Abstract
Purpose:
The main active ingredients in various energy drinks like Red Bull are caffeine and taurine. The caffeine, a psychostimulant (methylxanthine derivative) is known to increase the intraocular pressure (IOP), on patients with normal tension glaucoma, by approximately of 2 mm Hg over a period of two hours, while the taurine, an amino acid naturally synthesized by the human body, is known to reduce the intraocular pressure (IOP). The present study proposes to investigate the influence of the energy drinks (Red Bull) on the blood oxygenation of the optic nerve’s capillaries, in healthy subjects.
Methods:
Fifteen healthy university students, non-smokers subjects, aged of 20-27 years (23 years ± 3) have participated to this study. The blood volume and oxygenation (BVO) of the optic nerve’s capillaries have been assessed using a multichannel spectroscopy technique (Diaconu 2010). A preliminary BVO measurement has been considered as a baseline for each subject. The subsequent 5 measurements were obtained at 15 minutes of interval for the next hour, after the subject drank a quantity of 250 ml of water or of Red Bull. The subjects participated in two experimental sessions of a minimum of two weeks of interval. In one experimental session, the subject drank 250 ml of water and in the subsequent experimental session, the subject drank 250 ml of Red Bull. The intraocular pressure (iCare tonometer), the brachial blood pressure (automatic sphygmomanometer), the heart rate (automatic sphygmomanometer) and the systemic arterial blood oxygenation (pulse oxymeter) have also been measured in each subject during the experimental session.
Results:
The results show that, the Red Bull drink induces a vasoconstrictor effect on the optic nerve capillary structures in each participating subject. About 15 minutes after ingesting Red Bull, the blood oxygenation in the capillaries’ has decreased, an average of 7,8%, and has continued to remain low 60 minutes later. Drinking water had the effect of increasing the blood oxygenation in the optic nerve capillary structures and has achieved a significant increase of 8%, about 45 minutes later.
Conclusions:
Red Bull should not be a recommendable drink for patients with a weak blood flow in the capillaries’ structures of the eye, like various types of glaucoma. However, water remains beneficial drinking for these patients.
Keywords: 629 optic nerve •
635 oxygen •
548 hypoxia