Did not know that, but in my opinion, even if you don't drink coffee or red wine, you don't get a smile that bright without some kind of chemical whitening. And I'd go further to say he / his dentist overdid it, it is too white and too bright, which betrays the chemical nature (again that's just my opinion).
If he takes-up Suarez' Yerba mate-drinking habit his teeth will be back to a "natural" colour in no time.
Well I don't even know what Xylitol gum is but definitely isn't needed. It wasn't stated how long after a meal they wait before brushing their teeth but i think as long as you wait 30 minutes it's fine.
Not true my teeth are just as white and all I use is Colgate whitening toothpaste for an extra shine no chemical whitening or professional whitening needed. I mean nearly everything is composed of chemicals but you get my point ( I hope )