EFSA halts grape extract claim said to benefit blood pressure
The Panel’s conclusions concerning the grape seed extract MegaNatural-BP, produced by US firm Polyphenolics, describes the submitted evidence as ‘insufficient to establish a cause and effect relationship between its consumption and maintenance of normal blood pressure.’
“The Panel also took into account that the evidence provided did not establish a plausible mechanism by which the food could exert the claimed effect in vivo in humans,” the Authority adds.
MegaNatural-BP is made of grapes containing total phenolics (90–93%), gallic acid (greater than or equal to 2%) and catechin and epicatechin (greater than or equal to 5%).
The distribution of phenolic compounds in the product is on average 9% monomers, 69% oligomers and 22% polymers.
The application published in the EFSA journal states the target population for the intended health claim is healthy adults with a quantity of 300 milligrams per day (mg/day) recommended.
International distributor
According to the applicant, Polyphenolics’ international distributor, Praline i Čokolada j.d.o.o, MegaNatural-BP’s main health effect relates to the ‘maintenance of normal blood pressure through endothelium dependent vasodilatation.'
"The outcome variables used to establish the claimed effect include multiple ambulatory measurements of systolic and diastolic blood pressure and elevation of oxidised LDL in serum," the Croatian firm adds.
Central to the application was the proposed mechanism of action, which stated the extract was able to cause endothelium-dependent relaxation of the blood vessels through antioxidant activity and inhibit endothelin-1 (ET-1) synthesis.
ET-1 is better known as a potent vasoconstrictor and acts as the natural counterpart of the vasodilator nitric oxide (NO). ET-1 contributes to vascular tone and regulates cell production.
In vivo studies in humans that were included in the application includes one that measured the effect of MegaNatural-BP at 300 mg/day for 6 weeks in subjects with high normal BP.
Despite the reported effect of MegaNatural-BP on daytime Systolic Blood Pressure (SBP), no effect of MegaNatural-BP was found on endothelium-dependent flow-mediated dilation (FMD) compared to placebo.
The Panel notes that this study provides no evidence for a mechanism by which MegaNatural-BP could exert an effect on BP.
Ingredient efficacy
It was a similar finding for another study submitted as evidence. Researchers investigated the effect of MegaNatural Gold on the total antioxidant capacity of plasma and lipoprotein oxidation as compared to red wine, grape juice and tocopherols.
The Panel notes that MegaNatural Gold is not the food that is the subject of the claim and considers that it is unclear how a change in the variables assessed could affect BP in humans.
The application’s In vitro studies were also an issue of contention with one study adding MegaNatural-BP to rabbit aortic rings that were pre-contacted with noradrenaline.
The extract triggered a dose-dependent relaxation with the magnitude of the effect similar to the effect exerted by acetylcholine given in the same concentrations. After the removal of endothelium, the relaxation effect disappeared.
Despite the outcome, the Panel dismissed the evidence on the grounds that there was no information on how the concentration used in these in vitro studies relates to the concentration of MegaNatural-BP in human serum.
“The profile of the active component(s) is undefined,” EFSA says. “It is not clear whether there are changes from metabolism by, e.g. the liver.
“The Panel considers that the results of these in vitro studies do not provide sufficient evidence for a mechanism by which MegaNatural-BP could exert an effect on BP in vivo in humans.”
