I think the typical vitamin articles you will find from Dr. Nick online are not acceptable sources, or at least wouldn't have been where I went to college. Your college should enable you to have access to academic search engines like EBSCO, or LexisNexis. If you are in high school, then just go to the library, but your teacher probably won't give a shit about good sources in high school anyway. Also, remember to take your
vitamins before writing the article.