The context of the following conversation is Alex became infected with a virus.  There is no cure for virus diseases.:
Alex says I ended up becoming infected with the virus..
The friend responds Have you been taking your vitamins?.
Alex responds Yes, I always do. It's the best treatment since there is no pharmaceutical cure..
The friend responds Get lots of rest too..
Alex responds Definitely. I've also cut out all junk food and have been eating well..
The friend responds That's great and should help keep your immune system in top shape..