Yes. The acid in the food can harm the enamel and brushing it to soon can remove it. So wait at least 30 minutes, brush before or avoid acidy foods.
Brushing abrasion of softened and remineralised dentin: an in situ study
T Attin et al. Caries Res. Jan-Feb 2004 [Source]:
It is concluded that for protection of dentin surfaces at least 30 min should elapse before toothbrushing after an erosive attack.
If you've eaten an acidic food or drink, avoid brushing your teeth for
at least 30 minutes. These acids weaken tooth enamel, and brushing too
soon can remove enamel. If you know you're going to eat or drink
something acidic, brush your teeth beforehand.
Acidy foods: oranges, lemons, and grapefruit
Drinking water after you eat the acidy foods helps easy it away
Also, brushing before eating can remove a lot of bacterial buildup, before you start eating again.