The information provided can support the prediction that the essay contains up-to-date information based on the following:
1. **Publication Date**: The fact that the essay is set to be published in the September 2015 issue of the magazine indicates that it is relatively recent. This suggests that the content is likely to be current and reflect the latest developments and perspectives on veganism.
2. **Title**: The title of the essay, "A Defense of Veganism," suggests that it will present arguments in support of veganism. Given that the topic of veganism continues to evolve with new research, trends, and discussions, a defense of veganism published in 2015 would be expected to include contemporary viewpoints and information.
Considering the publication date and the nature of the topic, it is reasonable to infer that the essay is likely to contain up-to-date information supporting the prediction.