A lot of people fall victim of brushing their teeth after meals so as to keep their teeth sparkling. Don’t brush your teeth immediately after meals and drinks, especially if they were acidic. Acidic foods—citrus fruits, sports drinks, tomatoes, soda (both diet and regular)—can soften tooth enamel “like wet sandstone,” says Howard R. Gamble, immediate past president of the Academy of General Dentistry. Brushing your teeth at this stage can speed up acid’s effect on your enamel and erode the layer underneath. Gamble suggests waiting 30 to 60 minutes before brushing.