Best/worst gluten and dairy substitutes?

[Owlie]

pardon me for hijacking the thread somewhat, but I've been thinking about this recently and wanted to ask:

how would you know that you are gluten intolerant or gluten sensitive, and are there health benefits to eating less gluten (and dairy for that matter) if you're not gluten intolerant?

I ask because I'm generally interested in healthy eating and try to keep an open mind to trying new stuff, my dh is dairy intolerant and I've grown increasingly so myself because of low exposure, and I just recently met several people at work who said that they could eat gluten but preferred not to because they "felt better without".

Thanks for asking this, as I've been wanting to know myself.