According to scientific studies conducted by Binghamton University it can truly be beneficial for some. In the study it indicates that 33% of participants experienced less stress and profoundly calm, just by changing their diet.
The food that they were eating were the one listed for the Mediterranean Diet .
Another interesting part of the study was that all the members of the families where there was at least one participant eating the different foods recorded their impressions of personal stress as well. If the participant believed they had less stress (and that was not disclosed to other family members) all family members reported less stress.
So eat good food and try not to stress out the rest of the family!