Does USAC Allow Natural Suppliments? I'm a non-competitive cyclist that wants to try a few Cat-5 USAC races for fun; unfortunately, at 40+ years of age, I'm taking more than one natural OTC supplement to self-medicate.  

Is there an easy way to tell which supplements are okay and which aren't?  

I looked at the WADA List, but that list looks a bit intimidating to me.  I also took the effort to email USAC [1] and USADA directly and they said in their own words that the supplements I take are probably okay; however, some such supplements often contain extra bonus substances that might cause a positive on an anti-doping test. 

[1] - Actually, USAC just told me to contact USADA.  USADA was the organization that actually "answered" my question.
I think you're looking at the lists backward - they have lists of banned substances.  Everything else is okay and permitted because its not banned.

So if your medication contains anything on the banned list you're best finding an alternative or dropping that product completely.

You're able to prove that you made inquiries, and that your supplements do not list anything on the banned lists.  You've done all you can short of getting your supplements chemically analysed, which is a bit extreme and unreasonable.

Imagine if you did get hauled up for having something in your test results - you have made more effort than most, and you have the paperwork/papertrail to prove it.

Just focus on your pre-race training, pre-ride the routes if at all possible, and plan your diet for before and during the event.  And plan on tapering nicely.