Microbiota may determine if pomegranate extracts are beneficial or not

By Stephen Daniells

- Last updated on GMT

© iStock
© iStock

Related tags Nutrition

The potential cardiovascular effects of ellagitannins from pomegranate and walnuts may be either positive or negative depending on their gut microbiota, says a new study.

When we consume ellagitannin-containing foods our microbiota metabolize the compounds differently. Like we see with soy isoflavones and equol, depending on the make-up of your gut microbiota an individual may produce urolithin A, urolithin B, or they may not produce either (non-producers).

New data published in Clinical Nutrition​ indicated that healthy overweight-obese individuals with a urolithin B producing phenotype were at an increased risk of cardiometabolic disease, while urolithin A producers with metabolic syndrome and under statin treatment actually had a lipid profile like that of the healthy non-overweight people. 

“In the new era of ‘personalized nutrition’, stratification of subjects in relation to their UMs [urolithin metabotypes] could supply an additional tool for CVD risk assessment that must be replicated in large cohorts,”​ wrote the researchers.

Study details

The researchers analyzed data from 20 healthy, normal weight people consuming 30 grams per day of walnuts, 49 healthy but overweight-obese individuals ingesting 450 mg per day of a pomegranate extract, and 25 people with metabolic syndrome (MetS) consuming a variety of nuts (15 g-walnuts, 7.5 g-hazelnuts and 7.5 g-almonds/d).

If an individual produced urolithin A, they were classed as urolithin metabotype A (UM-A), if they produced urolithin B they were urolithin metabotype B (UM-B), and if they were non-producers, they were urolithin metabotype 0 (UM-0).

Results showed that cardiometabolic risk factors were observed in the overweight-obese subjects. Urolithin-A was positively and statistically correlated with anti-atherogenic apolipoprotein A-I and intermediate-HDL-cholesterol. On the other hand, urolithin-B and isourolithin-A (characteristic from UM-B) were positively correlated with a range of cardiometabolic risk factors, including total-cholesterol, LDL-cholesterol, apolipoprotein B, VLDL-cholesterol, IDL-cholesterol, and oxidized-LDL.

When the researchers limited their analysis to people with MetS they found that only MetS patients with a UM-A phenotype on statin treatment showed a modification of their lipid profiles to those observed in normal weight people, whereas a poorer response to statins was observed in UM-B phenotype people.

“UMs are potential [cardiometabolic risk] factors biomarkers,”​ wrote the reseachers. “Overweight-obese individuals with UM-B are at increased risk of cardiometabolic disease, whereas urolithin-A production could protect against [cardiometabolic risk] factors.

“[F]urther research is warranted to explore whether the impact of lipid-lowering therapy or dietary interventions with ellagitannin-containing foods such as pomegranate or walnuts on cardiometabolic risk factors differs according to individuals' UMs,” ​they concluded.

Potential anti-aging activity

Researchers from the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland reported last year that urolithin A, a compound generated by gut microflora from ellagitannins, may improve mitochondrial function by stimulating mitophagy, a process by which damaged mitochondria are recycled to permit a renewal with healthy mitochondria.

These potent beneficial effects were observed in C. elegans​, mammalian cells and rodents.

The study’s co-authors founded a start-up company, Amazentis, which has developed a method to deliver finely calibrated doses of urolithin A. Amazentis is presently evaluating urolithin A in a first human clinical trial with results expected in 2017.

Source: Clinical Nutrition
Published online ahead of print, doi: 10.1016/j.clnu.2017.03.012
“The gut microbiota metabolism of pomegranate or walnut ellagitannins yields two urolithin-metabotypes that correlate with cardiometabolic risk biomarkers: Comparison between normoweight, overweight-obesity and metabolic syndrome”
Authors: M.V. Selma, et al. 

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