Gut bacteria and flavonoid-rich foods are linked and improve blood
pressure levels

Date:
August 23, 2021
Source:
American Heart Association
Summary:
Flavonoids found in plants and plant foods such as berries, apples,
tea, wine and dark chocolate are known to offer health benefits,
including some protective effects on the cardiovascular system. A
study of over 900 adults in Germany evaluated the quantity and
frequency of eating flavonoid-rich foods and measured bacteria in
the gut microbiome to determine if there was an association with
blood pressure levels.



FULL STORY ========================================================================== Flavonoid-rich foods, including berries, apples, pears and wine, appear
to have a positive effect on blood pressure levels, an association
that is partially explained by characteristics of the gut microbiome,
according to new research published today in Hypertension, an American
Heart Association journal.


==========================================================================
"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 of the study
Aedi'n Cassidy, Ph.D., chair and professor in nutrition and preventive
medicine at the Institute for Global Food Security at Queen's University
in Belfast, Northern Ireland.

Flavonoids are compounds found naturally in fruits, vegetables and
plant-based foods such as tea, chocolate and wine, and have been
shown in previous research to offer a variety of health benefits to
the body. Flavonoids are broken down by the body's gut microbiome --
the bacteria found in the digestive tract.

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 flavonoids may reduce heart
disease risk, this study assessed the role of the gut microbiome
on the 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.

A group of 904 adults between the ages of 25 and 82, 57% men from
Germany's PopGen biobank were recruited for this study. (The PopGen
biobank includes participants from a network of seven biobanks in
Northern Germany.) Researchers evaluated the 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. Flavonoid values were assigned to foods according to United States Department of Agriculture data on flavonoid
content in food.

Gut microbiome for participants was assessed by fecal bacterial DNA
extracted from stool samples. After an overnight fast, participants'
blood pressure levels were measured three times in three-minute intervals
after an initial five-minute rest period. Researchers also collected participants' lifestyle information, including sex, age, smoking status, medication use and physical activity, as well as family history of
coronary artery disease, the number of daily calories and fiber consumed,
and each participant's height and weight was measured to calculate BMI
(body mass index).

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

* Up to 15.2% of the association between flavonoid-rich foods and
systolic
blood pressure could be explained by the diversity found in
participants' gut microbiome.

* Eating 1.6 servings of berries per day (one serving equals 80 grams,
or 1
cup) was associated with an average reduction in systolic blood
pressure levels of 4.1 mm Hg, and about 12% of the association
was explained by gut microbiome factors.

* Drinking 2.8 glasses (125 ml of wine per glass) of red wine a
week was
associated with an average of 3.7 mm Hg lower systolic blood
pressure level, of which 15% could be explained by the gut
microbiome.

"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," said Cassidy. "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." While this study suggests potential benefits to consuming red wine, the American Heart Association suggests
that if you don't drink alcohol already, you shouldn't start. If you do
drink, talk with your doctor about the benefits and risks of consuming
alcohol in moderation. According to a statement on dietary health by the American Heart Association, alcohol intake can be a component of a healthy
diet if consumed in moderation (no more than one alcoholic drink per day
for women and 2 alcohol drinks per day for men) and only by nonpregnant
women and adults when there is no risk to existing health conditions, medication-alcohol interaction, or personal safety and work situations.

The authors note that participants for the study were from the general population, and the participants were unaware of the hypothesis. However, residual or unmeasured confounding factors (such as other health
conditions or genetics) can lead to bias, thus these findings cannot prove
a direct cause and effect, although the researchers did conduct a detailed adjustment in their analyses for a wide range of diet and lifestyle
factors. The authors noted the focus of this study was on specific foods
rich in flavonoids, not all food and beverages with flavonoids.

========================================================================== Story Source: Materials provided by American_Heart_Association. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Amy Jennings, Manja Koch, Corinna Bang, Andre Franke, Wolfgang Lieb,
Aedi'n Cassidy. Microbial Diversity and Abundance of Parabacteroides
Mediate the Associations Between Higher Intake of Flavonoid-Rich
Foods and Lower Blood Pressure. Hypertension, 2021; DOI: 10.1161/
HYPERTENSIONAHA.121.17441 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/08/210823085617.htm

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