“We hypothesized that dietary supplementation with bilberry and fish oil would alleviate the signs and symptoms of severe dry eye in both young and older adult age groups compared to age-matched control groups,” the researchers wrote. “To our knowledge, this is the first study to evaluate the qualitative as well as quantitative effects of a combined oral bilberry extract and fish oil supplementation has on severe dry eyes.”
The study, published in the journal Frontiers in Nutrition, was supported by the Hong Kong Jockey Club Charities Trust.
Bilberry and eye health
Native to Europe and a cousin to the North American blueberry, the anthocyanin-rich bilberry (Vaccinium myrtillus L.) is associated with improved blood flow to the eyes, reducing inflammation and protecting the optic nerve and retina from damage.
Clinical studies have shown that the bilberry can help to relieve eye fatigue and improve object focus, contrast sensitivity and tear fluid quality. While limited, research has also explored bilberry’s powerful antioxidant and anti-inflammatory anthocyanin action as remedy for conditions including macular degeneration, glaucoma and cataracts.
For this experiment, the researchers used a bilberry extract combined with a low dose of DHA omega-3, also known for its anti-inflammatory properties in benefit of dry eye relief. Natural health product supplier Squina International Group Ltd. provided the supplements.
Study details
The study recruited 24 young (under 30) and middle-aged (over 48) subjects with severe dry eye symptoms and randomly assigned them to either a test or control group. The test group supplemented with a total of 600 mg bilberry extract (150 mg of anthocyanins) and 240 mg docosahexaenoic acid (DHA)-refined fish oil once daily for three months before breakfast, while the control group received no intervention or placebo.
Mean changes in Ocular Surface Disease Index (OSDI) scores, non-invasive tear break-up time (NITBUT), phenol red thread test (PRT) and percentage of meibomian gland openings were used as outcome measures and assessed at baseline, 1-month and 3-month follow-up.
The study found that OSDI score, NITBUT, PRT and percentage of meibomian gland openings improved after taking the supplements for three months, and that these improvements were consistent between the two age groups.
“The improvement noted in tear stability and tear quantity without any adverse events reported for the duration of the study period shows a promising value in applying bilberry extract to complement currently available dry eye disease treatment,” the researchers concluded.
They suggest that future research explore whether the lower 240 mg dosage of DHA-omega-3 added value or if the anti-inflammatory benefits might be attributed to bilberry alone.
In commenting on the findings, Shaheen Majeed, CEO at BGG Americas, noted that the bilberry anthocyanin dosage of 150 mg per day administered in this study is higher than those reported in previous studies. The natural ingredients supplier markets its own branded bilberry extract (MyrtiPro), backed by four clinical and two cell trials supporting bilberry’s protective effects for eye health.
“Further studies like having both low and high-dose groups might be helpful to determine if there is a dose dependence on its effect,” he added. “Overall, this study adds one more clinical evidence of bilberry extract’s benefits on eye health.”
Source: Frontiers in Nutrition
“Bilberry-containing supplements on severe dry eye disease in young and middle-aged adults: A 3-month pilot analysis”
doi: doi.org/10.3389/fnut.2023.1061818
Authors: Wing Y. Yu