Looking at it now I think I probably needed to be clearer and give better feedback in game on how to interact with the different items.
Eating - Interact by starting to eat, then you have to wait until eating is complete for it to take effect.
Shield - Interact and the value increases as you continually repair by not leaving the repair point.
Life Support - Interact when damaged, repair will take a set amount of time and when repaired it is fully repaired.
Engine - Interact and the value increases as you continually repair by not leaving the repair point.
Thank you for playing. I appreciate the feedback.