Oral consumption of Garcinia kola(Bitter kola) lowers intraocular pressure

Garcinia kola (bitter kola) is locally ingested across the West African subregion. It has ocular hypotensive effects similar to some commonly used glaucoma medications when administered topically. The study assessed the effect of oral ingestion of G. kola on intraocular pressure (IOP).

A randomized, single-blind, placebo-controlled, cross-over design was used in this study. Forty-six healthy subjects, aged between 19 and 27 years were recruited and randomized into two groups (A and B). Subjects in group A ingested 100 mg/kg body weight bitter kola in a 200 ml solution on their first visit and group B ingested 200 ml of water. On the second visit, the order of treatment was reversed, IOP was measured at baseline and every 45 min interval for 135 min. The mean difference between the baseline and post-treatment IOP measurements were tested for statistical significance using repeated-measures analysis of variance (95% confidence intervals [CIs]).

Mean IOP measurements decreased by 7.9, 18.2 and 20.6% at 45, 90 and 135 min, respectively, after G. kola treatment. The reduction, though variable across subjects, was statistically significant (F [2.13, 95.62] = 90.35, p < 0.0001) across the respective time points. Repetition of an identical protocol without G. kola caused clinically negligible changes in IOP. There was no statistically significant influence of gender or age in G. kola effect on IOP reading.

Oral ingestion of G. kola lowered the intraocular pressure of healthy young adults by 21%. Such an effect may be of therapeutic benefit to patients with POAG or ocular hypertension in low-income settings.