Flavonoid-rich foods shown to improve blood pressure via gut, reveals American Heart Association

23 Aug 2021 --- Flavonoid-rich foods – such as berries, apples, pears and wine – appear to have a positive effect on blood pressure levels. This association can be explained by the characteristics of the gut, according to new research backed by the American Heart Association.

The study is the first to address the importance of plant foods and the gut microbiome. To further examine its findings, NutritionInsight speaks to lead investigator of the study Dr. Aedín Cassidy, chair and professor in nutrition and preventive medicine at the Institute for Global Food Security at Queen’s University in Belfast, Northern Ireland.

“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,” she explains.

“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.”Flavonoids are broken down by the body’s gut microbiome – the bacteria found in the digestive tract. 

Simple changes to diet
According to Cassidy, what was interesting was that these blood pressure lowering effects were achievable with simple changes to the daily diet.

“Eating around 1.5 servings of berries per day was associated with a 4.1 mm Hg reduction in systolic BP, and gut microbiome factors explained 12 percent of the association,” she continues.

“Drinking approximately three glasses per week of red wine was associated with 3.7 mm Hg lower systolic BP levels, of which 15 percent could be explained by the gut microbiome.”

The flavonoid-gut microbiome interaction associated with blood pressure highlighted in this paper suggests research should focus on inter-individual variability in the gut microbiome in mediating the cardiovascular benefits, Cassidy stresses. 

Spotlight on the gut microbiome
Recent studies found a link between gut microbiota, the microorganisms in the human digestive tract and cardiovascular disease (CVD), which is the leading cause of death worldwide. Gut microbiota is highly variable between individuals, and there are reported differences in gut microbial compositions among people with and without CVD.

With increased research suggesting that flavonoids may reduce heart disease risk, the new study assessed the role of the gut microbiome in this process.

Researchers examined the association between eating flavonoid-rich foods with blood pressure and gut microbiome diversity. The study also investigated how much variance within the gut microbiome could explain the association between intake of flavonoid-rich foods and blood pressure.Flavonoids are compounds found naturally in fruits, vegetables, tea, chocolate and wine, and have been shown in previous research to offer a variety of health benefits to the body.

The analysis of regular flavonoid intake with gut microbiome and blood pressure levels found that study participants who had the highest intake of flavonoid-rich foods, including berries, red wine, apples and pears, had lower systolic blood pressure levels and greater diversity in their gut microbiome than the participants who consumed the lowest levels of flavonoid-rich foods.

Moreover, up to 15.2 percent of the association between flavonoid-rich foods and systolic blood pressure could be explained by the diversity found in participants’ gut microbiome.

“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,” Cassidy continues.

“Our ability to quantify the microbial community has improved dramatically over the last few years which has allowed us to really understand how they interact with what we eat to modify health effects.”

The American Heart Association will be looking to further expand on this research.

“We have recently completed a trial and research worldwide is trying to disentangle the relative importance of the gut microbiome in explaining the relationship between food intake and health,” concludes Cassidy.

By Elizabeth Green