Benefits
Eye focusing after screen work (other bilberry extracts and a BGG blend)
In BGG's 6-week trial of about 120 mg a day of the extract alone in 32 adults, pupil response did not differ from placebo across participants; a BGG blend with astaxanthin and lutein improved it. In trials funded by other makers, 240 mg a day of their bilberry extract for 12 weeks improved a focusing muscle measure, and 480 mg a day for 8 weeks lessened a drop in flicker fusion after screen work.
Blood pressure, blood lipids and antioxidant status (another extract)
The MyrtiPRO trials cited here did not measure these, or retinal blood flow. In a 4-week randomized, placebo-controlled crossover trial of a different bilberry extract, 20 adults with type 2 diabetes took 1.4 g a day, and body weight, blood pressure, blood lipids, antioxidant status, oxidative stress and inflammation markers did not differ from placebo.
Night vision in placebo-controlled trials
A review of 12 placebo-controlled trials found the four most recent randomized trials of bilberry for night vision all negative and concluded that rigorous studies do not support better normal night vision. In one of them, 15 young men with good vision took 480 mg a day of a 25% extract for 3 weeks with no change in night visual acuity or contrast sensitivity. MyrtiPRO has not been tested for night vision.
Tear film and tear volume measures
In BGG's 6-week trial of the extract alone, tear film break-up time and the Schirmer tear test did not differ from placebo, and a dry eye feeling after screen work was rated higher with bilberry. Mirtoselect, a different bilberry extract made by Indena, increased tear volume more than placebo in the right eye only in a 4-week trial of 21 adults.
Anthocyanin content and identity of bilberry products
Bilberry extracts are often adulterated. One analysis found about half of 14 commercial extracts differed from authentic bilberry and about 60% held less anthocyanin than declared, mostly from mulberry or chokeberry; another rated 45% of bilberry supplements unacceptable; and one extract passed the usual UV assay while carrying a synthetic red dye that only HPLC detected. BGG specifies MyrtiPRO by HPLC, which describes content, not effects.
Mechanism of action
Retinal Microcirculation
Proposed but not demonstrated. None of the MyrtiPRO trials cited here measured retinal or eye blood flow.
Antioxidant Activity
Bilberry fruit contains 15 identified anthocyanins, and that profile is what identity testing checks against. Anthocyanins are described as antioxidants, but blood measures of antioxidant status did not differ from placebo in a randomized trial of another bilberry extract in people.
Identity testing of bilberry extracts
BGG's leaflet states an HPLC anthocyanin specification and HPLC profile for MyrtiPRO. Reported bilberry adulterants are not limited to related species: they include mulberry and chokeberry extracts, other Vaccinium species, elderberry, and at least one case of a synthetic azo dye, amaranth, which passed the standard UV anthocyanin assay and was caught only by HPLC.
Clinical trials
Randomized, double-blind, placebo-controlled, parallel-group, 6 weeks; funded by BGG Japan and Arysta Health and Nutrition Sciences, which together with Beijing Gingko-Group employ five of the six authors; the paper does not name the product and BGG's leaflet lists it as a MyrtiPRO study; secondary outcomes were tear film break-up time, Schirmer test, shoulder muscle hardness and symptoms, with a dry eye sensation score and muscle hardness higher on bilberry; journal not PubMed-indexed (Sekikawa et al. 2021, Functional Foods in Health and Disease)
32 healthy Japanese adults with eye fatigue after screen use were randomized and 15 per group were analyzed; one capsule a day supplying 43.2 mg of anthocyanins (120 mg of BGG Japan bilberry extract powder) or placebo
Across participants, the primary pupil response measure did not differ from placebo. When each eye was analyzed separately, the change in pupil response across a screen session (p = 0.043) and pupil response per near point (p = 0.049) were better with bilberry. No adverse events were reported.
Randomized, double-blind, placebo-controlled, 6 weeks; sponsored by BGG Japan and DHC Corporation, which employ five of the six authors; BGG's leaflet lists it as a MyrtiPRO study; a blend, so no result can be assigned to bilberry; tear break-up time, Schirmer test, macular pigment and muscle hardness did not differ from placebo (Kizawa et al. 2021, Journal of Clinical Biochemistry and Nutrition)
44 Japanese adults with eye fatigue after screen use, 20 per group analyzed; two capsules a day supplying 200 mg of BGG Japan bilberry extract (72 mg of anthocyanins), 6 mg of astaxanthin and 10 mg of lutein, or placebo
At 6 weeks the change in pupil response across a screen session (average of both eyes) was better than placebo (p = 0.036), as were scores for trouble focusing and for seeing nearby objects or fine print.