The aim of this study was to determine the effects of dietary supplementation with a combination of
fish oil, bilberry extract, and
lutein on subjective symptoms of
asthenopia in humans by a double- blind, randomized, parallel-group, and placebo-controlled trial. In the Active group, eleven subjects ingested a supplement containing
omega-3 fatty acid-rich
fish oil (
docosahexaenoic acid 783 mg/day,
eicosapentaenoic acid 162 mg/day), bilberry extract (
anthocyanidin 59 mg/day), and
lutein (17.5 mg/day) in soft gel
capsule form, every day for 4 weeks. In the Placebo group, nine subjects ingested placebo capsules. Before and after supplementation, subjects completed a questionnaire to determine their
asthenopia symptoms and were also assessed for
mental fatigue symptom by the visual analog scale (VAS) test.
Asthenopia symptoms such as "stiff shoulder,
low back pain", "frustration", "
dry-eye", and "stuffy head" were improved in the Active group. Furthermore, a score of
mental fatigue was improved after 4 weeks of supplementation, and no side effects were observed after the 4-week supplementation and a 2-week washout period in the Active group. These results suggest that dietary supplementation with the combination of
omega-3 fatty acid-rich
fish oil, bilberry extract, and
lutein may safely improve subjective symptoms of
asthenopia and
mental fatigue in humans.