Illness and poor diet

I have a teen son who has never liked or really eaten his veggies or fruits, he would hide them or spit them out and constantly gags until he throws up.  I have given him vitamins and purchased the fruit drinks that have veggies in them to help with his diet but do not think this is helping.  Recently in the last year he has seemed to catch every cold, flu and what have you.  I am concerned about this and figure that it is connected to his poor diet.  Therefore, I am trying to find ways to get him to eat the good stuff that he says he can't and won't eat.  Telling him he can go without doesn't help, as he just waits until the next day and sees what there is and if it is something he doesn't like he just goes to his friend's house and has something.  I am open to any ideas that might help.  Thanks

[Paxiled]

Spirulina or wheat grass tabs would provide a much better vegetable source than oxidized veggies in a prepared fruit drink.  If he'll take pills.  They don't taste like anything, but you have to take a lot of them at a time to get enough that way.  He is a teen, they do get sick a lot anyway, and he will grow out of it.  Tough love is the other way, but if he goes to the extreme of gagging I don't know how you'd do that.  Sounds like a very determined rebel there.  You might also take him to a good health food store and show him about organically grown veggies.  First, they taste a whole lot better.  Second, maybe you can appeal to the rebel in him by explaining the organic movement.  Just a thought.  I used to manage health food stores, and a lot of organic fanatics were young folks very delighted to be different.