Credible:
1.Ina Ilse's comment seems to be expressing neither fear nor hope for the situation, instead, they take a completely neutral stance by explicitly weighing out both sides of the argument.
2.This commenter appears to be pro-Vitamin D, and believes that Vitamin D can support an individual if they don't already get enough of the vitamin from the sun. These beliefs are concluded by Ina's use of mentioning the supplements as possibly having a "[positive] effect".
3a. This comment seems credible to me because it is calm and collected, while also mentioning background knowledge about the sun exposure in place of supplements, adding to making this comment seem knowledgeable and reliable.
1. Dr. Gerard Schnuerer's comment seems to be in fear of the situation, believing there is bad data/ a bad metaanalysis. It is clear through the diction and tone of this comment (referring to the topic as "urgent"), that the commenter is not happy with the situation.
2. Dr, Schunuerer seems to be pro-Vitamin D, and con-the presentation of "facts" against Vitamin D. This stance is seen through Dr. Schunuerer mentioning good things about the vitamin, such as it being "almost impossible to overdose" on.
3a. This comment seems credible to me because of its length, its formal and factual diction (medical terms), and even just the commenter's name. Coming from a doctor who seems to know much about vitamins and medicine, I trust that this commenter's information is factual and that they are a reliable source. They also kept themselves relatively composed which helps add to their credibility.
Not Credible:
1. This comment seems to fear the situation. Not only do they seem angry and frustrated with the situation now, but they claim to have been afraid of it for 5 years!
2. Dr. todd forman seems to be anti-Vitamin D, because of their request to stop the "need to prescribe for everything and anything", but it is not entirely clear since the comment is so short and poorly worded.
3b. This commenter seems to lack credibility because of the shortness of their comment, the poor grammar/structure of the comment, and the heated anger coming from this comment, which makes the commenter too attached to have a credible opinion.
1. wang bing seems to have hope for the situation, and appears to think there is much more research to be done on the topic.
2. This commenter appears to have no stance, but simply says that the "information" provided is great, which hints that they are pro-Vitamin D.
3b. This commenter does not seem credible because of how short their comment is. There is nothing a reader can gain from this comment, as it does not provide any evidence, new information, or stance on the issue, so there is nothing to be credible of this comment.