Generally, it is fine to brush your teeth before eating! It might make orange juice taste bad after but according to the EAPD, brushing before breakfast will “remove the build-up of plaque thereby minimizing the acidogenic response of the oral bacteria present of the foods eaten.” If you really cannot stand the the taste of toothpaste before eating, you can brush without toothpaste since water and bristles can still be quite effective. (x)
But what of brushing right after? Surprising to some, brushing too soon after a meal can lead to further tooth abrasion. The pH in your mouth has been dropped after a meal and needs time for the saliva to neutralize the mouth. The ideal intra-oral pH is supposedly 7, while foods can drop it below 5.5. The pH 5.5 is the point when teeth demineralize. How long must you wait for neutralization? This colgate article suggests 30 minutes while another colgate article suggests 60 minutes. The EAPD article stated 20-60 minutes, so I suppose 60 minutes is the safer wait, although 30 minutes is the more common wait.
In the meantime, the Online Wall Street Journal suggests you can rinse your mouth with water while you wait. Rinsing straight after consuming acidic drinks is still recommended. Chewing string cheese will also reduce the pH. (The wine and cheese combo makes more sense now, yeah?) Chewing sugar-free gum also wouldn’t hurt since the xylitol content will help you remineralize your teeth.