Boyfriend's Health

So, my boyfriend has Aspergers, which means that he is on the Autism spectrum. He doesn't seem to have an issue being social or really have any of the signs of actually having Aspergers, except being a picky eater. He refuses to eat vegetables. I tried reading up on Aspergers and issues with foods, and all I found was that most children out grow being picky by around age 8, with the help of parents encouraging then to eat well of course. However, I don't think his parents did that. I think they just let him eat and not eat whatever he wanted so they wouldn't have to deal with it. We have been together for almost 4 years now and he won't even have a discussion about changing his diet. He just gets angry. I'm at the point where I would like to marry him and at some point have kids, but I don't want to be with someone who refuses to eat healthy for the sake of our children in the future and his own health because he is more prone to heart problems from his family. I don't want to sound insensitive to his disability, but it just feels like an excuse when he won't try new things and gags when he sees vegetables. I just don't know what to do, and if any of you guys have any advice on how to get him to be more open to being healthy and trying new things, I would deeply appreciate it.