Twenty-nine percent use the Internet for medical information, and 70 percent of that group look on the Net before visiting a doctor. Bernstein said people most often search for information on cancer and heart disease. Many join online support groups. But much on the Internet can be deceptive. The CSPI said it has received reports of companies advertising dietary supplements on the Internet even though they have been removed from the market by the Food and Drug Administration.
Some companies post seemingly scientific, but often unsubstantiated research on their products.
The Associated Press contributed to this report.