Hi there,
I've made some tests regarding this problem and i think it's not random. I tried to check my invotory at every moment on the first mission.
The food and meds did not disappear when hit or die but at some points in the mission.
Ffirst it was in the office where you deactivate the vox but i didnt take screens. But at another point when you talk to the guy in the outpost before the bridge.
After talking to him and kill the robots i still got my foods in my inventory
Each time i pass the outpost to continue my food and meds disapear
and hopefully the autosave was at this moment and if i load back the save they are still here and i've repetead the process multiple times just to be sure it's not just a coincidence.
I hope it help.