Hello.you should know that having untimely eating habits and eating spicy or oily foods can cause gastritis. Also drinking coffee and tea frequently also aggravates this condition.The most important thing is to follow a healthy diet which should include green leafy vegetables, fruits and berries which are rich in fibre.take fresh fruits instead of taking it in juice form, since the waste formed while making juice consist of fibres which will be beneficial for the gut, so prefer fresh raw fruits. Take lassi,yoghurt,buttermilk, ragi gunji instead of coffee and tea. Avoid smoked meat products. Avoid outside food, prefer only home cooked meal.drink plenty of water. And never skip a meal. Do daily morning brisk walking, yoga and meditation. If you are not satisfied consult a dietician.