Some children become quite interested in designing their own hypotheses to see whether certain actions or foods have an effect on staying dry overnight. Working to identify their own personal bed-wetting triggers can be beneficial for kids on two fronts:
It gives them a sense of control over their bed-wetting problem and allows them to take some responsibility for trying to fix it.
If they do identify a food they think prevents or causes bed-wetting, having or avoiding that food may actually help, even if it is only due to the placebo effect.