Updating on my Google Nexus 5.0.1

Hi! I have been using Google nexus 5.0.1 before and it was a great experience. Everything worked fine. Now I am manually updating it to 5.1 but I don't know if its without a risk? I mean is there any chance that I might lose all my data during this update because I cannot afford to lose my data at any cost. Please reply asap. Thanks!
