Not to put a damper on your upcoming Halloween parties, but the highly publicized ocular health benefits of dark chocolate touted last year might not be as sweet as originally advertised. Neither 20g of flavanol-rich dark chocolate, nor 7.5g of milk chocolate had any short-term effects on either retinal blood flow or subjective visual function, according to a buzz-killing team of German researchers.1

The study, published in JAMA Ophthalmology, was in response to an April 2018 article in the same journal linking improved small-letter contrast sensitivity to dark chocolate consumption. The 2018 study also suggested the potential for flavanols—a group of compounds thought to be behind the benefits—to increase blood flow.2

The more current research evaluated 22 participants and saw no relevant differences in baseline parameters, and no change in retinal perfusion, no differences in visual acuity, Pelli-Robson chart, or Mars chart contrast sensitivity after chocolate consumption. The joyless study used OCT angiography to image retinal perfusion.1

“The small trial does not rule out the possibility of benefits,” the investigators concluded, leaving chocoholics hoping to justify their cravings as a preventative health measure a sliver of hope.

1. Siedlecki J, Mohr N, Luft N, et al. Effects of flavanol-rich dark chocolate on visual function and retinal perfusion measured with optical coherence tomography angiography: A randomized clinical trial. JAMA Ophthalmol. September 26, 2019. [Epub ahead of print].
2. Rabin JC, Karunathilake N, Patrizi K. Effects of milk vs dark chocolate consumption on visual acuity and contrast sensitivity within 2 hours. JAMA Ophthalmol. April 26, 2018. [Epub ahead of print].