Flavonoid-rich food associated with lower blood pressure and microbiome diversity, says recent study

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A recent study published in Hypertension¹ found that a diet high in flavonoid may help reduce blood pressure. In the study, more than 900 subjects have their systolic and diastolic blood pressure measured, and had their diet assessed using a self-administered 112-item food frequency questionnaire. Flavonoid content values were assigned to each of the foods on the questionnaire’s list. Intakes were derived for the main subclasses of flavonoids habitually consumed: flavanones, anthocyanins, flavan-3-ols, flavonols, flavones, polymers, and proanthocyanidins separately. Total flavonoid intakes were calculated by summing the 6 component subclasses (flavanones, anthocyanins, flavan-3-ols, flavonols, flavones, and polymers). Researchers also analyzed the gut microbiome of subjects.

Results showed that higher intakes of total flavonoids, anthocyanins, polymers, and the proanthocycanidin component of the polymer class were associated with statistically significant lower systolic blood pressure and pulse pressure. Higher intakes of flavan-3-ols were associated with lower systolic blood pressure, and higher intakes of flavonols and flavones were associated with lower pulse pressure. The foods associated with significantly lower systolic blood pressure and pulse pressure were berries and red wine. Higher intakes of apples, pears, and peppers were associated with lower pulse pressure. For example, eating 80 grams of berries per day was associated with an average reduction in systolic blood pressure levels of 4.1 mm Hg, and drinking 250 ml of red wine per week (just under three glasses) was associated with 3.7 mm Hg lower systolic blood pressure levels.

Flavonoid intakes were also associated with different microbiome composition. For example, higher intakes of berries and red wine were associated with higher microbial alpha diversity and lower relative abundance of the Parabacteroides genus. Higher intakes of red wine was also associated with higher abundance of Oscillibacter, and unclassified Ruminococcaceae. Higher abundance of Parabacteroides was associated with significantly higher systolic blood pressure while higher abundance of unclassified Ruminococcaceae was associated with lower systolic blood pressure and pulse pressure. And a higher alpha diversity was associated with lower systolic blood pressure. Up to 15.2% of the association between flavonoid-rich foods and systolic blood pressure can be explained by microbiome diversity, says the study.

“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 the study’s lead researcher, Professor Aedín Cassidy from the Institute for Global Food Security (IGFS) at Queen's University Belfast. “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. 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.”

Reference

1. Jennings A et al. “Between higher intake of flavonoid-rich foods and lower blood pressure.” Hypertension, vol. 78 (2021): 1016-1026