Sunrouge tea extract may improve visual function
Long-term consumption of the green tea cultivar Sunrouge led to significant improvement in accommodation ability (AA, ie, focusing ability of the eye) and eyestrain among healthy adults under 45 years and those who operated visual display terminals (VDTs, ie, computers, smartphones, or tablets) daily, according to a Japanese study.
A total of 120 healthy individuals (aged 21–55 years, 58 percent female) were randomized 1:1:1 to receive green tea with either Sunrouge or Yabukita extract, or a placebo infusion of barley extract without catechins and caffeine, for 12 weeks. AA was monitored twice (after stress and break periods) while eyestrain symptoms were evaluated before and after tea intake. Evaluation was stratified for age comprising non-presbyopic participants under 45 years as accurate AA measurements could not be obtained among presbyopic individuals, as well as for daily VDT use. Observations were limited to the left eye considering eye dominance. [Nutrients 2018;10:569]
After stratifying for age, compared with placebo and Yabukita recipients, those who had Sunrouge exhibited significant AA improvement after breaks (p=0.031 and p=0.048, respectively) and in between stress and break periods at week 8 (p=0.022 and p=0.006, respectively).
After stratifying for VDT use, Sunrouge recipients who operated VDTs daily also had significant AA improvement vs those who had Yabukita at week 8 (p=0.047).
Regarding eyestrain symptoms, top-heavy feeling was improved at week 12 with Sunrouge vs placebo among participants under 45 years (p=0.008). Among participants who operated VDTs daily, Sunrouge improved eyestrain at week 4 (p=0.047) and lower back pain at week 8 (p=0.027) vs placebo.
Long hours of VDT use increases eye stress and fatigue as well as sleep deprivation or mental stress which may consequently aggravate eyestrain, said the researchers. [Joho Shakai Gakkaishi 2006;1:64-72]
“[A]pproximately 90 percent of the Japanese population has eyestrain, making it one of the factors that [reduces] their quality of life,” said the researchers, adding that eye fatigue and strain are highly prevalent nowadays among younger individuals due to frequent VDT use.
The findings suggest that Sunrouge green tea might be beneficial for improving eye fatigue and strain, particularly among non-presbyopic individuals, they added.
The findings were also consistent with evidence showing improved eyestrain symptoms with blackcurrant anthocyanin, as well as improved objective contrast sensitivity in individuals with asthenopia and myopia following anthocyanoside oligomer administration. [Altern Med Rev 2000;5:553-562; Br J Nutr 2005;93:895-899]
Sunrouge is reported to have high amounts of the antioxidant anthocyanin, which is known to have eyestrain-reducing effects, as well as catechins – including the special methylated EGCG* – which are deemed effective for preventing lifestyle-related diseases. [Jpn Agric Res Q 2012;46:321-328; J Sci Food Agric 2012;92:2379-2386; Food Nutr Res 2017;61:1361779]
Despite the lack of serious adverse events associated with regular Sunrouge intake, the researchers cautioned against excessive Sunrouge intake due to the hepatotoxicity observed with excessive EGCG. [Green Light Weight Management, http://healthycanadians.gc.ca/recall-alert-rappel-avis/hc-sc/2006/9538r-eng.php?_ga=2.19965181.456035033.1523512048-1311801335.1523512048, accessed 15 May 2018).
Researchers recommended more randomized trials to further elucidate the impact of Sunrouge green tea on eyestrain reduction among non-presbyopic individuals with a workload that highly involves VDT use, as well as trials evaluating the right eye and before-rest conditions.