Dry eye disease (DED) affects the surface of the eye, creating discomfort, inflammation, visual disturbance. It can also potentially damage the eye. According to previous research, DED is becoming much more prevalent, partly due to the increasing number of hours spent on computers, tablets and smartphones. The recent trend towards smaller screens also intensifies eyestrain, an underlying factor in DED.
The research, published in the European Review for Medical and Pharmacological Sciences, used Indena's newly developed formulation of bilberry extract - finding that it appears to relieve DED symptoms.
“The findings of our study indicated that natural, standardised bilberry extract (Mirtoselect) may improve tear secretion and enhance antioxidant potential,“ wrote Antonella Riva, product research manager at Indena SpA, manufacturers of Mirtoselect who conducted the study.
Increasing tear production brings symptom relief to DED sufferers. This may be of particular benefit to people with more severe symptoms, whose quality of life and work productivity can be affected by DED.
“A subset analysis revealed that Mirtoselect could be more effective in subjects with higher tendency of dry eye,” commented Riva.
Study results also show that Mirtoselect may improve participants’ balance of anti-oxidant potential versus oxidant stress. Previous research suggests this ratio may increase protection against reactive oxygen metabolites.
Bioavailability
The researchers formulated Mirtoselect to include compounds present in bilberry fruit, in order to promote bioavailability of the active anthocyanin compounds.
Their theory was that higher anthocyanin content in itself was not the driving factor in determining bioavailability.
To test this, they carried out a parallel study in rats. This compared the effect of oral administration of natural bilberry extract with a standardised 36% anthocyanin content (Mirtoselect) with an enriched extract containing 89% anthocyanins, but lacking other non-anthocyanin compounds occurring in bilberry fruit.
Rats fed with Mirtoselect showed significantly greater increases in blood levels of anthocyanins than those given the enriched anthocyanin content formulation (EACF).
The researchers noted that “anthocyanins are four times more available when orally administrated in rat as natural bilberry extract (Mirtoselect) than as an enriched fraction.”
The EACF was used as the placebo product in the human study, a small double-blinded randomised controlled trial (RCT).
Non-anthocyanins important
Findings from both animal and human studies support the researchers’ claim that anthocyanin bioavailability depends on the interaction with non-anthocyanin compounds naturally present in bilberry fruit. These include vitamins, sugars, tannins and pectins.
“Our results suggested that natural, standardized bilberry extract (Mirtoselect®) is a natural more bioavailable delivery form anthocyanins, suggesting a strong matrix effect exerted by the non-anthocyanin component,” the team concluded.
They also suggested that next steps should include in-depth investigation of the mechanism of action of bilberry extract in larger studies, and developing a full pharmokinetic profile of the compound.
Source: European Review for Medical and Pharmacological Sciences
Volume 21, Issue 10, Pages 2518-2525,
“The effect of a natural, standardized bilberry extract (Mirtoselect®) in dry eye: a randomized, double blinded, placebo-controlled trial”
Authors: Antonella Riva et al