Another food that should be avoided on a gastritis diet is coffee. Coffee contains both acid and caffeine. It may increase the rate of acid secretion in the stomach which could be the reason for irritation and discomfort in the stomach.
Use of coffee in gastritis can lead to the worse pain because when acid and caffeine come in contact with mucosa(stomach lining), it can cause inflammation and discomfort in your abdomen which may lead to bloating in the stomach. Consumption of coffee should be avoided if you are diagnosed with gastritis.
You may think that you can drink decaffeinated coffee, but it is highly acidic which may cause bad inflammation and worsen the pain. According to the Center of Science in Public Interest decaffeinated coffee contains a minimum amount of caffeine and as much acid as in a regular coffee. A cup of decaffeinated coffee contains 3-11 grams of caffeine. Whether caffeinated or not, coffee should be avoided in such a case.