Greetings!
I think that, in order to start the introduction, you will need to know which direction your paper will go in. For example, if your preliminary research indicates that the nutrition training for medical students is inadequate, your introductory paragraph will indicate that. Your thesis will take a position such as "Although there has been improvement in recent years, the emphasis medical universities give to the study of nutrition remains inadequate."
You will want to find articles in professional nutrition journals, such as the American Journal of Clinical Nutrition and Nutrition Journal. You might also want to search medical journals such as the Journal of the American Medical Association. Finally, you could also look at the curriculum for medical students at some major medical universities to see just how many courses in nutrition they require/offer.
I hope this helps get you started!
Thanks,
Sarah, EssayForum.com
Sarah, EssayForum.com