Dear doctor;

Whenever I eat something that I have stayed away from for long, it upsets my stomach. Why would this happen? Is there something specific I need to do before jumping on a new food/ diet?

Nina, 21.

Dear Nina,

You have not specified in what way the stomach gets upset; is it always or sometimes? You may be having food allergies. Allergy can occur due to certain types of food which can manifest as diarrhea, bloating sensation, nausea or vomiting. There may be associated skin rashes, cold, etc. Proteins in the food, chemicals present as flavoring agents, preservatives, among others, can commonly cause allergy. 

Another problem can be dyspepsia or indigestion which occurs if there is constipation or one takes a starchy or fatty food or consumes alcohol. Try taking a nutritious diet including fresh green vegetables, fruits and whole grains, drink more water, avoid alcohol and the problem should improve.