ADD isn't really something you "cure", more something you learn to live with.  I've been diagnosed with ADHD since I was 11yo.  What has helped me more than anything was going vegan, eating whole foods, and sticking to a regular workout routine.  Avoiding sugar also helps, but I've never been able to do that for very long :)

If you've made it this far, you should totally avoid medication because you've learned to cope without it.  My Dad was diagnosed when he was around 45 years old, and the medication only bothered him.  I was medicated until I was in my 20s, and I've spent the last ten years learning to live without meds.  I'm still a little flakey sometimes,  but I've found keeping a regular schedule and forcing myself to plan ahead has really helped.

Good luck!

I've read that staying away from artifical colors/flavors/heavily processed foods helps. 

http://www.webmd.com/add-adhd/guide/adhd-diets

Yea I agree with the poster who said there's no "cure", just learning/deciding to live in a way that works for you. I'm ADD, wasn't diagnosed til 16 and refused medication, which my doctor was fine with because he said I'd lived with it long enough that I had my own strategies in place already without realising it.

I definitely find that eating a good diet (doesn't have to be perfect, but mainly decent) of lots of fresh and whole foods, less processed stuff helps. Avoiding caffeine on the whole helps too, it doesn't do nice things to te ADD body chemistry. The biggest thing for me is exercise, I need a lot of it, and when I'm getting enough my entire state of being is calmer and happier.

I mainly just try a live in a way that keeps me active and interested - I could never do a 9-5 office job, and I recognise that, so I do work with a lot of variety and movement. I know that I can't sit still and quietly to "concentrate" so I study with music and in short intense bursts. I draw pictures when I have to sit and listen because it keeps the spazzy part of my brain busy so I can focus. It really is about what works for you. A few weeks ago I had to sit in one room listening to lecture for 8 hours, and didn't cope with it well at all, it was horrible...but it was great, because it made me realise that I rarely feel like that anymore. Which means I am doing fine just by knowing myself and how I best operate.

I reckon ADD is kinda awesome :) You don't get a chance to be boring, and the itense bursts of creativity and productivity are really fun and satsfying.