Hg reduction in systolic BP; 15% of this association was explained by the gut microbiome.