In the news: Flavonoids, Especially Anthocyanins, May Improve Blood Pressure

Dietary Flavonoids Linked to Improved Blood Pressure, Partially via Gut Bacteria

Strong epidemiological evidence ties intake of the anthocyanin flavonoids with a reduced risk for cardiovascular disease and coronary heart disease. However, its effects on blood pressure in human studies has been less consistent.

A newly published study(1) evaluated the relationship between consuming flavonoid-rich foods and blood pressure. and examined the association between the consumption of those foods and gut bacteria diversity.

The results suggest that flavonoids have a positive effect on blood pressure, and that this association is at least partially explained by characteristics of the gut microbiome.

Design and Methods

Researchers from Queen’s University Belfast analyzed data from over 900 men and women from Germany’s PopGen biobank in this population-based study. Participants’ intake of flavonoid-rich food was evaluated over time using food frequency question-naires.

Systolic and diastolic blood pressure (BP) was consistently measured 3 times at 3-minute intervals after an initial 5-minute rest period. Gut microbiome composition was sequenced from 16S ribosomal RNA genes.

Results

The highest intake of flavonoid-rich foods (specifically the polymer subclass) was associated with lower systolic BP (P=0.01). These foods included berries, red wine, pears, and apples. Participants in the highest intake bracket vs. the lowest also had greater gut microbiome diversity.

The data suggest that up to 15.2% of the link between flavonoid-rich foods and systolic BP could be explained by the gut microbiome, which plays a key role in metabolizing flavonoids to bioactive and bioavailable compounds.

Specifically, higher berry intake (1.6 servings daily with a serving = 1 cup, and containing an estimated 112 mg of anthocyanins) was associated with 4.1 mm Hg lower systolic BP. About 12% of this association could be explained by higher alpha and beta diversity and lower relative abundance of Parabacteroides. Alpha diversity is the diversity in a single sample site, while beta diversity is the difference in diversity in different regions of the gut.

For red wine, intake of 2.8 glasses (250 mL) per week was associated with 3.7 mm Hg lower systolic BP of which 15.2% could be explained by a combination of alpha diversity and higher relative abundance of unclassified Ruminococcaceae.

There were no associations with diastolic BP.

Comments

According to the researchers, the magnitude of the association between anthocyanin intake and systolic BP (−4.8 mm Hg) is similar to their previous study in a female cohort(2).

“A reduction in systolic BP of this scale is likely to have clinical benefits with previous studies showing that 5 mm Hg reduction in systolic BP reduces stroke risk by 13% over 295 652 patient-years”, the authors explain. Anthocyanins have previously been shown to have anti-inflammatory, antioxidant, and lipid-lowering effects.

References

1. Jenkins A, et al. Microbial diversity and abundance of Parabacteroides mediate the associations between higher Intake of flavonoid-rich foods and lower blood pressure. Hypertension. 78:1016–26, 2021
2. Jennings A, et al. Higher anthocyanin intake is associated with lower arterial stiffness and central blood pressure in women. Am J Clin Nutr. 296:781–788, 2012.