According to a study of how people evaluate and act on online health advice, information written by a doctor is considered more credible when it appears on a Web site than on a blog or a homepage. The findings, published in the Journal Communication Research, highlight the relative importance of different online sources to people who seek health information on the Internet.

"Most people look for health information online by keying disease symptoms into various search engines," said S. Shyam Sundar, distinguished professor of communications, Penn State. "But the results of that search could range from experts at the Mayo Clinic to somebody's personal blog."

Researchers found that study participants were more likely to believe -- and make use of -- information on a website from a source identified as an expert than from a layperson. Health information from the websites of TV, radio, and newspapers was not included in the study.

Participants also believed that editors and moderators help websites present accurate and complete information. Blogs, homepages, and social networking sites were seen as lacking such gatekeeping.

555 college students were presented with screenshots of one of two health articles, attributed either to a doctor or to a layperson. Students received these articles as either from a formal website, individual homepage, a blog, a bulletin board -- a chat site where people can post messages -- or were simply told that they came from the Internet.

The first article discouraged the use of sunscreen to avoid Vitamin D deficiency, while the second advocated the consumption of raw milk over pasteurized milk. "We wanted to find out if users differentiate between various sources of online information and how that choice impacts their decisions," said Sundar. "The health topics were controversial enough to raise questions of credibility among readers."

Statistical analyses of student questionnaires suggest that screenshots of both health topics were seen as significantly more reliable when attributed to a doctor and featured on a website rather than on a blog, individual homepage or a bulletin board.

"It tells us that young people are actually differentiating between different online sources when evaluating health information on the Internet," said Sundar.

Students were also significantly more likely to follow up on the advice they had received through websites and bulletin boards -- compared to blogs and homepages -- by acting on it and sharing it with friends.

"It is the future of how health information will be distributed over the Internet," said Sundar. "If doctors are serious about disseminating health information, they should do it on a bulletin board instead of a homepage."

Citation: Yifeng Hu, S. Shyam Sundar, 'Effects of Online Health Sources on Credibility and Behavioral Intentions', Communication Research, February 2010, 37(1), 105-132; doi: 10.1177/0093650209351512