Total polyphenol intake may determine blood pressure benefit of Mediterranean diet: study

By Tim Cutcliffe contact

- Last updated on GMT

© iStock/ klenova
© iStock/ klenova
Higher intakes of dietary phenolic acids, abundant in the Mediterranean diet, are associated with blood pressure, according to a new study in Nutrients.

The trial, known as the MEAL (Mediterranean healthy Eating, Ageing, and Lifestyle) study, examined  total dietary intake of phenolic acids (also known as polyphenols) in a group of Sicilian adults.  

Individuals with the highest total intakes of dietary phenolic acids (also known as polyphenols), showed a 32% reduction in risk of high blood pressure, no matter which foods they were obtained from, found researchers from the University of Catania, Sicily.

“The findings of this study suggest that dietary phenolic acids may be inversely associated with hypertension, irrespective of their dietary source. Thus, phenolic acid content of the diet may be responsible for the observed beneficial effects on blood pressure of certain foods,” ​wrote first author Justyna Godos.

However, despite the hypertension risk reduction for the highest quartile of phenolic acid intake (median 522 milligrams/ day (mg/d)), there was no statistically significant trend over the four quartiles of intake.

This is consistent with previous research suggesting total intake of polyphenols only showed an inverse relationship with hypertension above a certain threshold. The previous work examined a Brazilian population, where the observed threshold level was 300 mg/d.  

Study details

The cross-sectional study measured dietary polyphenol intake in 2044 adults using food frequency questionnaires (FFQ), which had been previously validated for the Sicilian population. The polyphenol content of foods was calculated using the Phenol-Explorer database.  

The researchers split the study population into quartiles by total phenolic acid intake and correlated them with blood pressure. Adjustments were made for intake of minerals such as sodium, magnesium and other micronutrients that are known to have an effect on blood pressure.

Total intake or specific phenolic acid?

The researchers also looked at whether specific individual phenolic acids and particular food groups had an effect of blood pressure.

The scientists’ sub-analysis looked at hydroxybenzoic, hydoxycinnamic, hydroxyphenylacetic  and caffeic acids.

“When taking into account individual subclasses of phenolic acids, only hydroxyphenylacetic acid was inversely associated with hypertension (highest vs. lowest quartile, OR = 0.63, 95% CI: 0.40, 0.96),” ​reported the team.

The study also identified some gender specific effects. Hydoxycinnamic and hydroxyphenylacetic acids were inversely associated with hypertension in women but not in men, while caffeic acid showed an inverse correlation only in males.

For specific foods, the researchers considered coffee, nuts, tea, olive, red & white wine and beer. Surprisingly, only beer intake was significantly linked with lower hypertension risk.

“Among dietary sources of phenolic acids considered in the analysis, only beer was significantly inversely associated with hypertension (highest vs. lowest quartile, OR = 0.32, 95% CI: 0.15, 0.68),”​ wrote the researchers.

Mechanisms

Phenolic acids are known to improve the health of the endothelium (the cells that line the blood vessels). Previous research has suggested that polyphenols may help dilate blood vessels and/ or act in a similar manner to the blood pressure lowering drugs Angiotensin Converting Enzyme (ACE) inhibitors.

Nevertheless, the researchers called for further work into understanding these mechanisms.

“More in-depth laboratory studies are needed to corroborate the exact mechanisms of action of such foods in order to better understand which compounds improve endothelial health and may affect the risk of hypertension.”

Source: Nutrients

Volume 9, issue 10, published online.  DOI: 10.3390/nu9101069

“Association between Dietary Phenolic Acids and Hypertension in a Mediterranean Cohort”

Authors: Justyna Godoś, Dario Sinatra, Isabella Blanco, Serena Mulè, Melania La Verde and Marina Marranzano

Related news

Related products

show more

How Polyphenols enhance probiotic benefits

How Polyphenols enhance probiotic benefits

BerryPharma® - the Expert in Berry Extracts | 17-Oct-2017 | Research Study

Researchers have recently identified the positive interactions between polyphenols and intestinal bacteria, leading to classification as a prebiotic function....

Related suppliers

comments

Post your comment

We will not publish your email address on the website

These comments have not been moderated. You are encouraged to participate with comments that are relevant to our news stories. You should not post comments that are abusive, threatening, defamatory, misleading or invasive of privacy. For the full terms and conditions for commenting see clause 7 of our Terms and Conditions ‘Participating in Online Communities’. These terms may be updated from time to time, so please read them before posting a comment. Any comment that violates these terms may be removed in its entirety as we do not edit comments. If you wish to complain about a comment please use the "REPORT ABUSE" button or contact the editors.

Follow us

Featured Events

View more

Products

View more

Webinars