Hi Lane,
I think it would be perhaps be good to differentiate as 'the source' and 'a source'. I sincerely hope that people around the world only use Wikipedia as *a* source for health information. The current wording is a bit fuzzy about this. We can probably confirm that it is popular as a source, but we don't know for sure if that is to get an initial idea what words mean, as some kind of elaborate dictionary, for background information, for access to the reference section etc.
Also, the last sentence assumes that the online sources are the biggest chunk of sources for medical information. Maybe it's a lame argument, but I'd suggest that the doctor (general practisioner) or even family is still the single most popular source for health information in the world. The word 'source' is a bit too vague to use in this context. Maybe resource or compendium makes more sense?
Best, Lodewijk
+1 to this line of clarification