Virginia Tech's University Libraries gives you access to nearly 1,000 databases. How do you know where to start?
If you like, check out the HNFE Subject Guide, a webpage that will point you to the best databases for Human Nutrition, Food, & Exercise research at VT.
For introductory research, I recommend: PubMed, CINAHL, or Web of Science. If your question is agriculture-related, I would also suggest CAB Direct.