a month long break from cycling...

What are your injuries?

Taking time off from an injury is necessary if the doctor says to take time off, obviously he/she wants your body to heal and do so without aggravation of the injury.  In that light your going to loose some of your physical stamina, no way around it.  You may want to ask your doctor about any excersing you can do to either prevent that or slow it down, and he/she can guide you in a direction that won't effect the injury.  But always check with the doctor, don't take some public forum advice or your own thoughts to skirt around that or could hurt yourself worse and be faced with even a longer time off the training program.

Food wise, try this, not sure if it really works but it can't hurt you that's for sure.  http://livelighter.org/heal-faster-with-these-foods/

http://shannonclark.hubpages.com/hub/Foods_To_Heal_An_Injury

http://www.coreperformance.com/knowledge/nutrition/healing-food.html

I don't usually buy into all the vitamin crap because if you eat right you take in all the vitamins you need in the most natural way in which the body was to take it, thus nothing is wasted.  But when you take a vitamin pill the body rejects about 93% of it, that's why when you urinate the pee is a bright yellow...your peeing the vitamins you spent big money on down the toilet.  Also overloading the body with vitamins can actually do more harm then good by increasing toxic levels of the vitamin your body was not suppose to have resulting in some major problems from cancer formation to liver disease and other ailments.  If you feel so inclined to take a vitamin then buy the cheapest one a day you can find, because whether it's cheap synthetic or expensive natural stuff your body will reject at least 93% of it; and there's been no proof natural is better then synthetic; also with the cheap one a day variety your not going to be overdosing on mega amounts of vitamins.