Abstract
Purpose :
Dark chocolate (DC) from flavanol-rich cacao beans improves cardiovascular function, reduces symptoms in Alzheimer and Parkinson disease, and improves vision. Our purpose was to compare effects of a DC bar to a white chocolate (WC) bar (no flavanol content) on multi-focal electroretinograms (mfERGs) which assess retinal function from multiple sites.
Methods :
26 visually normal adult subjects (mean age ± SD = 27 years ± 3, 17 females, 9 males) participated in a randomized, double-blind crossover study to assess mfERG amplitude and latency after consumption of a DC or a WC bar comparable in all ingredients except for flavanol content (total flavanols DC: 316.3 mg, WC: 0 mg). The Diopsys® mfERG stimulus consists of 19 hexagons pseudo-randomly reversed (white 204 cd/m2, black <0.5 cd/m2) for four 1 min. periods. Mean responses were recorded from the central 5 deg. (R1: fovea), R2 (5 to 22 deg.) and R3 (22 to 42 deg.). Each subject was tested 45 minutes after consumption of the DC or WC bar in separate, counter-balanced sessions separated by at least 72 hours. Double-blinding was assured by having subjects consume each bar wearing eye patches and experimenters were unaware of the chocolate type.
Results :
Two-way analysis of variance across mfERGs and chocolate type (DC vs. WC) showed no difference between DC and WC for N1-P1 amplitude (F=.03, p>0.8) or P1-N2 amplitude (F=1.1, p>0.2). However, P1 latency was significantly shorter for DC vs. WC (F=7.3, p<0.01). DC foveal latency was 39 msec. vs. 42 msec. for WC (p<0.02). Summation of all latencies were significantly shorter for DC (112 msec.) vs. WC (117 msec., p<0.02). Throughput, which combines amplitude and latency and is calculated as the ratio of P1-N2 amplitude/latency showed a significant increase for DC vs. WC (p=0.05). P1-N2 amplitude is related to optic nerve function consistent with our recent evidence for decreased VEP latencies after DC.
Conclusions :
Acute consumption of a DC bar decreased mfERG latency and increased throughput consistent with faster processing revealed by shorter VEP latency and in agreement with improved contrast sensitivity (Rabin et al.). Small DC visual enhancements in healthy individuals may underestimate potential improvements in elderly and/or diseased patients who may benefit more from improved blood flow and/or antioxidant effects of cacao rich flavanols in DC.
Rabin et al. JAMA Ophthalmol. 2018;136(6):678–681.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.