Institutional offices for the communication and dissemination of science are gaining importance at Spanish universities, and their activities can contribute to increasing the visibility and reputation of researchers. This study aims to analyze the relations between the institutional communication of research results to the public and the impact and academic visibility of scientific papers. For this purpose, science communication and dissemination through press releases on R+D+i results from the Science Culture and Innovation Unit (SCIU) at Universidad Carlos III de Madrid (UC3M) were selected as a case study. This SCIU was chosen because it has published yearly reports for more than a decade on the impact in the media of its press releases. Press dossiers of the last five years available (2014-2018) were examined. A database was created of the citations received by texts published in scientific journals indexed in the Web of Science and their mentions on social networks through the company Altmetric.com. After that, this information was statistically analyzed. The main results show that the journal impact index is important for obtaining academic citations or appearing in Twitter conversations. However, the influence of the journal impact factor turns out to be lower when it comes to popularizing scientific publications in the media. Furthermore, the statistical evidence points out that scientific publications disseminated through the SCIU receive proportionally more citations than research that has not been disseminated through the institutional channel.