Probably an epidemiology study beings the professor was an epidemiologist. If so, it can establish correlation but not causation. Most of those studies have confounding circumstances like healthy user bias or other issues.

It was a meta analysis but if the analysis is of questionnaire studies it will be no better than the underlying data. Do you know how many cups of ribs you had in the last year? This is the kind of questions ask. Sometimes the questions are ask at the beginning of the study then no followup with the assumption that people have eaten the same way for many years.

Epidemiology is a good way to ask questions and get ideas of what controlled studies need to be done, but using them to make policy or decisions can lead to bad results.

John