Abstract
Background: Energy drinks have gained popularity amongst young adults in recent years. Widespread effects of its main ingredient caffeine have been observed on the nervous system; however, little is known about the effects of these drinks on the visual system.Aim: This research study investigated the effects of a chosen energy drink on near vision and near contrast sensitivity.Setting: The data were collected at a university optometry clinic in south eastern South Africa.Methods: A single-blinded, crossover study was conducted on 56 healthy subjects aged 18–30 years. Subjects were randomised, such that they consumed either the energy drink reboost or water (control) on separate days. Near visual acuity was measured using a near Logarithm of the Minimum Angle of Resolution (LogMAR) chart and contrast sensitivity using the MARS contrast sensitivity test. Near visual acuity and contrast sensitivity measurements were taken at baseline and again at 30 min, 60 min and 90 min intervals, following consumption. Data were analysed using repeated measures analysis of variance (ANOVA) and univariate analysis.Results: Both near visual acuity and contrast sensitivity, post-energy drink consumption, showed a marginal increase over the testing period. Near visual acuity increased from –0.13 LogMAR at baseline to –0.17 LogMAR at 90 min. Contrast sensitivity increased from 1.77 log units at 30 min to 1.78 log units at 90 min similar to that observed with the control. In both cases; however, the changes were neither statistically (p 0.05) nor clinically significant.Conclusion: The energy drink reboost had no short-term effect on near vision performance as measured with near visual acuity and contrast sensitivity.
Highlights
By 2006, there were more than 500 varieties creating a multibillion dollar industry for manufacturers and distributors,[3] with South Africa showing the third highest increase in sales for the years 2013–2014.4 Energy drinks were initially marketed to athletes as ‘energy boosters’; the focus of marketing strategies has more recently shifted to adolescents and young adults, the majority of whom are males aged 13–35 years.[5]
A total of 56 healthy subjects (36 females and 20 males), with a mean age of 20.52 ± 2.30 years and mean body mass index (BMI) of 23.71 kg/m2 ± 4.80 kg/ m2 participated in this study
It was considered of particular http://www.avehjournal.org importance to assess the effect of energy drinks on near visual performance, which could influence their learning as students often consume energy drinks, during study and examination periods
Summary
Energy drinks have become increasingly popular over the years with the global sales having reached 57.4 billion dollars in the year 2020.1 Even though the first energy drink was introduced in 1949, they only became popular in 1997 with the introduction of Red Bull.[2,3] By 2006, there were more than 500 varieties creating a multibillion dollar industry for manufacturers and distributors,[3] with South Africa showing the third highest increase in sales for the years 2013–2014.4 Energy drinks were initially marketed to athletes as ‘energy boosters’; the focus of marketing strategies has more recently shifted to adolescents and young adults, the majority of whom are males aged 13–35 years.[5]. On a weekly basis, has been found to be associated with the male gender, smoking, alcohol consumption and being overweight.[6,7] These beverages contain caffeine in combination with small amounts of taurine, B vitamins, guarana, ginseng, sucrose, glucuronolactone and inositol.[8]. Glade,[10] following a detailed literature review of the beneficial effects of caffeine on human physiological systems, reported that caffeine decreases fatigue, enhances physical and cognitive performance, increases alertness, decreases mental fatigue and enhances short-term memory. These may be some reasons for its popularity with young adults and anecdotally more at stressful times such as during examinations. Widespread effects of its main ingredient caffeine have been observed on the nervous system; little is known about the effects of these drinks on the visual system
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