Here is an example of a secondary ("popular") source reporting on a research study.

According to this article, I would recommend coffee drinking to my elderly mother who is having heart problems.

If I were skeptical, I would find the original article (primary source) to review the research. Here are a few quotes from the Discussion section of the original article:

"Our results do not allow us to conclude whether caffeine or the caffeinated beverages were responsible for the protective effect...." "Overall, our findings do not allow for a conclusion as to whether caffeine ingestion protects against heart disease mortality by inducing blood pressure increases that counteract postprandial hypotension..." "The current study has several limitations...." "This study does not provide a valid basis for recommending increased consumption of caffeinated beverage...." (Greenberg, J. A., Dunbar, C. C., Schnoll, R., Kokolis, R., Kokolis, S., & Kassotis, J. (2007). Caffeinated beverage intake and the risk of heart disease mortality in the elderly: a prospective analysis. Am J Clin Nutr, 85(2), 392-398.)

If you were writing a scholarly paper about the effects of caffeine on the heart, would you cite the MSN article or the primary source?