There is not a particular type of food that helps reduce anxiety, but maintaining an overall healthy diet is absolutely primordial.
Staying away from alcohol and caffeine has been shown to help reduce anxiety symptoms. Similarly, eating more fruits and avoiding foods with high sodium content like fast foods and processed foods (e.g., chips) have also been associated with reduced anxiety.
Vitamin B6 and B12 have been investigated and they were found to have anxiolytic effects (i.e., reduce anxiety) as well.