Looking to get your blood pressure under control? New research from the American Heart Association reveals flavonoid-rich foods such as berries, wine, apples and pears have a positive effect on blood pressure levels. Study authors believe these findings have at least some connection to the influence of the gut microbiome.

“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 investigator Aedín Cassidy, Ph.D., from the Institute for Global Food Security at Queen’s University Belfast in a media release.

So what exactly are flavonoids?

These compounds occur naturally in many fruits, vegetables and other plant-based foods, including tea, chocolate and wine. Earlier studies have shown flavonoids are very beneficial from a health perspective. Flavonoids break down in our stomachs with help from the gut microbiome, or the healthy bacteria residing within each person’s digestive tract. Recent research has established a connection between gut microbiota and a person’s risk of cardiovascular disease. For instance, each person’s microbiota is a bit different and people with cardiovascular disease usually show distinct gut microbial compositions in comparison to those who do not.

In light of more research emerging in recent years suggesting flavonoids may help reduce heart disease risk, this study’s authors set out to determine the role the gut plays in all of this. More specifically, researchers investigated the association between eating flavonoid-rich foods in connection to blood pressure and gut microbiome diversity.

To do this, researchers recruited 904 adults between 25 and 82-years-old. Each person’s food intake, gut microbiome and blood pressure levels were all examined and measured, in addition to other clinical and molecular phenotyping that took place at regular follow-up examinations.

The team used food questionnaires to gather information on each person’s flavonoid-rich food consumption over the years for 112 different foods. Meanwhile, they assessed the group’s gut microbiome by collecting fecal bacterial DNA from stool samples. After an overnight fast, researchers measured each person’s blood pressure on three occasions in three-minute intervals. Scientists also factored in various lifestyles aspects, including sex, age, smoking status, medication use and physical activity. The results also adjusted for family heart disease history, daily calories and fiber consumed, height and weight.

More wine is good for the heart?

Results reveal people with the highest intake of flavonoid-rich foods also had both lower systolic blood pressure levels and greater gut microbiome diversity than those who consumed very little flavonoid-rich foods. Additionally, study authors conclude up to 15.2% of the link between flavonoid-rich foods and blood pressure could be explained by gut microbiome diversity.

Moreover, the study estimates eating 1.6 servings of berries daily (one serving equals 80 grams) results in an average drop in blood pressure of 4.1 mm/Hg. Researchers say roughly 12% of that association has to do with the gut microbiome. Also, drinking 2.8 glasses of red wine weekly (125 ml of wine per glass) can lower blood pressure by an average of 3.7 mm/Hg. The gut microbiome accounts for about 15% of this benefit.

“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. “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.”

The research team notes, however, these findings shouldn’t be used as an excuse to drink more alcohol. For those deciding to drink a bit more wine, researchers suggest you consult your doctor first. The American Heart Association adds while alcohol can be one component of a healthy diet, moderation is essential. It’s recommended that men only drink no more than two alcoholic beverages per day and women limit themselves to one.

The study is published in Hypertension.